You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Export thread
16.5 single cylinder popping and missing greatly
#1
M
mr.farmall
M
mr.farmall
16.5 hp single cylinder vertical OHV 3100 series Briggs & stratton on a Husqvarna zero turn mower. 31E877 1502-G1
The engine is burning a lot of oil, about 1/4 cup every 2 hours. No oil leaks. The plug is continually fouled, and is cleaned often. It has run ok in the past, but now it is starting to miss-fire and it has to be hard on the engine and fly wheel, with a big 3 inch piston and having a large and heavy flywheel When it miss-fires and then pops it creates quite a strain on the whole system, sounds like it is going to break the flywheel loose. (it does require a steel key in the flywheel.)
I have checked the flywheel key and the timing, it looks good. The carburetor has been cleaned. The fuel pump is working and the fuel shut off solenoid is work correctly.
The compression is about 90 psi. I got a leak down tester and it shows 40% leakage on the gauge. I hear no air noises in the carburetor intake nor the exhaust, but I do hear a substantial air hissing through the oil filler hole.
The engine has been serviced a lot. This engine runs fine for a while then begins to running poorly and has needed work since the beginning, more work than all of the other equipment all put together. It's only 4 years old. I'm very disappointed with it.
What I could use your advice and expertise with is the following;
1. Should this engine just be replaced with something like a twin cylinder about the same size?
2. What kind of problems would that create, mounting, electrical, fuel, etc.?
3. Should I try to replace the ring set? If the cylinder walls look good.
4. Could the miss-fire be from one of the safety switches, like the seat, going bad? and if so , how would you test for it?
Thanks for any help.
The engine is burning a lot of oil, about 1/4 cup every 2 hours. No oil leaks. The plug is continually fouled, and is cleaned often. It has run ok in the past, but now it is starting to miss-fire and it has to be hard on the engine and fly wheel, with a big 3 inch piston and having a large and heavy flywheel When it miss-fires and then pops it creates quite a strain on the whole system, sounds like it is going to break the flywheel loose. (it does require a steel key in the flywheel.)
I have checked the flywheel key and the timing, it looks good. The carburetor has been cleaned. The fuel pump is working and the fuel shut off solenoid is work correctly.
The compression is about 90 psi. I got a leak down tester and it shows 40% leakage on the gauge. I hear no air noises in the carburetor intake nor the exhaust, but I do hear a substantial air hissing through the oil filler hole.
The engine has been serviced a lot. This engine runs fine for a while then begins to running poorly and has needed work since the beginning, more work than all of the other equipment all put together. It's only 4 years old. I'm very disappointed with it.
What I could use your advice and expertise with is the following;
1. Should this engine just be replaced with something like a twin cylinder about the same size?
2. What kind of problems would that create, mounting, electrical, fuel, etc.?
3. Should I try to replace the ring set? If the cylinder walls look good.
4. Could the miss-fire be from one of the safety switches, like the seat, going bad? and if so , how would you test for it?
Thanks for any help.
#2
I
ILENGINE
I
ILENGINE
Ten to one says you have a blown head gasket. Pull the head and take a look. Will be blown between the cylinder wall and the push rod cavity.
#3
B
bertsmobile1
Answers to your questions
1) Can be done , get better power delivery not cheap not easy, bigger single will be easier.
2) bolt holes have the same centres , you can swap over your old alternators so no connection problems other than lengthening the wires, Custom control wires are easy to do custom exhausts are not so easy
3) always try the easist / cheapest first and check things before you jump in. Every day people come to this list having spent $ 300 + on new parts when all that was needed was an adjustment.
So ask first , check second & buy last, Pull down on Sunday so you can get your replies Monday get parts Wednesday and have yourself back on te grass by the weekend.
I will go with Ilengine as blown head gaskets ar a big problem on this model and about 1/2 day amateur fix once parts are in hand. Replacing rings will blow it out to a 2 day job and introduce a lot more chances of creating problems that you did not have in the first place.
4) not usually a safety switch generally just kills the engine stone dead. You check by undoing the cut out wire on the coil which removes all of the controls INCLUNING SHUTTING DOWN THE ENGINE ( get the hint ).
An oil fouled plug will cause a miss , popping and even an engine destroying backfire through the carb.
