Generator Running out of Gas

[turbojimmy]

This is on my 30-year-old Onan 6.5. Once a month I exercise the generator, once a month it will run for about 30 seconds until it's out of gas. If I dip the fuel line into a gas can, it will run fine. Then I hook it back up to the stock fuel feed and it will run for hours no problem.

The rubber fuel lines are new.

The only clue, maybe, is that when the fuel pump is running dry it gets loud. When I dip the line in a gas can it quiets right down. When I hook it back up to the stock line it gets loud again but continues to run. This time around I blew the line out with compressed air but it didn't seem to help.

Weak pump? I'm not sure what to think. Filter is new.

[jwmII]

After 30 years if there is any of the old rubber line from the tank still in service it is probably pulling air thru dry and hardened and cracked hose. This assumes the gas tank has enough gas in it for the Onan fuel pump to pick it up. It also assumes the filter in the pump along with any other filters that may or may not be in the line are clean.

[Big_Katuna]

You said new rubber line. Is the line going all the way to the big tank new? Sounds like it might be sucking some air somewhere if pump is still straining.

[midnightsadie]

then its real possible the fuel line is collapsing do to a clogged vent. it runs if you prime it , its in the fuel delivery part of your set up .

[turbojimmy]

That's what's perplexing. I can get it going with the gas can, then hook it back up to the main gas tank and it continues to run. I thought maybe it was below 1/4, too, but it continues to run so long as I "prime" it with a gas can. It's still out there running since my first post, actually 🙂

[rgatijnet1]

You have an air leak somewhere in the line or the tank is not vented and you are creating a vacuum. .

[midnightsadie]

if it runs off your main fuel tank?? you have to have MORE than a quarter tank of fuel or the genny won,t pick it up. safety feature.

[sljkansas]

If your pulls from the fuel tank of the rv, and youe tank is Under 1/4 a tank that me be you problem. My old class C was setup that way.

[Sully2]

I think a Cummins / Onan tech should take a good long look at it!