At 1/2 tank it stops running

[ABC]

Hey Russ,
You know that my pw can balance a quarter on it's side. You helped me get it there with the right gear.

What I can't figure out is why it stops running at 1/2 tank full of fuel. About 2 hours run time.
Runs perfect, no problems other than that. Top it off and it's fine for 2 more hours.

I usually can get almost 4 hrs out of a tank of fuel.

Any clues?? It has been pm'd to the hilt. Just thyis one issue.

The tank is on a briggs vtwin on top.

 

[Russ Johnson]

Next time it stops, loosen the gas cap and see if it'll run. Could be a clogged vent.

 

[scottwash]

Same thing happend to me and went back to a old gas cap and fix it. This was on a new honda 13. But I have gotten that info off PWI. Thanks
I was thinking that the cap is not vented enough for the gas to flow to the carb.

 

[K.J.]

Had the same problem with my back up 13 hp Honda...eventually went back to the older style gas cap and all is well again.

 

[Doug Rucker]

Same here...went back to old gas cap. But Adrian yours should have the old gas cap. Mine is fairly new

 

[offdutyfireman]

The new caps have charcoal in them. If they get wet with gas they can't vent.

 

[Doug Rucker]

Here are a couple pics. The big cap is the one the machine came with. The small one is the one I relplaced it with. The repair guy here told me Honda actually had a recall on these big caps.

 

[JBurd]

That's helpful to know I have the better caps. My gx390 had been shutting off and I think my problem might be that when its not perfectly level the oil flows away from the low oil shutoff sensor. I add a little engine oil or level the machine and it works.