FUELING ISSUE - FUEL FILTER

[greenohawk69]

I have removed the vacuum petcock, installed new fuel line (not fuel injected hose) and a quick disconnect from the tank and before the fuel filter.

Bike has been run 3-4 times and each time it dies from no fuel. The tank has been full and 1-2 gallons.

Have disconnected fuel line from fuel filter (quick diconnect connected) and fuel flowed through.

Replaced fuel filter again as there was sediment.

Fuel line was disconnected after the shut off valve also and fuel flowed through.

The fuel starvation issue is noticable at the fuel filter as it can be empty to barely any fuel in it. The bike has sat overnight and the fuel filter is filled with gas. I'm using a Duralast FF3407 part.

Could this issue be caused by the removal of the vacuum petcock? Bike did sit previously for ~ 1.5 years, but ran fine. Have also used the Duralast FF previously.

Picture is attached of current setup w/o vacuum petcock.

[ducpainter]

It has to be a vent issue.

Remove the little rubber piece under the fuel cap. It's only used for the vapor canister, and will eliminate vent hose pinching. If it still has an issue it would be internal in the cap.

[greenohawk69]

Thanks. I will check that also.

[ducpainter]

Thanks. I will check that also.

If that doesn't work...you mentioned sediment in the filter. If the tank indeed had a build up of loose sediment, it's remotely possible that the fuel outlet from the tank is blocked and is impeding the flow...I want to emphasize the word remotely.

[greenohawk69]

I thought that might be an issue too and ran a hose through the tank yesterday and drained it. Flow out appeared to be ok. Flow appeared ok with gas when I drained and filted into gas cans. Will also filter gas from can to tank. And a new a filter was installed.

[Blackout]

Hate it when my flow is interrupted.
My Triumph had a similar issue but it was just due to a loose fuel pump relay.

[ducpainter]

Carby Monsters really don't require all that much flow.

I'm betting that rubber piece under the cap is distorted and blocking the vent hole in the cap, the vent hose under the tank is pinched, or the steel tube inside the tank is blocked.

Removing the rubber piece solves all three issues.

[greenohawk69]

It appears I solved this issue. I flipped the FF 180* so the gas flows via gravity and not upwards like the stock location.

[ducpainter]

My fuel filter is in the stock location and it seems to work fine.

Something is going on.

[greenohawk69]

Have you run the gas tank low and experienced any issues? Has the fuel range on the tank the same with and without the vacuum petcock?

[greenohawk69]

Would I be able to snake the in/out vents underneath the tank for blockage (e.g. using stiff wire)?

[ducpainter]

Have you run the gas tank low and experienced any issues? Has the fuel range on the tank the same with and without the vacuum petcock?

I've gone 150 miles on a tank with no issues. The most I'd gone before was 160ish.

Would I be able to snake the in/out vents underneath the tank for blockage (e.g. using stiff wire)?

Try it from the top. Did you remove that rubber piece from under the cap? That is the vent line. If the rubber piece is gone the vent tube amounts to squat. The one on the side that you can't really see unless you remove the cap is the drain.

[greenohawk69]

Yes, the rubber piece under the cap was removed.

[greenohawk69]

I think I used the wrong term. The overflow tubes/vents underneath the tank - with the rubber hose attached.

[ducpainter]

I understood what you meant. My point is that if the rubber piece has been removed, and you're still not flowing fuel, either the cap is defective, or you have a flow restriction. Snaking the tubes in the tank won't help.

Try running the bike with the cap open.