5) Do not ever even think about replacing the alloy shear key in the flywheel with a power transmission steel key no, no , no, never ever.
B
bertsmobile1
16.5 hp single cylinder vertical OHV 3100 series Briggs & stratton on a Husqvarna zero turn mower. 31E877 1502-G1
The engine is burning a lot of oil, about 1/4 cup every 2 hours. No oil leaks. The plug is continually fouled, and is cleaned often. It has run ok in the past, but now it is starting to miss-fire and it has to be hard on the engine and fly wheel, with a big 3 inch piston and having a large and heavy flywheel When it miss-fires and then pops it creates quite a strain on the whole system, sounds like it is going to break the flywheel loose. (it does require a steel key in the flywheel.)
I have checked the flywheel key and the timing, it looks good. The carburetor has been cleaned. The fuel pump is working and the fuel shut off solenoid is work correctly.
The compression is about 90 psi. I got a leak down tester and it shows 40% leakage on the gauge. I hear no air noises in the carburetor intake nor the exhaust, but I do hear a substantial air hissing through the oil filler hole.
The engine has been serviced a lot. This engine runs fine for a while then begins to running poorly and has needed work since the beginning, more work than all of the other equipment all put together. It's only 4 years old. I'm very disappointed with it.
What I could use your advice and expertise with is the following;
1. Should this engine just be replaced with something like a twin cylinder about the same size?
2. What kind of problems would that create, mounting, electrical, fuel, etc.?
3. Should I try to replace the ring set? If the cylinder walls look good.
4. Could the miss-fire be from one of the safety switches, like the seat, going bad? and if so , how would you test for it?
Thanks for any help.
Answers to your questions
1) Can be done , get better power delivery not cheap not easy, bigger single will be easier.
2) bolt holes have the same centres , you can swap over your old alternators so no connection problems other than lengthening the wires, Custom control wires are easy to do custom exhausts are not so easy
3) always try the easist / cheapest first and check things before you jump in. Every day people come to this list having spent $ 300 + on new parts when all that was needed was an adjustment.
So ask first , check second & buy last, Pull down on Sunday so you can get your replies Monday get parts Wednesday and have yourself back on te grass by the weekend.
I will go with Ilengine as blown head gaskets ar a big problem on this model and about 1/2 day amateur fix once parts are in hand. Replacing rings will blow it out to a 2 day job and introduce a lot more chances of creating problems that you did not have in the first place.
4) not usually a safety switch generally just kills the engine stone dead. You check by undoing the cut out wire on the coil which removes all of the controls INCLUNING SHUTTING DOWN THE ENGINE ( get the hint ).
An oil fouled plug will cause a miss , popping and even an engine destroying backfire through the carb.
5) Do not ever even think about replacing the alloy shear key in the flywheel with a power transmission steel key no, no , no, never ever.
#4
M
mr.farmall
Just how many engines have you worked on over the years????? I'm amazed at your knowledge!
once again you pointed to the problem. It appears the head gasket was damaged right were you stated, between the push rod section and the edge of the cylinder. I have attached some photos just to make sure.
1. the block with the gasket in place.
2. the head, without the gasket of course.
3. the block with the gasket removed
4.the gasket, Block side.
from the markings on the block, I can see dark streaming marks were the gases and oil passed through and carbonized on the block. I would imagine it passed oil into the piston on the intake stroke as well.
I'll get a new gasket tomorrow and go from their.
any other suggestions?the valve lashing was intake= 6/1000 and exhaust = 8/1000. I'm not very knowledgeable about the stem seats or seals.
Thanks Rex
M
mr.farmall
Ten to one says you have a blown head gasket. Pull the head and take a look. Will be blown between the cylinder wall and the push rod cavity.
Just how many engines have you worked on over the years????? I'm amazed at your knowledge!
once again you pointed to the problem. It appears the head gasket was damaged right were you stated, between the push rod section and the edge of the cylinder. I have attached some photos just to make sure.
1. the block with the gasket in place.
2. the head, without the gasket of course.
3. the block with the gasket removed
4.the gasket, Block side.
from the markings on the block, I can see dark streaming marks were the gases and oil passed through and carbonized on the block. I would imagine it passed oil into the piston on the intake stroke as well.
