Onan Emerald 1 fuel problem

[Coastal11]

Hi All,

Just went to do my oil on genny  to find that the sump is full of petrol now it was not like that last month, in one word HELP!!!!!
I was wondering if the outside day time temp of 45 deg C could of had any bearing, I am open to ideas please.

[Rickf1985]

I am wondering if fuel is siphoning from your tank past the pump and into carb. If you have a leaky float needle it will keep dumping gas into the engine through the carb and past the rings. You may want to rebuild the carb or at least get a new needle and seat.

[DRMousseau]

OMG!!! 45degrees C.!?!? That's like 114degrees F.!!!! WOW!!! THAT is HOT!!!!

Is there a release of pressure when you remove any fuel tank caps??? Most fuel systems are vented to release pressure caused by high temps. But if these systems are faulty, plugged, or obstructed,... high temps like this can cause excessive fuel tank pressure. This can cause fuel to flow past float seats, leak thru poor fuel line connections, and even damage fuel pump diaphragms!!!

MAKE SURE there's not any excessive pressure in your fuel tanks on hot days!!!

[Rickf1985]

That is a good point. That vehicle will have a vapor canister emissions system which recovers vapor from the gas tank and the carburetor when not running and stores the vapor in activated charcoal canisters, two in your case. Once the vehicle is started the vapor is drawn into the air cleaner to be burned. If the vent line from the tank to the emissions canisters is plugged you could very well be building up a lot of pressure in the tank and causing exactly the problem you are seeing. There will be a label on the side of the air cleaner that shows all of the vacuum lines related to the emissions system. I don't remember if it shows the vapor recovery lines or not. If not they should be in the service manual on here. I am headed to bed or I would look it up. I used to know all those lines but it has been a while since I regularly worked on those systems.