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Old B&S engine won't start
#1
J
judge2b
J
judge2b
I have a Briggs and Stratton engine that won't start, model 170402, type 1015-01, code 74032510
Basically it won't start. Fuel is not getting into the engine. I pulled the plug and the valve inside opens and closes but no fuel enters the chamber when I pull start.
I have cleaned out the fuel tank, put fresh fuel in, thoroughly cleaned the fuel bowl/valve assembly, replaced the mesh filter in the bowl, replaced the bowl gasket. I also made sure air can get into the fuel tank via the small hole in the tank cap. There is no fuel filter on the line, only the filter in the bowl.
I have replaced the fuel line.
I have completely taken apart the carb and swapped out all the parts in the carb rebuild kit so all the gaskets and springs and such are new. I also thoroughly cleaned out ever single orifice in the carb. The air cleaner isn't spotless, but its decently clean and there's no gunk in any of the airways going to the carb or the engine body.
I changed the oil and replaced the spark plug. When I attempt to pull start the engine I do get consistent sparks from the plug.
I also cleaned out the breather assembly as well.
Any ideas? I've attached the parts manual as well. Some of the parts don't apply since this is one of the older models obviously.
Basically it won't start. Fuel is not getting into the engine. I pulled the plug and the valve inside opens and closes but no fuel enters the chamber when I pull start.
I have cleaned out the fuel tank, put fresh fuel in, thoroughly cleaned the fuel bowl/valve assembly, replaced the mesh filter in the bowl, replaced the bowl gasket. I also made sure air can get into the fuel tank via the small hole in the tank cap. There is no fuel filter on the line, only the filter in the bowl.
I have replaced the fuel line.
I have completely taken apart the carb and swapped out all the parts in the carb rebuild kit so all the gaskets and springs and such are new. I also thoroughly cleaned out ever single orifice in the carb. The air cleaner isn't spotless, but its decently clean and there's no gunk in any of the airways going to the carb or the engine body.
I changed the oil and replaced the spark plug. When I attempt to pull start the engine I do get consistent sparks from the plug.
I also cleaned out the breather assembly as well.
Any ideas? I've attached the parts manual as well. Some of the parts don't apply since this is one of the older models obviously.
Attachments
#2
R
Rivets
R
Rivets
Going to ask, what may be seem like dumb questions. Sorry but I'm a visual guy. 1. Have you removed the plug and looked to see that both valves are opening and closing? 2. Have you put your hand over the air horn and turned engine engine over, to verify that you have suction, drawing air through the carb? 3. Have you tried to start the engine by adding fuel or carb cleaner directly into the cylinder? 4. Have you checked to verify that you have fuel in the carb bowl and the float level is set correctly? Here is a service manual which may also help.
http://dl.dropbox.com/u/12502267/B&S Service Manuals/01_270962SingleCylinderLHead.pdf
http://dl.dropbox.com/u/12502267/B&S Service Manuals/01_270962SingleCylinderLHead.pdf
#3
EngineMan
EngineMan
I would do a compression test.
#4
J
judge2b
J
judge2b
1. Have you removed the plug and looked to see that both valves are opening and closing?
When I remove the plug a see 1 valve that's a flap that opens by moving up toward the plug and closes by going back down. There is another valve that looks more like a piston moving up and down inside of a cylinder. I can see it when it rises to to the top of the hole and then it disappears when it sinks down in the hole. There are not 2 valves that look the same though.
2. Have you put your hand over the air horn and turned engine engine over, to verify that you have suction, drawing air through the carb?
Yes
3. Have you tried to start the engine by adding fuel or carb cleaner directly into the cylinder?
I did try with carb cleaner, didn't start
4. Have you checked to verify that you have fuel in the carb bowl and the float level is set correctly?
I manually added fuel to the carb because fuel was not being pulled through the fuel line. That is the only fuel in the carb bowl. As far as the float level being set correctly, how do I adjust the float level?
When I remove the plug a see 1 valve that's a flap that opens by moving up toward the plug and closes by going back down. There is another valve that looks more like a piston moving up and down inside of a cylinder. I can see it when it rises to to the top of the hole and then it disappears when it sinks down in the hole. There are not 2 valves that look the same though.
2. Have you put your hand over the air horn and turned engine engine over, to verify that you have suction, drawing air through the carb?