I'll get a new gasket tomorrow and go from their.
any other suggestions?the valve lashing was intake= 6/1000 and exhaust = 8/1000. I'm not very knowledgeable about the stem seats or seals.
Thanks Rex
Attachments
#5
B
bertsmobile1
B
bertsmobile1
Before you replace the head lap it on a sheet of glass with some fine wet & dry paper oiled.
Check the block carefully it may have gone hollow where the gasket was leaking.
Home owners have difficulty facing the block but a little Davcon Alloy paste will go a long away if it is not flat.
Check the block carefully it may have gone hollow where the gasket was leaking.
Home owners have difficulty facing the block but a little Davcon Alloy paste will go a long away if it is not flat.
#6
M
mr.farmall
Thanks for all the good info Bertsmobil1.
It just makes since what you said about the engine kill wiring. remove it at the engine and all other kill switches become inoperative! good advice for testing it out.
Just a word about the flywheel key, it is designed to have the steel key that's in it. I had one of you engine killing backfires that destroyed the flywheel. It cracked and split right at the flywheel key. It was an expensive fix. the key that it required was a steel key. I tried to use one of the alloy keys in its place, but it sheared on the first start up of the engine in less than a second. That steel key is what the parts store ordered and sold to me when they looked it up. Maybe it's some type of steel/ alloy mix because it's much harder than the regular keys and it sticks to the magnet on the flywheel. Thanks for your concern.
M
mr.farmall
Answers to your questions
5) Do not ever even think about replacing the alloy shear key in the flywheel with a power transmission steel key no, no , no, never ever.
Thanks for all the good info Bertsmobil1.
It just makes since what you said about the engine kill wiring. remove it at the engine and all other kill switches become inoperative! good advice for testing it out.
Just a word about the flywheel key, it is designed to have the steel key that's in it. I had one of you engine killing backfires that destroyed the flywheel. It cracked and split right at the flywheel key. It was an expensive fix. the key that it required was a steel key. I tried to use one of the alloy keys in its place, but it sheared on the first start up of the engine in less than a second. That steel key is what the parts store ordered and sold to me when they looked it up. Maybe it's some type of steel/ alloy mix because it's much harder than the regular keys and it sticks to the magnet on the flywheel. Thanks for your concern.
#7
I
ILENGINE
I
ILENGINE
Clean the mating surfaces off real good. even using fine wet dry paper to smooth the head if needed. Valve clearances should be .004-006 for intake, but I like to run on the narrow side for the valve with the compression release. That thing is sensitive enough to excess clearance without giving it any to play with. and .005-007 for exhaust. middle of the road is fine there.
As far as number of engines I have worked on over the years, I wouldn't even know where to start counting. I overhauled my first briggs engine off o fa tiller at age 8. It sometimes isn't the number of engines that I have worked on, It is more the situation of I tend to get the, what I call problem children in the shop. those are the engines that are hard to track down the problem. And the ones where the customers bring it in, because there were referred by another shop. Or I am the 5th repair shop it has been to because nobody else can fix it.
I almost thought about telling you guys my age, but I think I will let you guys guess. I am having a birthday next week, so I think it would be fun to see if you guys can guess how old I am.
As far as number of engines I have worked on over the years, I wouldn't even know where to start counting. I overhauled my first briggs engine off o fa tiller at age 8. It sometimes isn't the number of engines that I have worked on, It is more the situation of I tend to get the, what I call problem children in the shop. those are the engines that are hard to track down the problem. And the ones where the customers bring it in, because there were referred by another shop. Or I am the 5th repair shop it has been to because nobody else can fix it.
I almost thought about telling you guys my age, but I think I will let you guys guess. I am having a birthday next week, so I think it would be fun to see if you guys can guess how old I am.
#8
Michael72
59 ish
Michael72
Clean the mating surfaces off real good. even using fine wet dry paper to smooth the head if needed. Valve clearances should be .004-006 for intake, but I like to run on the narrow side for the valve with the compression release. That thing is sensitive enough to excess clearance without giving it any to play with. and .005-007 for exhaust. middle of the road is fine there.
