Generator fuel pump not pumping

[mkirsch]

We got socked with 81MPH winds yesterday which knocked out power, so I'm using my camping generator to keep the fridge cold and the house warm. I'm still running that CaseIH (aka PowerEase and others, Chinese) 3500W generator that I've talked about on here before.

I've been having this problem where it runs for 30-60 minutes, then starts sputtering. It will run a little longer if I choke it, but it quits after another minute or so.

Last fall I replaced the fuel pump with a genuine Honda part (identical to the eu2000i pump), thinking that was the problem. No change.

It runs like a top when I hook my test tank to the carburetor directly and gravity feed it. I ran it for 2 hours this morning off the test tank with the refrigerator and furnace, and it didn't miss a beat.

With the pumped fuel line disconnected and the engine running off the test tank, it isn't pumping much fuel at all. Barely a dribble. When I suck/blow on the impulse line, fuel SHOOTS out the line so I know the pump is fine.

I have poked a wire into the impulse port on the engine, and saw it come out in the intake port on the head. The hole is clear.

Any ideas why the engine won't pump fuel? Again, it runs like a top when gravity fed from the test tank.

[MrWizard]

Assuming you are starting with a full tank
What happens if you start cold with the left over fuel in the external tank
Could be a lift problem
Just for testing
Try running it with the cap loose or off
Maybe it doesn't vent as well as it should and it's over working the pump
Check ALL lines and fittings an air leak in the fuel line or a vacuum leak driving the pump, can cause issues like this

[mkirsch]

Both tanks are vented.

You would think if it was a tank venting issue, that it would go away immediately as soon as I opened the cap on the tank. It doesn't.

Once the generator starts stumbling on the pumped tank, it is just a matter of a couple minutes before it quits entirely, even with the cap off.

As soon as I attach the test tank it runs fine.

[MrWizard]

Two things, I can think of
Is the aux tank vented? It must let air in or you create a vacuum inside the tank/can and then the gas can't flow

Or maybe a vacuum leak after the engine warms up

[mkirsch]

Nope. Fuel filter is new too.

As I said, if I suck/blow on the impulse line to the fuel pump, fuel SHOOTS out. if the filter was plugged, it wouldn't SHOOT like that.

[John_Joey]

Is there a fuel filter that is being overlooked?

[mkirsch]

The generator does have provisions for 12V but it is missing the circuitry to rectify and regulate it. That was the dangling blue wires I found inside the generator that I asked about here a couple months ago.

[j-d]

Does the genny produce 12-VDC to recharge its starting battery? If so, I'd consider an electric pump, along these lines
The common pressure is 5-7 PSI but there's also a "low pressure" version (3-5 if I remember) version, that I used for the ONAN on a coach. You'd need a Primer Button switch to fill the carburetor before you start the genny, if it's been standing awhile.