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25 Hp Kohler Gravely... black smoke under load.. loss of power??
#1
G
gunner181
G
gunner181
Newbie here...
Hello all...
I have a 60" Gravely with a 25HP Kohler on it.. The machine idles great, starts fine..ect... But when you start mowing and cut more than 1/2 in it starts to bog down... IF you cut a bit more than that you start to see the big black cloud.... I hate throwing parts at these things!! My brother in law who is a mechanic thought it was a bad plug wire ( you have to buy the module b/c the wire is laminated to it) no real change??? We did a compression test and found 150 # on both sides.
model CV 25S
Spec no 69536
DISPL 725
the manual says to do a leak down test... ? Does that make our compression test inaccurate?
This is very annoying seeing that I cant really cut the grass with any length to it... The engine does have a few hrs on it (1800)... His next idea was to check the no load RPm then move to the carb.
If anyone could kinda explain what they think might be happening that would be fantastic!!
Thanks so much!
Hello all...
I have a 60" Gravely with a 25HP Kohler on it.. The machine idles great, starts fine..ect... But when you start mowing and cut more than 1/2 in it starts to bog down... IF you cut a bit more than that you start to see the big black cloud.... I hate throwing parts at these things!! My brother in law who is a mechanic thought it was a bad plug wire ( you have to buy the module b/c the wire is laminated to it) no real change??? We did a compression test and found 150 # on both sides.
model CV 25S
Spec no 69536
DISPL 725
the manual says to do a leak down test... ? Does that make our compression test inaccurate?
This is very annoying seeing that I cant really cut the grass with any length to it... The engine does have a few hrs on it (1800)... His next idea was to check the no load RPm then move to the carb.
If anyone could kinda explain what they think might be happening that would be fantastic!!
Thanks so much!
#2
I
ILENGINE
I
ILENGINE
Black smoke means too much fuel. I would say since it happens under load the most likely area would be to look at the high speed jet in the carb. May off came out or has worn over time causing a rich run conditon. Could be an air filter problem also. May look clean but be partially clogged. I have seen it on more than one occation.
#3
Briana
Briana
Hey there - WELCOME to LMF!
I moved your thread to the Gravely Forum. :smile:
I moved your thread to the Gravely Forum. :smile:
#4
R
Richard-TX
R
Richard-TX
It sounds like the carb float may be defective. What happens is the plastic float deteriorates and the float will start absorbing gasoline and that will make it run too rich. I would start with that. Might as well change the needle and seat too.
#5
G
gunner181
G
gunner181
Hey there...
I was wondering if someone could help me figure out this problem. I am the one who had the original problem "Black smoke under load..loss of power"... to make a long story short I took it to the local gravely dealer, we ended up throwing a bunch of things at it, did a leakdown (it was fine) head gasket, plugs, fuel pump. ect....
The thing that fixed it was the shut off solenoid on the carburater?? Im not sure I understand that concept? I thought that its only job was to shut off fuel to carb when engine is shutdown? Anyways.. it cuts pretty good now!
.. Here is the latest.. It seemed to slowly work its way into a backfiring condition. I mean at the end of last season it would do a slight pop every so often.. IT cut fine for the first few cuts this season. Now its backfiring more and more.. They are somewhat louder and I noticed a black cloud on some backfiring..
I tried a new set of plugs and I took the air filter off for a very short period.
I cut last night and it has power to cut.. I noticed when it was backfiring say when I turned it would have a slight loss of power...
ANy ideas?
I was wondering if someone could help me figure out this problem. I am the one who had the original problem "Black smoke under load..loss of power"... to make a long story short I took it to the local gravely dealer, we ended up throwing a bunch of things at it, did a leakdown (it was fine) head gasket, plugs, fuel pump. ect....
The thing that fixed it was the shut off solenoid on the carburater?? Im not sure I understand that concept? I thought that its only job was to shut off fuel to carb when engine is shutdown? Anyways.. it cuts pretty good now!
.. Here is the latest.. It seemed to slowly work its way into a backfiring condition. I mean at the end of last season it would do a slight pop every so often.. IT cut fine for the first few cuts this season. Now its backfiring more and more.. They are somewhat louder and I noticed a black cloud on some backfiring..
I tried a new set of plugs and I took the air filter off for a very short period.
I cut last night and it has power to cut.. I noticed when it was backfiring say when I turned it would have a slight loss of power...
ANy ideas?