As far as number of engines I have worked on over the years, I wouldn't even know where to start counting. I overhauled my first briggs engine off o fa tiller at age 8. It sometimes isn't the number of engines that I have worked on, It is more the situation of I tend to get the, what I call problem children in the shop. those are the engines that are hard to track down the problem. And the ones where the customers bring it in, because there were referred by another shop. Or I am the 5th repair shop it has been to because nobody else can fix it.
I almost thought about telling you guys my age, but I think I will let you guys guess. I am having a birthday next week, so I think it would be fun to see if you guys can guess how old I am.
59 ish
#10
B
bertsmobile1
Don't know what you got sold buy the shear key is designed to do just that,
Shear when something jambs the PTO so as to avoid damage to the engine,
If the key shears too easy the the flywheel is not done up tight enough.
B
bertsmobile1
Thanks for all the good info Bertsmobil1.
It just makes since what you said about the engine kill wiring. remove it at the engine and all other kill switches become inoperative! good advice for testing it out.
Just a word about the flywheel key, it is designed to have the steel key that's in it. I had one of you engine killing backfires that destroyed the flywheel. It cracked and split right at the flywheel key. It was an expensive fix. the key that it required was a steel key. I tried to use one of the alloy keys in its place, but it sheared on the first start up of the engine in less than a second. That steel key is what the parts store ordered and sold to me when they looked it up. Maybe it's some type of steel/ alloy mix because it's much harder than the regular keys and it sticks to the magnet on the flywheel. Thanks for your concern.
Don't know what you got sold buy the shear key is designed to do just that,
Shear when something jambs the PTO so as to avoid damage to the engine,
If the key shears too easy the the flywheel is not done up tight enough.
#11
I
ILENGINE
I
ILENGINE
Hey Bert, this will go against everything we have ever been told about flywheel keys. The engine in question has a advance parts bulletin tied to it which increases the flywheel nut/bolt torque to 110 ft/lb and uses the 796335 STEEL flywheel key.
#13
M
mr.farmall
I see now!! you'll be 39, just like my wife!
But you have the wisdom of experience no matter what your age!!
As for the head gasket, I just got it today, I'll have it in tonight. Wish me well. And I'll increase the torque from 100 ft lbs to 110 ft lbs. Thanks for the update.
Rex
M
mr.farmall
As of this coming week I will have 18 more years before I get medicare.
I see now!! you'll be 39, just like my wife!
But you have the wisdom of experience no matter what your age!!
As for the head gasket, I just got it today, I'll have it in tonight. Wish me well. And I'll increase the torque from 100 ft lbs to 110 ft lbs. Thanks for the update.
Rex
#14
B
bertsmobile1
Well, that is why I am here, to learn what I do not know.
i find it supprising as tappers are supposed to be self locking and have been so since 1882 which is the earliest use of tappers I have come across.
Some of the vintage bikes I play with do use a soft steel key in hardened slots.
All the mowers I have pulled down ( about 1 % of the number you would appear to have done ) had an alloy key and that is the only one I can get from my aftermarket suppliers so i will need to look into getting some .
B
bertsmobile1
Hey Bert, this will go against everything we have ever been told about flywheel keys. The engine in question has a advance parts bulletin tied to it which increases the flywheel nut/bolt torque to 110 ft/lb and uses the 796335 STEEL flywheel key.
Well, that is why I am here, to learn what I do not know.
i find it supprising as tappers are supposed to be self locking and have been so since 1882 which is the earliest use of tappers I have come across.
Some of the vintage bikes I play with do use a soft steel key in hardened slots.
All the mowers I have pulled down ( about 1 % of the number you would appear to have done ) had an alloy key and that is the only one I can get from my aftermarket suppliers so i will need to look into getting some .
#15
M
mr.farmall
Well, that didn't go quite as I had expected!
I have replaced the head gasket, now with every thing back in place, the leak down tests look much better, no more noise through the body of the engine via the oil filler port.
I started the engine and it run great. I took it a short distance and turned it off to wash everything down. Now it won't start up again. let it sit for a couple of hours and tried it again, it ran ok for 10 second, then started popping badly and stopped. Put it in the garage to sit over the weekend and tried it again Monday morning, still just pops and sputters and backfires into the carburetor, but will not start.
