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tractor shuts down after 25 minutes and difficult to restart

#1

J

jneknez

Hi all,
I have a 20hp B&S engine. Brought it to the local repair shop because the battery would be drained after 5-6 weeks. They tested and said there was nothing wrong with the charging unit despite the fact that I am now on my third new battery.
They put a new fuel filter and air filter and I replaced the plug. It starts up fine and will run perfect for about 25 minutes then shuts down. It will crank but not restart. After letting it sit for 5-10 minutes it will restart and run for two or three minutes then it will shut down again. This condition repeats over and over. It has happened several times and can be reproduced.
If it sits for a while and cools down it will run perfect again for 20-25 minutes before the same symptoms appear.
I tested for fuel and spark when this happens and I have both. Was thinking it was the coil but since I have spark I doubt it.
Planning to bring it back to the shop but was hoping for some help here.
Any thoughts would be appreciated.
Thanks.
-Jason


#2

I

ILENGINE

Re: tractor shuts down after 25 minutes amd difficult to restart

Next time it quits, turn the key off and back on a few times, and listen for the fuel solenoid clicking on and off, down at the carb. Possible that the fuel solenoid is cutting out when hot. I have also seen the pulse fuel pump cut out when warm also.


#3

J

jneknez

I should hear it by turning the key but not trying to crank it?
Thanks.


#4

I

ILENGINE

That is correct.


#5

J

jneknez

Same condition again today. I listened and can hear the fuel solenoid clicking. There is Ana assist that help the fuel pump? The manual is useless. I figured it was just gravity fed from the fuel tank. It does feel like it is a fuel issue though. Today when it was about to quit on me I immediately moved the throttle to choke and it continued running.
Any other thoughts?
Thanks.


#6

I

ILENGINE

Sounds like fuel problem. Does it have a fuel pump. If so check the vacuum line for cracks. I have seen the vacuum fuel pumps on briggs quit when they get hot. When it quit remove the line going to the carb, and have somebody crank the engine while collecting the fuel to check that the pump is working. if no fuel pump remove the fuel line from the carb, and let the fuel flow into a container, paying attention to how much fuel is flowing. Meaning is it flowing with a full line or just running slow.

If this is a newer mower, feel the fuel lines for sponginess. The newer low permiation fuel lines will have the inner liner separate from the rubber fuel line and will restrict flow.


#7

S

SeniorCitizen

Have you tried loosening the gas cap?


#8

reynoldston

reynoldston

Check your fuel tank vent.


#9

M

motoman

There are fuel delivery amounts specified for cars in the scenario by IL ENG; e.g., so many cc's (or ozs) when cranking for so much time is expected etc. Any such for these little engines?


#10

I

ILENGINE

I was thinking there was, but according to the fuel pump testing service bulletin, it just says if when cranking flow is steady pump is good. If low volume or erratic then further testing is needed, which requires a vacuum/pressure tester.


#11

J

jneknez

I have tried loosening the cap, completely removing and cleaning the vent hole. I don't think there is a pump. The fuel line runs from the bottom of the tank into the filter then into the carb.
I will try cranking and seeing how much fuel is coming through the line then try it again when I have this condition. I'd be surprised if it was different though.
Thanks for the ideas.


#12

I

ILENGINE

I went back on read your original post and noticed that they installed a new fuel filter. Which fuel filter did they install. There has been cases where the fuel filter for a fuel pump system was used on a gravity system, and would restrict flow and cause running problems.


#13

J

jneknez

They said they installed OEM parts the bill says RT 1358 1/4-5/16 filter. I thought of buying another and replacing just to rule it out but it would be odd behavior for it to run properly for nearly a half hour then cut out don't you think? This problem is very consistent now each time I run it...then it runs smooth again once it sits a while. I've also adjusted the mixture slightly in both directions with no change.


#14

I

ILENGINE

That part number is for a Rotary aftermarket fuel filter. it crosses over to the 25 050 22-s Kohler filter which is 51 micron designed for fuel pump use only. So there may be something to the fuel filter. I would try a different filter designed for gravity flow systems. Something in the 75 micron size range.


#15

J

jneknez

Thanks for checking...I think that has to be my next step. I will pick one up in the morning and run it again.


#16

B

bertsmobile1

Befire you start mowing remove the fuel line and time how long it takes to to fill a cup.
When it stops new time measure how long it takes to fill the same cup.
If there is a significant difference then remove the fuel tank & clean it out.
Check the outtlet hole carefully as some times a flash of plactic from the moulding partially blocks the outlet and other times the outlet hole is not quite big enough.
Then you add debris sitting on the bottom of the tank that iss too big to flow down the line & you can get this exact situation.


#17

J

jneknez

Thanks to everyone who offered advice. I finally have it figured out. Ran it again today. Timed the fuel flow while cold then the same issue presented at the same time as previously noted while running. As soon as I felt the slight hesitation again I put it in full choke and was able to run a few minutes longer. When it finally died I pulled the line from the carb and there was a trickle for 4-5 seconds then the trapped air in the filter cleared and it started flowing freely again. I reconnected to carb and it started right up. The suggested 33940 fuel filter appears to be discontinued and Sears only sells 33392 locally. I have it but am hesitant to throw it on. Looks exactly like the new one the shop installed.
My final concern is that the line coming from the bottom of the tank goes slightly uphill to rest on a bracket on the tractor then down to the filter and again slightly uphill into the carb. This has been the same flow since purchased new 6 years ago and never a problem. I'm going to shorten this line so it is a bit more direct.
Thanks again for your thoughts and assistance.


#18

B

bertsmobile1

jneknez said:
Thanks to everyone who offered advice. I finally have it figured out. Ran it again today. Timed the fuel flow while cold then the same issue presented at the same time as previously noted while running. As soon as I felt the slight hesitation again I put it in full choke and was able to run a few minutes longer. When it finally died I pulled the line from the carb and there was a trickle for 4-5 seconds then the trapped air in the filter cleared and it started flowing freely again. I reconnected to carb and it started right up. The suggested 33940 fuel filter appears to be discontinued and Sears only sells 33392 locally. I have it but am hesitant to throw it on. Looks exactly like the new one the shop installed.
My final concern is that the line coming from the bottom of the tank goes slightly uphill to rest on a bracket on the tractor then down to the filter and again slightly uphill into the carb. This has been the same flow since purchased new 6 years ago and never a problem. I'm going to shorten this line so it is a bit more direct.
Thanks again for your thoughts and assistance.
Click to expand...
Blowing the line out to make sure it is clean is a good idea, shortening it is not. It needs some wriggle room and a fuel pump will overcome any up hills.
Pull the line to the carb off and the plug out.
Earth the plugs as far away as possible put the carb line in a reasonably bigjar with some fuel in the bottom like you are about to bleed the brakes.
crank the engine and watch what comes out.
You should get a little air at first then it should flow free & clean.
If you are geting a lot of air then the pump is sucking air & you have a hole, bad diaphragm, loose joint,


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