Yes
3. Have you tried to start the engine by adding fuel or carb cleaner directly into the cylinder?
I did try with carb cleaner, didn't start
4. Have you checked to verify that you have fuel in the carb bowl and the float level is set correctly?
I manually added fuel to the carb because fuel was not being pulled through the fuel line. That is the only fuel in the carb bowl. As far as the float level being set correctly, how do I adjust the float level?
#5
J
judge2b
J
judge2b
I just found some sediment that had collected on the mesh filter above the fuel sediment bowl that wasn't there before. Now I have free flowing fuel to the carb but still not seeing fuel in the chamber when I pull the plug. Also tried to start with carb cleaner in the chamber again: nothing.
#7
J
judge2b
Ok, dry compression test shows it holding at 51 psi. 9 minutes later it was still at 50 psi. I couldn't find a pressure value in that repair manual because it calls for using some special B&S gauges with color codes or something...
J
judge2b
I would do a compression test.
Ok, dry compression test shows it holding at 51 psi. 9 minutes later it was still at 50 psi. I couldn't find a pressure value in that repair manual because it calls for using some special B&S gauges with color codes or something...
#8
R
Rivets
R
Rivets
How did you do your compression test. Did you: install tester------turn the engine over through at least 4 complete cycles------take a reading and repeat a second time. Doing it only once does not give an accurate reading. If the reading comes up low, you should repeat the test with a small amount of oil to see if the reading go up. It they do, it is an indication of bad rings. There is no set compression spec for most engines, due to the compression release mechanism. What I look for is a reading of about 90 what testing with a recoil starter and 110 with an electric starter.
#9
J
judge2b
Yes I installed the tester, turned the engine over 5 or 6 times, did this at least 2 times, maybe 3 (same reading each time). I didn't try the wet test though, I'll do that.
Also, I did adjust the float so that's set correctly now.
J
judge2b
How did you do your compression test. Did you: install tester------turn the engine over through at least 4 complete cycles------take a reading and repeat a second time. Doing it only once does not give an accurate reading. If the reading comes up low, you should repeat the test with a small amount of oil to see if the reading go up. It they do, it is an indication of bad rings. There is no set compression spec for most engines, due to the compression release mechanism. What I look for is a reading of about 90 what testing with a recoil starter and 110 with an electric starter.
Yes I installed the tester, turned the engine over 5 or 6 times, did this at least 2 times, maybe 3 (same reading each time). I didn't try the wet test though, I'll do that.
Also, I did adjust the float so that's set correctly now.
#10
B
Buckshot 1
B
Buckshot 1
:smile: That being a up draft carb. Check for warping between the the two carb halves. Also check for air leaks around the mounting gaskets. Did you install the gasket between the two carb halves correctly? Instead of a comp test, I would do a leak down test.
#11
J
judge2b
I don't think there's any warping as I made sure the two halves fit tightly all the way around. Although I did notice that it seemed some fuel may have been wicking out between the two halves via the gasket. Is that possible? Or does that mean it's definitely warped?
Air leaks around the mounting gaskets of what? The carb?
Yes I installed the gasket between the two carb halves correctly.
J
judge2b
:smile: That being a up draft carb. Check for warping between the the two carb halves. Also check for air leaks around the mounting gaskets. Did you install the gasket between the two carb halves correctly? Instead of a comp test, I would do a leak down test.
I don't think there's any warping as I made sure the two halves fit tightly all the way around. Although I did notice that it seemed some fuel may have been wicking out between the two halves via the gasket. Is that possible? Or does that mean it's definitely warped?
Air leaks around the mounting gaskets of what? The carb?
Yes I installed the gasket between the two carb halves correctly.
#12
J
judge2b
J
judge2b
Wet compression test (twice) holds solidly at 55 psi. Slightly higher than the dry test (51 psi).
#13
R
Rivets
R
Rivets
Those readings are to low for me, but it does tell me we don't have a ring problem. At this point I'm thinking valves. If you had a cylinder leakdown tester, that would be the next step, but without one you are going to have to remove the head and visually inspect the valve movement.
#14
J
judge2b
Sounds like a plan. What exactly I am I looking for? Just proper seals on the valves when closed?
J
judge2b
Those readings are to low for me, but it does tell me we don't have a ring problem. At this point I'm thinking valves. If you had a cylinder leakdown tester, that would be the next step, but without one you are going to have to remove the head and visually inspect the valve movement.