#6
R
Richard-TX
R
Richard-TX
Since it is running too rich (black smoke) that points to the carb. The backfire and fuel cutoff solenoid are likely related. The idea behind the fuel solenoid is to shut off the fuel when the ignition is shut off. It helps to stop that afterrun pop or backfire on shutdown. How that could cause a too rich run condition does not make sense. I think there is some bit of information missing.
I have had issues with some of the later Nikki carbs particularly the ones with the accelerator pump. If the metering spring and plunger get lost, it will dump excess fuel into the carb when running causing intermittent black smoke and rough running. This info may not apply to your Kohler.
Carbs are getting cheap. I bought a carb for a Honda recently and it cost me a whopping $18. New Nikki single barrel carbs should run about $125.
I think that you are looking in the right area, but the carb is still not right. If I were you I would try a new carb. I would also look at the safety system as an intermittent loss of spark can cause backfires.
I have had issues with some of the later Nikki carbs particularly the ones with the accelerator pump. If the metering spring and plunger get lost, it will dump excess fuel into the carb when running causing intermittent black smoke and rough running. This info may not apply to your Kohler.
Carbs are getting cheap. I bought a carb for a Honda recently and it cost me a whopping $18. New Nikki single barrel carbs should run about $125.
I think that you are looking in the right area, but the carb is still not right. If I were you I would try a new carb. I would also look at the safety system as an intermittent loss of spark can cause backfires.
#7
WISCOPROUD
WISCOPROUD
sounds like ignition to me
#8
R
Rivets
R
Rivets
Don't buy a new carb yet. I think it just might be the fuel solenoid, telling you what's wrong. Just reread the entire post twice then remembered a problem I had a couple of years ago. Check the wiring going to the fuel solenoid and. I think if you look and feel carefully you are going to find a cracked or partially broken wire. What is happening is the wire will short when you hit a bump or turn. When this happens it will kill the ignition circuit for an instant, meaning no spark. Then it will reconnect and have spark. During the no spark period some raw fuel will enter the cylinder causing a rich mixture, and then when the plug fires a lot of black smoke. It will also backfire with this problem, because the rich fuel is still burning when the exhaust valve opens. You will have to look very closely with your fingers. Go slow and be patient. Go luck.
#9
G
gunner181
G
gunner181
OK... I gotta give an update..
Checked over the entire engine looking for a frayed/broken wire ect.. at first no luck.. So I was able to find a friend who had an identical engine (which ran fine) who was willing to swap carbs to eliminate the whole carb issue.. Swapped the carbs.. still poping and backfiring... Grrrrr.... So we decided to pull the valve covers and check the valve clearance... There was zero clearance from the rocker to the valve stem..?? (I also need to find out how to check the valve clearance cuz we couldnt fit the smallest size feeler between rocker and valve anywhere in the stoke, tried TDC... no gap at all.. then tried everywhere in stoke) So we pissed around and kinda noticed that one of the springs on the intake valve on one side wasnt compressing the same as the other side?? We removed the rocker and pushrod and swapped the rods with the exhaust.. (both rods looked identical). (not sure why we did that).... While We had it apart I was looking closely for a broken wire ect... I found a taped wire that would normally rest on the engine cover, I pulled the tape off and it was frayed, wire was still intact but insulation was peeled?? We cut it and put a butt connector with shrink wrap. It was a purple wire from the voltage regulator... So after all this we put everything back and fired the engine. I cut for approx 40 min no backfiring??? I then cut again that night for another hr and no backfiring? "Touch wood" engine runs better than ever?
WTF?? ... .. We never found a smoking gun.... I guess if the backfiring returns it is a valve issue... if it doesnt it was the wire?? I dont feel comfortable... I wish we found a smoking gun! Then Id know we nailed it....
Any comments....
Thanks for all the help!
Checked over the entire engine looking for a frayed/broken wire ect.. at first no luck.. So I was able to find a friend who had an identical engine (which ran fine) who was willing to swap carbs to eliminate the whole carb issue.. Swapped the carbs.. still poping and backfiring... Grrrrr.... So we decided to pull the valve covers and check the valve clearance... There was zero clearance from the rocker to the valve stem..?? (I also need to find out how to check the valve clearance cuz we couldnt fit the smallest size feeler between rocker and valve anywhere in the stoke, tried TDC... no gap at all.. then tried everywhere in stoke) So we pissed around and kinda noticed that one of the springs on the intake valve on one side wasnt compressing the same as the other side?? We removed the rocker and pushrod and swapped the rods with the exhaust.. (both rods looked identical). (not sure why we did that).... While We had it apart I was looking closely for a broken wire ect... I found a taped wire that would normally rest on the engine cover, I pulled the tape off and it was frayed, wire was still intact but insulation was peeled?? We cut it and put a butt connector with shrink wrap. It was a purple wire from the voltage regulator... So after all this we put everything back and fired the engine. I cut for approx 40 min no backfiring??? I then cut again that night for another hr and no backfiring? "Touch wood" engine runs better than ever?
