Repairs tractor shuts down after 25 minutes and difficult to restart

[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

 

[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.

 

[jneknez]

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

 

[ILENGINE]

That is correct.

 

[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.

 

[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.

 

[SeniorCitizen]

Have you tried loosening the gas cap?

 

[reynoldston]

Check your fuel tank vent.

 

[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?

 

[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.