Gas generator issues

[gaugeguy]

Recently, our high temperatures have been in excess of 100 deg. and our 1975 3KW Onan (gasoline) vapor-locks after about 45 minutes of running.

The rubber fuel line enters the generator compartment at one bottom corner. Then a steel line goes over the top/back (over the exhaust pipe) of the gen. Then a rubber hose back to the floor to the fuel pump.

I re-routed the tubing and removed the steel line. Now the rubber tube comes from the fuel tank, through the floor at the opposite corner then directly to the fuel pump; thus bypassing the over-the-generator configuration.

It now runs fine even in 105 deg ambient temperatures.

NOW I have created another issue: the gasoline drains back into the tank when the generator is not in use! It takes several seconds of cranking to get the gas to the carb after sitting over night.

The generator set is well above the fuel tank and there are NO air leaks in the system.

So my basic question is: If I put a (barbed) anti-siphon valve in the line near the fuel tank am I going to experience fuel problems later because of the valve?

Sorry it is such a long-winded question, but I do need some advice.

Thanks!

[Damon Outlaw]

I guess you could go back to the original configuration and insulate the fuel line to keep the fuel cooler than before.

[IWillRVToo]

The elevated portion of the line served as an anti-siphon. You can reroute the line (again) or install the anti-siphon valve or a check valve.
I don't know of any problems you might have later.

[Tom N]

To run the fuel pump without turning the starter PUSH and HOLD the starting rocker switch to OFF for 5 or 10 seconds. This will prime the hose/carburetor. Then push the switch to start.

This procedure is in my Onan manual.

-Tom

[gaugeguy]

Thanks for the input, folks.
I have already insulated (wrapped) the tubing inside the compartment. I feel better keeping that fuel line far away from the exhaust pipe.
I believe the answer lies in the anti-siphon valve. Relatively inexpensive fix. I just wanted to make sure the valve was not going to cause a problem in the future.
Thanks again.

[Iangolf]

Something to check is the rubber fuel line attached to the top of the tank. On our 92 Allegro the genset would lose prime overnight and I traced the issue to a dry rotted fuel pick-up line. Had to drop the tank to replace however after that the issue of no fuel in the pick-up line was fixed. Just a thought.

[wa8yxm]

I started my Generator from it's "local" control switch instead of the dash remote the other day.

The ONAN manual says to push and hold till the light comes on.

I listened to the thing, when the light came on the pump started.

Then push to start.

Now I know

Push an dhold till light comes on PLUS a few seconds, then push to start.

OR:

Push Start, release (Don't lean on it)( pause, then push START again.

The paus is like 5 seconds. (you may need 10 or more, but over time you will figure the pause out)

Either method fires up the fuel pump.

[gaugeguy]

Unfortunately or fortunately our generator is equipped with a mechanical fuel pump. There are no instructions in the Onan manual other than "push start" to fire up the engine.
All the fuel lines come out of the side of the gas tank and are easily accessible. The rubber lines are all new.
We're talking 1975 technology here.
I did put an electric pump for the Dodge 360 engine (stopped that vapor lock, too)!