Sounds like a plan. What exactly I am I looking for? Just proper seals on the valves when closed?
#15
B
Buckshot 1
:smile: Everyone of those style carbs that I have worked on, there was always warpage in the top half. Therefore on the wicking it could be warped or you need to retighten the screws. Mounting gaskets: carb to intake, intake to block., either one could not be sealing. There are two carb kits for that carb, 291763 pre 81 code date NLA and 394693 after code date 81. Which leads me to think, you may have purchased the wrong carb kit.
B
Buckshot 1
I don't think there's any warping as I made sure the two halves fit tightly all the way around. Although I did notice that it seemed some fuel may have been wicking out between the two halves via the gasket. Is that possible? Or does that mean it's definitely warped?
Air leaks around the mounting gaskets of what? The carb?
Yes I installed the gasket between the two carb halves correctly.
:smile: Everyone of those style carbs that I have worked on, there was always warpage in the top half. Therefore on the wicking it could be warped or you need to retighten the screws. Mounting gaskets: carb to intake, intake to block., either one could not be sealing. There are two carb kits for that carb, 291763 pre 81 code date NLA and 394693 after code date 81. Which leads me to think, you may have purchased the wrong carb kit.
#16
J
judge2b
I got a carb kit that contained both sets I believe, although I'd have to check.
J
judge2b
:smile: Everyone of those style carbs that I have worked on, there was always warpage in the top half. Therefore on the wicking it could be warped or you need to retighten the screws. Mounting gaskets: carb to intake, intake to block., either one could not be sealing. There are two carb kits for that carb, 291763 pre 81 code date NLA and 394693 after code date 81. Which leads me to think, you may have purchased the wrong carb kit.
I got a carb kit that contained both sets I believe, although I'd have to check.
#17
J
judge2b
Yep, it contained both, I just used the parts and gaskets that matched the ones I took off.
J
judge2b
I got a carb kit that contained both sets I believe, although I'd have to check.
Yep, it contained both, I just used the parts and gaskets that matched the ones I took off.
#18
R
Rivets
R
Rivets
What you are looking for is: are both the valves opening at the correct time. At the valves fulling closing, we should not be able to twist or move them at all when the piston is half way up on the compression stroke. Are the faces of the valves burnt or have a carbon build up. All this could cause a lose of compression, as well as vacuum on the intake stroke.
#19
J
judge2b
Ok. I opened up the head. The head gasket had absolutely no coating on it so it's possible I was getting low compression by that. There was also a LOT of carbon buildup on the piston and on the intake valve (which would explain why the fuel/air mix isn't getting into the chamber). I'm going to get one of those spring compression tools and take the intake valve out, completely clean the carbon off and reinstall it. I'm also going to put a new head gasket on. The piston appears perfectly aligned parallel to the valve opening and not worn where it seals to the opening, I just need to clean off all the carbon around the valve opening so that it closes all the way.
When the piston is halfway up the compression stroke I cannot move or rotate the valves at all.
Can I get away with not replacing the intake valve since it appears to be the carbon buildup that's the problem, or is it highly likely that the valve is damaged and I just can't see it?
Also, apparently on this model there is no intake valve seal, or it's built in somehow otherwise I would have just replaced that to be sure.
J
judge2b
What you are looking for is: are both the valves opening at the correct time. At the valves fulling closing, we should not be able to twist or move them at all when the piston is half way up on the compression stroke. Are the faces of the valves burnt or have a carbon build up. All this could cause a lose of compression, as well as vacuum on the intake stroke.
Ok. I opened up the head. The head gasket had absolutely no coating on it so it's possible I was getting low compression by that. There was also a LOT of carbon buildup on the piston and on the intake valve (which would explain why the fuel/air mix isn't getting into the chamber). I'm going to get one of those spring compression tools and take the intake valve out, completely clean the carbon off and reinstall it. I'm also going to put a new head gasket on. The piston appears perfectly aligned parallel to the valve opening and not worn where it seals to the opening, I just need to clean off all the carbon around the valve opening so that it closes all the way.
When the piston is halfway up the compression stroke I cannot move or rotate the valves at all.
Can I get away with not replacing the intake valve since it appears to be the carbon buildup that's the problem, or is it highly likely that the valve is damaged and I just can't see it?
