Onan 5500 EFI Generator pumping gas out of Carbon Canister

[larrywwiley]

Installed Onan 5500 EFI Generator in Cyclone 4100 King HD. Used Heartland factory installed fuel and vapor return lines. Intake line runs from fuel tank through an auxiliary pump to supply fuel to the generator and the other is the return line which attaches to the carbon canister at the fuel tank. the return line is attached to the generator vapor port (b) on the carbon canister. When the generator runs, gas is pumped out of the large (air) outlet on the carbon canister.

Here is what I suspect:

The return line is installed to return fuel vapors from a "Carbureted" generator, not a "Fuel Injected"one to the carbon canister. For a fuel injected system, the return line should be used to return excess unused fuel back to the supply tank, not fuel vapors as in a carbureted system. As a result, the return line should be connected to the supply tank and not to the carbon canister.

I see no need for any connection to the carbon canister since there are no fuel vapors in a fuel injected system as there is in a carbureted system. The only connections at the generator are for the fuel supply and fuel return lines. There is no connection for a Vapor return.

Please let me know if I am right and if so, how and where to connect the return line to the supply tank. If I am wrong, please help me to the right setup.

Thanks,
Larry Wiley

 

[danemayer]

Hi Larry,

Welcome to the Heartland Owners Forum. We've some people here who are very knowledgeable about those generators so I expect you'll hear from some of them shortly.

 

[porthole]

Canister is for vapors only.

If you have a fuel injected gen that has a supply and return line, then you are correct, you need to run the return line from the fuel injection pump, and just not use the vapor canister.

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Is that vapor canister attached to the tank? If so it may very well be for the tank venting purposes.
Do you actually have a return port on the tank?