Thinking the timing was out, I checked the flywheel key. It is not a problem, solid and not partially sheared. Then I turned to the electronics. I went through every lead on every switch including the key switch and seat switch. All were good, no opens nor grounds (except were they should be). Tried to create a problem through each contact of each switch(Isolating only one at a time) with pushing, pulling and applying pressure, but could find no troubles.
I disconnected the kill wire to the engine, (thanks for the tip Bert), and run a by pass jumper to the fuel solenoid, Still the same occasional back fire, but not even close to starting.
Pulled the new spark plug, it is black with soot again after only 20-30 seconds of running. preformed the leak down test again. Have good result with only about 20% loss on the top dead center position.
This engine must have a compression release on the intake valve during the compression stroke since the leak down doesn't show good results until the last 60 degrees of the 180 degrees of the compression stroke. then it looks great for the last 60 degrees of the stroke and the next 170 out of the 180 degree of the power stroke befor the exhaust starts to open.
I'm not sure what to do next, the valves seem to be sealing OK, the head is no longer leaking, but their is soot on the plug after just a very short run time.
any help would greatly be appreciated.
thanks Rex
M
mr.farmall
Ten to one says you have a blown head gasket. Pull the head and take a look. Will be blown between the cylinder wall and the push rod cavity.
Well, that didn't go quite as I had expected!
I have replaced the head gasket, now with every thing back in place, the leak down tests look much better, no more noise through the body of the engine via the oil filler port.
I started the engine and it run great. I took it a short distance and turned it off to wash everything down. Now it won't start up again. let it sit for a couple of hours and tried it again, it ran ok for 10 second, then started popping badly and stopped. Put it in the garage to sit over the weekend and tried it again Monday morning, still just pops and sputters and backfires into the carburetor, but will not start.
Thinking the timing was out, I checked the flywheel key. It is not a problem, solid and not partially sheared. Then I turned to the electronics. I went through every lead on every switch including the key switch and seat switch. All were good, no opens nor grounds (except were they should be). Tried to create a problem through each contact of each switch(Isolating only one at a time) with pushing, pulling and applying pressure, but could find no troubles.
I disconnected the kill wire to the engine, (thanks for the tip Bert), and run a by pass jumper to the fuel solenoid, Still the same occasional back fire, but not even close to starting.
Pulled the new spark plug, it is black with soot again after only 20-30 seconds of running. preformed the leak down test again. Have good result with only about 20% loss on the top dead center position.
This engine must have a compression release on the intake valve during the compression stroke since the leak down doesn't show good results until the last 60 degrees of the 180 degrees of the compression stroke. then it looks great for the last 60 degrees of the stroke and the next 170 out of the 180 degree of the power stroke befor the exhaust starts to open.
I'm not sure what to do next, the valves seem to be sealing OK, the head is no longer leaking, but their is soot on the plug after just a very short run time.
any help would greatly be appreciated.
thanks Rex
#16
I
ILENGINE
I
ILENGINE
Remove the air filter and see if the running improves. If so then make sure the air filter isn't clogged with oil, dirt, etc. If that checks out OK then pull the dipstick ans smell the oil for gas smell.
If those two things check out then we could be dealing with a carb problem. Just don't loose the jet when it falls out of the bottom of the plastic emulsion tube.
If those two things check out then we could be dealing with a carb problem. Just don't loose the jet when it falls out of the bottom of the plastic emulsion tube.
#17
M
mr.farmall
Thanks once again for the info.
The oil smells like oil and the air filter is clean. it doesn't start so I can't tell if it improves it or not with the air filter on or off.
I disconnected and removed the carburetor. (Nikki version for the 31000 model). Upon dismantling it, I could see the jet imbedded in the bottom of the plastic dip tube, but I'm thinking it is the shut off valve for the electronic solenoid or maybe it functions as both the shut off and the jet, but it was secure. Looking at the info on the service manual, it appears that the spring that goes between the bottom end of the dip tub and the bottom of the bowel is missing.(The manual say to keep an eye out for the spring because it just fall off and can easily be lost). The dip tube connects to the shut off solenoid with the spring in between the two. You have probably seen this before, but if you would like a picture, I'll post one.