Also, apparently on this model there is no intake valve seal, or it's built in somehow otherwise I would have just replaced that to be sure.
#20
R
Rivets
R
Rivets
If you pull the valve you are going to check and possibly grind it to get the proper valve clearance. If you replace the valve you will have to do this for sure. Do you know how to do this, if not don't remove the valves, just clean them on the engine and replace the head gasket. Make sure that you don't get any of that carbon between the piston and cylinder walls or you will score the cylinder walls. Don't even think about seat work.
#21
J
judge2b
You mean grind the face of the valve so it doesn't hit the other side of the chamber when the valve opens? How does the valve/rod change lengths?
I wasn't going to do anything with seat work.
I have a Tecumseh engine that I have to replace the intake valve on. It's crooked and doesn't seal when it closes. It also can be rotated while closed. Can I not just order the right valve for the engine and install it?
J
judge2b
If you pull the valve you are going to check and possibly grind it to get the proper valve clearance. If you replace the valve you will have to do this for sure. Do you know how to do this, if not don't remove the valves, just clean them on the engine and replace the head gasket. Make sure that you don't get any of that carbon between the piston and cylinder walls or you will score the cylinder walls. Don't even think about seat work.
You mean grind the face of the valve so it doesn't hit the other side of the chamber when the valve opens? How does the valve/rod change lengths?
I wasn't going to do anything with seat work.
I have a Tecumseh engine that I have to replace the intake valve on. It's crooked and doesn't seal when it closes. It also can be rotated while closed. Can I not just order the right valve for the engine and install it?
#22
R
Rivets
R
Rivets
No, if you remove the valve and clean it, you will change the valve to tappet clearance. As a valve wears, the valve stem will stretch, due to the heat. When you remove the valve and put it back in or insert a new valve, it is always recommended that you reset the valve clearance to factory specs. If you have never done this I recommend you have a repair shop do it for you. We're talking thousandths of inches. If I were you, I would take a brass wire brush and clean the valves while they are installed in the engine. Have the valve open, put a rag or paper towel in the cylinder to catch the carbon, and brush everything clean. Repeat with the second valve. Watch that you don't leave any carbon in the cylinder as I said before. Clean the top of the piston with the piston at TDC and blow everything off with compressed air to remove all carbon. It's not that hard but you must be careful.
#23
J
judge2b
J
judge2b
Oh! Yes, I was planning on resetting the clearance with feeler gauges. The tappets are adjustable on the Briggs I believe, so I don't think grinding will be necessary except in the most extreme case. I will try to just clean it the best I can without removing them and see if that works. If not, I may have to remove them, but I can reset the clearance.
I'm not sure about the Tecumseh though. The valve on there definitely needs to be replaced. If I can't set the clearance properly on the new valve myself, it just won't start and I'll have to have a professional shop adjust the valve.
If the valve does not have the proper clearance, it simply won't run, correct?
I'm not sure about the Tecumseh though. The valve on there definitely needs to be replaced. If I can't set the clearance properly on the new valve myself, it just won't start and I'll have to have a professional shop adjust the valve.
If the valve does not have the proper clearance, it simply won't run, correct?
#24
M
Mini Motors
M
Mini Motors
I just checked my B&S Service and Repair Manual, and was surprised to see that they don't publish compression ratings. But they do say to spin the motor backwards to read the compression. That may be why they seem low to some of the advisers here.
#25
R
Rivets
R
Rivets
No engine manufacturers publish compression rating anymore, due to the fact that everyone has a compression release. Those of us who say it is low, base that on years of testing and experience in doing a compression test. None of the older engines had adjustable tappets. Clearance is set by grinding valve stems, which is why I recommended taking it to a shop. Might want to check your wallet and how much you like the engine before proceeding.
#26
J
judge2b
J
judge2b
Ok. Thanks for the info. I won't pull the Briggs ones then. Not sure what I'll do with the Tecumseh yet...
#27
therev
therev
If your down that far and have the vales out. I would get some valve lapping compound (Permatex make some) and lap the valve surfaces. It will show you if there USA valve angle or seat issue plus help the valves seal.
#28
T
thstearns
Pull the plug and squirt a small shot of Starting Fluid into the cylinder. Reinstall the plug and try to start. If the engine fires and runs briefly the engine is OK mechanically and there's a problem with fuel flow--plugged float vale or somesuch. If the engine doesn't fire and run you have a problem with it mechanically--valves are not sealing or out of time, ignition timing is off.
