How to prevent generator vapor lock

Trace fuel line to make sure it is not running close to and parallel to rigs exhaust.
Look at fuel line to make sure it is not sucking air. Between tank and fuel pump.
Test or replace fuel pump
Make sure you are well over 1/4 rank of gas.

Avoid gas mixed with alcohol. Antique car guys add kerosene or some diesel but it also lowers the octane so I would not do that to the motorhome motor.

Another thought is I wonder if maybe the feed line to the electric fuel pump is collapsing from age. The warmer it is; the easier it collapses.

Also inspect the routing to make sure it isn't near a heat source like the exhaust.

what about some sort of insulating tape on the fuel line?? would something like that possibly help??

I'm sorry that I can't help, but we haven't had any problems with ours yet which is the same generator. Used it for three days at the hydro plane races last year where it stayed well over 100F all of the time and the last day was 105F. We've run ours both stationary and going down the road.

When it gets the vapor lock, what does it do? Does it overheat and shut down, does it starve for fuel, or?

Will be interesting to see if others have had the problem and their solution.

Bill

could be your letting the fuel tank get to low, and its seeing low fuel and just shuting down ,at a 1/4 tank.

If you're sure it's Vapor Lock (liquid gasoline evaporating to vapor in the fuel line/filter), then have you inspected the routing of the fuel line? It may be near a hot spot. Exhaust, for example, of the road engine or the genny itself.

Are you sure the genny's fuel pump isn't weak? If it persists, I suppose you could mount another pump, near the main fuel tank, and let it have a very short "pull" from the tank then it would "push" the fuel toward the genny. This is part of the logic behind putting the fuel pump IN the tank. With the fuel being PUSHED all the way from Tank to Engine, very little chance for it to go to vapor.

Just be sure that if you add another electric pump, that it works off of whatever safety feature that stops the OEM pump if the genny stops. You can determine that from the wiring diagram in the service manual, or probably just tie it to the power for the OEM pump. Might need a bigger fuse..

kmb1966 wrote:
I have a Onan Gold 7000 generator. Runs fine normally, but sometimes when traveling in hot weather it develops vapor lock. When it happens, it has been when temperatures outside are above 97/98. We hate to travel when it is that hot, but sometimes crossing Texas in June/July, it's unavoidable. When it's that hot it is also a time that you really need the a/c working well, and if the generator develops vapor lock, then no a/c and it's a miserable situation. I'd like some ideas on how to avoid this situation for this upcoming summer. Thanks.

Onan is installed in a Itasca Suncruiser Motorhome

What was the outcome?

Bill

More ventilation for the fuel pump and the fuel line going to the pump.
If this is a recent problem it could be a weak fuel pump.

There are several conditions mistaken for "Vapor Lock" Classic vapor lock is when the gasoline in the fuel pump vaporises so the pump is pushing gas. not liquid, since gas compresses easily it can not supply the engine with enough fuel.

This should not happen once it has started as the flow of FRESH gasoline from the tank will keep it pumping liquid.

One solution is to Choke the thing breifly on start up but.. Well, to be honest this should not be necessary on the ONAN since they use a fuel pump that is .. Resistant to Vapor Lock.

So are you sure it's vapor lock?

Did the original poster resolve this issue? I have been keeping a close eye on this issue and it appears that this issue is more prevalent that one would imagine. Possibly all heat related. One suggestion I have heard is to move the fuel pump out and away from the generator enclosure. Do we have an update on this?