This carburetor is a lot different than most lawn mower carbs I have seen, it has a plastic insert with various passages and a very complex o-ring type seal between the plastic and the metal of the carburetor. It covers the entire top of the bowel which is also the bottom of the carburetor body. The gas intake float connect on the bottom of this insert and hangs into the bowel around the plastic dip tub of this insert.
The carburetor looks really clean at first glance, but I'll clean it anyway. I'll see what I can get for parts on the carburetor. Any other suggestions are welcomed.
One question more, torquing down the flywheel bolt is not easy. trying to hold the fly wheel and putting 110 foot lbs on the bolt just doesn't seem to be working. Is there a method that will hold the flywheel in place so that the bolt can be torqued correctly?
Thanks Rex
edit note;
the B&S parts manual 31e877-1502-g1 doesn't show this spring while the service manual does. Now I'm confused!
M
mr.farmall
Remove the air filter and see if the running improves. If so then make sure the air filter isn't clogged with oil, dirt, etc. If that checks out OK then pull the dipstick ans smell the oil for gas smell.
If those two things check out then we could be dealing with a carb problem. Just don't loose the jet when it falls out of the bottom of the plastic emulsion tube.
Thanks once again for the info.
The oil smells like oil and the air filter is clean. it doesn't start so I can't tell if it improves it or not with the air filter on or off.
I disconnected and removed the carburetor. (Nikki version for the 31000 model). Upon dismantling it, I could see the jet imbedded in the bottom of the plastic dip tube, but I'm thinking it is the shut off valve for the electronic solenoid or maybe it functions as both the shut off and the jet, but it was secure. Looking at the info on the service manual, it appears that the spring that goes between the bottom end of the dip tub and the bottom of the bowel is missing.(The manual say to keep an eye out for the spring because it just fall off and can easily be lost). The dip tube connects to the shut off solenoid with the spring in between the two. You have probably seen this before, but if you would like a picture, I'll post one.
This carburetor is a lot different than most lawn mower carbs I have seen, it has a plastic insert with various passages and a very complex o-ring type seal between the plastic and the metal of the carburetor. It covers the entire top of the bowel which is also the bottom of the carburetor body. The gas intake float connect on the bottom of this insert and hangs into the bowel around the plastic dip tub of this insert.
The carburetor looks really clean at first glance, but I'll clean it anyway. I'll see what I can get for parts on the carburetor. Any other suggestions are welcomed.
One question more, torquing down the flywheel bolt is not easy. trying to hold the fly wheel and putting 110 foot lbs on the bolt just doesn't seem to be working. Is there a method that will hold the flywheel in place so that the bolt can be torqued correctly?
Thanks Rex
edit note;
the B&S parts manual 31e877-1502-g1 doesn't show this spring while the service manual does. Now I'm confused!
#18
I
ILENGINE
I
ILENGINE
Some of the carbs had the spring you are talking about and other didn't I just went through the same thing a few months ago thinking I had dropped the spring. the jet I am talking about sits up inside the plastic piece you were talking about. It goes in ffrom the top, and will fall out if you turn the plastic piece upside down.
As far as torquing the flywheel the briggs tool for holding the flywheel is a strap wrench. And even then it is fun holding the strap wrench in one hand and trying to pull the torque wrench with the other.
As far as torquing the flywheel the briggs tool for holding the flywheel is a strap wrench. And even then it is fun holding the strap wrench in one hand and trying to pull the torque wrench with the other.
#19
M
mr.farmall
Thursday
I've taken the carburetor off to clean it on Tuesday. It looked very clean, almost as if it were new. Very carefully taking it apart with the aid of the service manual from Briggs. I placed it in an ultrasonic cleaner then dried it out with air in a cloth just in case something came loose or was blown out. nothing did.
While it was apart, I removed the heads to check the valves once more, they had some build up but were good. I cleaned them and then lapped them to make sure I could see a good seal around the entire valve. Both valves looked good.
As for the Carburetor, it's pristine clean. I placed the float in a cup of water and it floats OK. The little shut off needle looked good and had a pointed rubber end on it, so I think is was good also.
Now the engine's back together and the carburetor is back in place.
The engine did start this time, but with great effort and many back fires. Once started, it stopped backfiring but had an occasional miss until the governor called for more throttle, then it would backfire and take off again until a few moments later (5-10 seconds) when the governor opened the throttle again. This lasted for about 4 minutes then three or four back fires in a row and the engine stopped.