T
thstearns
I have a Briggs and Stratton engine that won't start, model 170402, type 1015-01, code 74032510
Basically it won't start. Fuel is not getting into the engine. I pulled the plug and the valve inside opens and closes but no fuel enters the chamber when I pull start.
I have cleaned out the fuel tank, put fresh fuel in, thoroughly cleaned the fuel bowl/valve assembly, replaced the mesh filter in the bowl, replaced the bowl gasket. I also made sure air can get into the fuel tank via the small hole in the tank cap. There is no fuel filter on the line, only the filter in the bowl.
I have replaced the fuel line.
I have completely taken apart the carb and swapped out all the parts in the carb rebuild kit so all the gaskets and springs and such are new. I also thoroughly cleaned out ever single orifice in the carb. The air cleaner isn't spotless, but its decently clean and there's no gunk in any of the airways going to the carb or the engine body.
I changed the oil and replaced the spark plug. When I attempt to pull start the engine I do get consistent sparks from the plug.
I also cleaned out the breather assembly as well.
Any ideas? I've attached the parts manual as well. Some of the parts don't apply since this is one of the older models obviously.
Pull the plug and squirt a small shot of Starting Fluid into the cylinder. Reinstall the plug and try to start. If the engine fires and runs briefly the engine is OK mechanically and there's a problem with fuel flow--plugged float vale or somesuch. If the engine doesn't fire and run you have a problem with it mechanically--valves are not sealing or out of time, ignition timing is off.
#29
M
mphymel
This is my way of thinking, did it run when it was put up last season? My experience is that it is almost always (actually always!) a fuel problem.
5 for 5 on my small two strokes thanks to ethanol, and the same with my Yamaha Grizzly.
Funny story this year, I replaced the fuel pump on my Toro Z master, only to realize that the fuel tank selector was off. I had piled so much junk on the machine over the winter, something hit the selector, and since I never switch tanks, I never thought to check that!:confused2:
M
mphymel
Pull the plug and squirt a small shot of Starting Fluid into the cylinder. Reinstall the plug and try to start. If the engine fires and runs briefly the engine is OK mechanically and there's a problem with fuel flow--plugged float vale or somesuch. If the engine doesn't fire and run you have a problem with it mechanically--valves are not sealing or out of time, ignition timing is off.
This is my way of thinking, did it run when it was put up last season? My experience is that it is almost always (actually always!) a fuel problem.
5 for 5 on my small two strokes thanks to ethanol, and the same with my Yamaha Grizzly.
Funny story this year, I replaced the fuel pump on my Toro Z master, only to realize that the fuel tank selector was off. I had piled so much junk on the machine over the winter, something hit the selector, and since I never switch tanks, I never thought to check that!:confused2:
#30
B
bill1631
B
bill1631
Judge2b,
You said it was a pull start engine. A trick I use on engines that won't start is to carefully remove the pull starter and use an electric drill and socket to turn over the engine - check rotation direction before removing pull starter. Be sure and only slightly engage the socket on the shaft bolt so it doesn't come off the drill when/if the engine starts. I took a 3/8 socket extender and cut/ground off the female end so I could chuck it in my drill. I also read in an earlier post to add a little gas directly into the cylinder. Remove the spark plug, add gas, re-install the plug. This may flood the engine for a few pulls but it should fire. If not i would check the spark. If it is accessible, lightly sand the outside edge of the flywheel to remove rust on the magnet part. This will improve the spark. Good luck with it.
Bill
[
You said it was a pull start engine. A trick I use on engines that won't start is to carefully remove the pull starter and use an electric drill and socket to turn over the engine - check rotation direction before removing pull starter. Be sure and only slightly engage the socket on the shaft bolt so it doesn't come off the drill when/if the engine starts. I took a 3/8 socket extender and cut/ground off the female end so I could chuck it in my drill. I also read in an earlier post to add a little gas directly into the cylinder. Remove the spark plug, add gas, re-install the plug. This may flood the engine for a few pulls but it should fire. If not i would check the spark. If it is accessible, lightly sand the outside edge of the flywheel to remove rust on the magnet part. This will improve the spark. Good luck with it.
Bill
[