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Discussion Starter #1 (Edited)
I have a small 15hp tractor with a briggs and Stratton engine. After running it the other day for about 10 minutes, it started to stall out, just like it was starving for gas. I put a new fuel filter on....NG. I put a new spark plug in...NG. I cleaned the air filter.....NG. I drained the gas tank and ran the carb dry and used fresh gas...NG. It seems like it might be temperature related. As the ngine warms up, it dies out.

I'm think there is some restriction in the carb, but don't want to take it apart for nothing.

Anyone have any suggestions before I work on the carb?
 

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do a compression test on it first before you do any carb work
test cold then test right after stall out
when it stalls out how does the engine sound right before stall out
 

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Discussion Starter #3
Just before it stalls out, it sounds like it's starving for fuel. I can keep it running a bit longer if I choke it. But eventually, it dies. When it sits for a few minutes, it will restart.

I was thinking of getting come carb cleaner and just spray some of that in before i do anything further. Want to try all the easy things first.

Any other suggestions would be appreciated.
 

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wavewuver said:
I have a small 15hp tractor with a briggs and Stratton engine. After running it the other day for about 10 minutes, it started to stall out, just like it was starving for gas. ...It seems like it might be temperature related. As the ngine warms up, it dies out...
What is the engine model & type? It may have a fuel shut off solenoid located on the bottom of the carb float bowl. My Dad's 15.5 hp OHV engine quit on him (although it never would restart) and I replaced that $38 solenoid with a bowl nut & washer in order to eliminate it from ever happening again, that and it was $32 cheaper, lol.
If it does not have one of those solenoids, then I'd look at the carb. Right after it stalls, see if it'll restart, if not then I'd immediately spray some carb cleaner into it and see if it'll fire right back up. If it does, then you know the problem is fuel related. If it doesn't, then I'd check to see if it has a good spark. If has good spark (bluish in color), then I'd look into the valve lash setting as it may be too tight & not be allowing a valve to close as it expands & warms up-(a cold engine vs. hot engine compression test will help to verify this).
 

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Try it without the gas cap real quick and see if it does it again. Just to rule it out....

Usually a fuel shutoff solenoid either works or it doesn't....., and it doesn't sound like the coil right now.... being as you say it stalls, and you can keep it going longer by choking it.
 

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I have had the exact same problem with my B&s 16hp OHV engine lately....I've done all that you've done and even took the carb apart, so far no luck. I cant see it being the fuel shutoff solenoid as mine runs when you back the throttle down. I can gradually increase the throttle until a little more than halfway then it coughs and dies.
I'm pulling my hair out on this one (not much left according to the wife).....please make sure to post or email when/if you figure it out. I'm going to try to get some type of compression testing gauge Monday.
 

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SmokinGrass said:
I have had the exact same problem with my B&s 16hp OHV engine lately....I've done all that you've done and even took the carb apart, so far no luck. I cant see it being the fuel shutoff solenoid as mine runs when you back the throttle down. I can gradually increase the throttle until a little more than halfway then it coughs and dies.
I'm pulling my hair out on this one (not much left according to the wife).....please make sure to post or email when/if you figure it out. I'm going to try to get some type of compression testing gauge Monday.
Well I'd be sure that it's still getting fuel, I'd get it warmed up and then remove the air filter and try to keep it running with carb cleaner once it starts sputtering and dying when you up the throttle, if you can keep it running by spraying in the carb cleaner then you know it's fuel related, if it still dies, then it's probably spark or compression loss?
 

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Fortune50,thanks for the input. I've tried what you said and the engine chokes on the carb cleaner, backfires (sometimes) and then dies. I've tried all different scenarios....the problem seems heat related. I mowed yesterday for over an hour and with the temperature where I live around 60 degrees or a bit cooler, it ran continuos without any problem. I bet if it was around 80 that would not have been the case. :confused:
 

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Heat Soak ?

Do you have any side panels or other parts missing from the tractor? In many cases, if you take off the hood/side panels or other parts they will actually overheat because the air is not being directed in the right places.

-Larry
 

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No,no panels missing.....same issue with or without panels in place. Still waiting to hear back from "wavewuver" to see what/if anything he came up with. And I have not yet tried the compression check, probably will get a chance this Saturday.
 

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SmokinGrass said:
No,no panels missing.....same issue with or without panels in place. Still waiting to hear back from "wavewuver" to see what/if anything he came up with. And I have not yet tried the compression check, probably will get a chance this Saturday.
I'd check all the cooling air passages from the fan housing and especially on the cylinder head. Sounds like it's heating up and the valve(s) might be trying to stick. Common when it's hot. Since you said the temp was 60 when it didn't act up, that would be my first location to check. It is an OHV, I gather(?).
 

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Check and make sure the fuel tank is venting properly, if the fuel vent is plugged then it will create a vacuum in the tank and the fuel will quit flowing. After it sits awhile enough air will enter the tank to allow the fuel to flow again for a short while.