WTF?? ... .. We never found a smoking gun.... I guess if the backfiring returns it is a valve issue... if it doesnt it was the wire?? I dont feel comfortable... I wish we found a smoking gun! Then Id know we nailed it....
Any comments....
Thanks for all the help!
#10
R
Rivets
R
Rivets
I would say you found your problem. The purple wire you repaired is your charging wire and if it was shorting out it could have shown the symptoms you described. The following website is a downloadable service manual for your engine. It might help. http://www.kohler-engine-parts.opeengines.com/pub/SM_2469007_CV17_thur_CV750_REV1_12.pdf
#11
M
michaelhawkins1
Here is what I've done so far... new plugs, air filter, fuel pump, fuel lines. I'm thinking of getting a new carb 30.00, that would take care of solenoid, float and highspeed jet. I'm really struggling here and would appreciate any advice, thanks Michael
M
michaelhawkins1
Hey Rivets... this post is almost to a Tee what mine is doing. (Exmark 25hp Kohler command) just started doing this a week ago, Slight black smoke under load, will backfire occasionally, Loss of power drastically starting to mow anything. will sutter when I hit a bump and puff a black smoke like it's over full. still has problems starting have to choke and then quickly release choke.Don't buy a new carb yet. I think it just might be the fuel solenoid, telling you what's wrong. Just reread the entire post twice then remembered a problem I had a couple of years ago. Check the wiring going to the fuel solenoid and. I think if you look and feel carefully you are going to find a cracked or partially broken wire. What is happening is the wire will short when you hit a bump or turn. When this happens it will kill the ignition circuit for an instant, meaning no spark. Then it will reconnect and have spark. During the no spark period some raw fuel will enter the cylinder causing a rich mixture, and then when the plug fires a lot of black smoke. It will also backfire with this problem, because the rich fuel is still burning when the exhaust valve opens. You will have to look very closely with your fingers. Go slow and be patient. Go luck.
Here is what I've done so far... new plugs, air filter, fuel pump, fuel lines. I'm thinking of getting a new carb 30.00, that would take care of solenoid, float and highspeed jet. I'm really struggling here and would appreciate any advice, thanks Michael
#12
M
michaelhawkins1
M
michaelhawkins1
Hey gunner... could you give me an update on your situation... it sounds Identical to mine. thanks MichaelOK... I gotta give an update..
Checked over the entire engine looking for a frayed/broken wire ect.. at first no luck.. So I was able to find a friend who had an identical engine (which ran fine) who was willing to swap carbs to eliminate the whole carb issue.. Swapped the carbs.. still poping and backfiring... Grrrrr.... So we decided to pull the valve covers and check the valve clearance... There was zero clearance from the rocker to the valve stem..?? (I also need to find out how to check the valve clearance cuz we couldnt fit the smallest size feeler between rocker and valve anywhere in the stoke, tried TDC... no gap at all.. then tried everywhere in stoke) So we pissed around and kinda noticed that one of the springs on the intake valve on one side wasnt compressing the same as the other side?? We removed the rocker and pushrod and swapped the rods with the exhaust.. (both rods looked identical). (not sure why we did that).... While We had it apart I was looking closely for a broken wire ect... I found a taped wire that would normally rest on the engine cover, I pulled the tape off and it was frayed, wire was still intact but insulation was peeled?? We cut it and put a butt connector with shrink wrap. It was a purple wire from the voltage regulator... So after all this we put everything back and fired the engine. I cut for approx 40 min no backfiring??? I then cut again that night for another hr and no backfiring? "Touch wood" engine runs better than ever?
WTF?? ... .. We never found a smoking gun.... I guess if the backfiring returns it is a valve issue... if it doesnt it was the wire?? I dont feel comfortable... I wish we found a smoking gun! Then Id know we nailed it....
Any comments....
Thanks for all the help!
#13
R
Rivets
R
Rivets
Did you read gunners post #9. Start there and then post back. Do you know this thread is 9 years old, I doubt gunner is around any more.