It will start again, but with lots of backfiring.
This was tested with the kill lead to the engine disconnected and a 12v supply directly to the fuel solenoid to operate it. This was how the engine acted when I started working on it.
new head gasket
leak down test looks good
valves are good
timing key OK
wiring checks out
carburetor clean.
New spark plug
clean air filter
I'm really at a loss of what to check next!
thanks for any help
Rex
M
mr.farmall
Remove the air filter and see if the running improves. If so then make sure the air filter isn't clogged with oil, dirt, etc. If that checks out OK then pull the dipstick ans smell the oil for gas smell.
If those two things check out then we could be dealing with a carb problem. Just don't loose the jet when it falls out of the bottom of the plastic emulsion tube.
Thursday
I've taken the carburetor off to clean it on Tuesday. It looked very clean, almost as if it were new. Very carefully taking it apart with the aid of the service manual from Briggs. I placed it in an ultrasonic cleaner then dried it out with air in a cloth just in case something came loose or was blown out. nothing did.
While it was apart, I removed the heads to check the valves once more, they had some build up but were good. I cleaned them and then lapped them to make sure I could see a good seal around the entire valve. Both valves looked good.
As for the Carburetor, it's pristine clean. I placed the float in a cup of water and it floats OK. The little shut off needle looked good and had a pointed rubber end on it, so I think is was good also.
Now the engine's back together and the carburetor is back in place.
The engine did start this time, but with great effort and many back fires. Once started, it stopped backfiring but had an occasional miss until the governor called for more throttle, then it would backfire and take off again until a few moments later (5-10 seconds) when the governor opened the throttle again. This lasted for about 4 minutes then three or four back fires in a row and the engine stopped.
It will start again, but with lots of backfiring.
This was tested with the kill lead to the engine disconnected and a 12v supply directly to the fuel solenoid to operate it. This was how the engine acted when I started working on it.
new head gasket
leak down test looks good
valves are good
timing key OK
wiring checks out
carburetor clean.
New spark plug
clean air filter
I'm really at a loss of what to check next!
thanks for any help
Rex
#20
B
bertsmobile1
B
bertsmobile1
Check for air leaks,
Spray some ing like WD 40 FROM A TRIGGER PACK ) all around the carb to engine area.
If it makes a difference then you have an air leak.
Spray some ing like WD 40 FROM A TRIGGER PACK ) all around the carb to engine area.
If it makes a difference then you have an air leak.
#21
M
mr.farmall
Thanks Bert for the suggestion on the air leak.
I started to look at it tonight with intentions to do your spray test, then got the thought that I should just check the fuel pump, since it was one of the few things I haven't checked. With the fuel line off in a can, It seemed to work as it should. I put it back together to start the spray test, but the engine started and ran perfectly; no hesitation in starting and no backfiring. it ran constant and the governor wasn't working back and forth to keep it running. It was smooth at all speeds.
I didn't get to your test, but I'm not very satisfied that it just started working. I don't like unanswered results. So my question to both you and ILLengine or anyone else that might be following this post, is; could just the fuel pump have caused a lot of the backfiring that was previously happening? Could just having the pump run 1/2 cup of fuel into a can, could this have corrected the problem? Do these air operated fuel pumps have a track record of problems? and should I just try changing it out. (I really don't like to just change things out without a reason).
Thanks again sooooo much for your assistance. I feel blessed to have had your help.
I'll put it through a good run tomorrow and see if the trouble is really gone!
Thanks Rex
M
mr.farmall
Check for air leaks,
Spray some ing like WD 40 FROM A TRIGGER PACK ) all around the carb to engine area.
If it makes a difference then you have an air leak.
Thanks Bert for the suggestion on the air leak.
I started to look at it tonight with intentions to do your spray test, then got the thought that I should just check the fuel pump, since it was one of the few things I haven't checked. With the fuel line off in a can, It seemed to work as it should. I put it back together to start the spray test, but the engine started and ran perfectly; no hesitation in starting and no backfiring. it ran constant and the governor wasn't working back and forth to keep it running. It was smooth at all speeds.