Easy test is to run unit with fuel cap slightly loose and see if this corrects the problem, also does your unit have a fuel pump?? If it does this is another area to check to see if it is working properly.
 

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I've cleaned all around the engine:cooling fins, top of the head, the base, everywhere that is visible. Is there anything that I have to take apart other than the engine cover plastic to get at? Yes, it is the 16hp OHV B&S which only recently after two years started to give me grief. To "30YearTech" : when the engine starts to act up I have taken the fuel cap off to see if proper venting may be the cause but when I did that it had no effect so after ten seconds or so I screwed it back on. I also made sure the cap vent was clean. And no, no fuel pump. Someone did mention in a previous post about the fuel shutoff solenoid possibly acting up. Does anyone know how to test it and what it should be doing when its acting properly? Thanks for any help!
 

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SmokinGrass said:
...Someone did mention in a previous post about the fuel shutoff solenoid possibly acting up. Does anyone know how to test it and what it should be doing when its acting properly? Thanks for any help!
I was able to keep my Dad's 15.5 hp B & S OHV engine running by just spraying in carb cleaner into the carb's air inlet, and it did run smoothly on the Gumout carb cleaner. To test that fuel solenoid, I used a test light on the white wire and grounded the other lead of the test light to the engine ground. The white wire lit up the test light when the key was turned on, engine didn't have to be started. The solenoid was not clicking on or off, so I assumed it was bad. If removing that solenoid and using a bowl nut in its place, I'd be sure to install an in line fuel shut-off valve when storing the mower over the winter, if the gas tank isn't drained.
If your's still won't start until it cools off, then I'd look at the valve lash settings next.
Here are some tune-up specs for the OHV engines:
Armature air gap--0.010-1.014 in.-->use a non-magnetic feeler guage (they're brass colored)
Spark plug gap--0.030 in.
Valve clearance (check only when engine is cold):
Intake valve lash--0.003-0.005 in.
Exhaust valve lash--0.005-0.007 in.

From the B & S website (slightly edited for easier reading):
"Adjusting Overhead Valves

Note that this procedure is performed on a 6 hp Intek OHV engine.
Release the brake spring (if equipped). Then remove the valve cover. Now turn the flywheel until both valves are closed.

Insert a narrow screwdriver into the spark plug hole and touch the piston. Turn the flywheel clockwise past top dead center until the piston has moved down 1/4". Use the screwdriver to gauge the piston's range of motion (image F below). PLEASE NOTE: This procedure must be performed for each cylinder on V-Twin engines.


Remove the valve cover.

Check the valve clearance by placing a feeler gauge between the valve head and the rocker arm (see image G below).

Adjust the clearances as required by turning the rocker screw. Once adjustments are completed, tighten the rocker nut.

Install the valve cover, using new gaskets, as required, and make sure the cover is secure."
Hope this helps to narrow it down. :cool:
 

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To test the solenoid, pinch off the fuel line so fuel will not flow. Remove the solenoid, with the solenoid pluged in ground the solenoid to the engine block and turn the key to the on position -- observe the needle it should move down into the solenoid housing and raise when power is discontinued.

The fuel shut off solenoid is there to help prevent after burn in the muffler when you shut down a hot engine (you know the bang some bigger engines make when you shut them off). It prevents alot of unburned gas from getting sucked through the engine and collecting in the hot muffler when you shut an engine off. You can replace it with just a bowl nut or if you don't care about the soleoid you can just cut the needle off and leave it unplugged. You may get a bang when you shut down the engine without it though.

I think you may have some restriction in the carburetor, maybe the inlet metering needle or something getting drawn up into the main jet possibly a little water rolling around in the float bowl. Something is causing the mixture to lean out and I suspect it has something to do with your carburetor.

Ken
 

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Ken, one of the things I did last Saturday was to remove the carb and clean it. It was in perfect shape,like brand new. I did use carb cleaner and compressed air to blow all the ports and jets though and when reassembled, the mower ran like clockwork for ten minutes then sputtered surged and died. There's something to be said about the fact that when it gets to this point, it surges then fades like it's going to die the surges,etc., and repeats this over and over.But if I back down the throttle all the way it will run nonstop.Its when I up the throttle, around halfway or 3/4 up it goes into its stalling mode again. I'm an electrician, not an engine mechanic, so for me this is a real head scratcher....I have a chance to go out today to work on it so I'll keep you all posted and thanks for all the info! :confused:
 

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Another thought, maybe a small air leak in or around the intake manifold, could get worse when engine heats up. To check this, take the shroud off and with the engine running spray carburetor cleaner around the mtg points of the manifold, if the engine runs rich or dies when you do this, it indicates a leaking gasket or seal etc...
 

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Discussion Starter #19
Turns out that the carb needed a good cleaning. There was some rust in the bowl. That's what the shop told me.

Thanks for all of your suggestions.......
 

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That's great....I wish my problem was that easy. But I can't complain, I've mowed the lawn twice now without incident, I'm keeping my fingers crossed. I'll keep you all posted, many many thanks so far for all the advice thats been given.
 
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