I didn't get to your test, but I'm not very satisfied that it just started working. I don't like unanswered results. So my question to both you and ILLengine or anyone else that might be following this post, is; could just the fuel pump have caused a lot of the backfiring that was previously happening? Could just having the pump run 1/2 cup of fuel into a can, could this have corrected the problem? Do these air operated fuel pumps have a track record of problems? and should I just try changing it out. (I really don't like to just change things out without a reason).
Thanks again sooooo much for your assistance. I feel blessed to have had your help.
I'll put it through a good run tomorrow and see if the trouble is really gone!
Thanks Rex
#22
B
bertsmobile1
B
bertsmobile1
There is nothing to an impulse fuel pump.
hose from the sump on one side of a diaphram spring on the other and a pair of one way valves.
Problems
1) connected the wrong way round
2) leaky, perished hoses
3) blocked air vent
4) very rare rupured diaphragm
They usually do not give a problem till they don't work.
The pump can move about 10 times the fuel that the engine can consume.
So usually they either work or they don't work
hose from the sump on one side of a diaphram spring on the other and a pair of one way valves.
Problems
1) connected the wrong way round
2) leaky, perished hoses
3) blocked air vent
4) very rare rupured diaphragm
They usually do not give a problem till they don't work.
The pump can move about 10 times the fuel that the engine can consume.
So usually they either work or they don't work
#23
I
ILENGINE
I
ILENGINE
Like Bert said, they either work or they don't most of the time. I have seen a few exceptions to the rule though. If the fuel pump wasn't putting out enough fuel it could cause the backfiring because the engine is running lean. Now by allowing the pump to move fuel unrestricted could of cleared when ever was causing the lack of fuel flow. this could be permanent or temporary, Either way if it messes up again just replace the pump.
I have seen the vacuum pump on briggs stop working when the engine would get hot. I have had brand new Kohler fuel pumps not work out of the box, until you actually got fuel into the pump to wet the diaphragms and get it working So there are a few exceptions to what would be normal.
I have seen the vacuum pump on briggs stop working when the engine would get hot. I have had brand new Kohler fuel pumps not work out of the box, until you actually got fuel into the pump to wet the diaphragms and get it working So there are a few exceptions to what would be normal.
#24
M
mr.farmall
Thanks Bert;
Australia is a long way away, but your information is Golden.
Rex
M
mr.farmall
There is nothing to an impulse fuel pump.
They usually do not give a problem till they don't work.
Thanks Bert;
Australia is a long way away, but your information is Golden.
Rex
#25
M
mr.farmall
Thanks so much again, all you have posted must represent lots of experience and knowledge. Thanks for sharing it.
P.S. If I were back east, I would mind spending some of the retired timeto work with you a month or two!! Maybe something would rub off!
Rex
M
mr.farmall
Like Bert said, they either work or they don't most of the time. I have seen a few exceptions to the rule though. If the fuel pump wasn't putting out enough fuel it could cause the backfiring because the engine is running lean. Now by allowing the pump to move fuel unrestricted could of cleared when ever was causing the lack of fuel flow. this could be permanent or temporary, Either way if it messes up again just replace the pump.
Thanks so much again, all you have posted must represent lots of experience and knowledge. Thanks for sharing it.
P.S. If I were back east, I would mind spending some of the retired timeto work with you a month or two!! Maybe something would rub off!
Rex
#26
B
bertsmobile1
B
bertsmobile1
Rarely get a roblem with impulse pumps, however those mechanicals on the CH Kohlers are the bane of my life.
By now I would expect that I would check them first , particularly with the magic over filling oil syndrome but nope, usually the last thing I look at
By now I would expect that I would check them first , particularly with the magic over filling oil syndrome but nope, usually the last thing I look at
#27
M
mr.farmall
M
mr.farmall
The engine stared and ran well today. I think it's back in service.
I had such a hard time finding the correct wiring schematic for this mower that I ended up metering out all the wiring and making a schematic. I think I'll post it separately for anyone else that might need it.
thanks again everyone.
Rex
I had such a hard time finding the correct wiring schematic for this mower that I ended up metering out all the wiring and making a schematic. I think I'll post it separately for anyone else that might need it.
thanks again everyone.
Rex