return fuel line location

[Dargo]

Greetings all, I am the proud owner of a 1974 FJ40 for over 40 years. Was doing some fuel and vapor line replacement and I found that the fuel return line was capped off. Any ideas of where it goes to fromm the tank? Thanks, Dargo

 

[Capriblue45]

your fuel pump should have 3 connection to it, it will go to the one nearest the inlet hose from the tank. There should also be another hard line on the frame rail next to the supply line from the tank. If it has been disconnected you should remove and flush with some brake cleaner and compressed air to make sure you do not damage the pump.

 

[Dargo]

Thanks Capriblue45, I appreciate your response. I will do that. Looks like I need to drain the oil and take off the oil filter bracket to access the fuel pump inlet. Also, should I replace the charcoal canister as well? Thanks again Capriblue45!

 

[Capriblue45]

You should not have to do that to access the ports on the fuel pump. Is yours a 2F or a 3.9l f engine? pump should look something like the photo. The port on the right side with the extra hose on it is the return. Picture taken from the front of the truck.

 

[Capriblue45]

As for the charcoal canister I am not sure where you might be able to find one of them for your truck. They do have a tendency to breakdown over time and plug up.

 

[Rzeppa]

You should not have to do that to access the ports on the fuel pump. Is yours a 2F or a 3.9l f engine? pump should look something like the photo. The port on the right side with the extra hose on it is the return. Picture taken from the front of the truck.

A stock 1974 was a transition year. It was the last year of the F engine, but the oil galleys are routed internally same as a 2F. It uses the block mounted oil filter near the fuel pump and distributor rather than the remote oil filter mounted to the manifold of earlier F engines. The fuel pumps of these earlier motors only have an inlet and an outlet and no return like you see on later 2Fs. That line should stay capped off. From memory, they started using a return line to the pump ~79 or so? I know my 76 and 78 do not have returns on the pump.

 

[Capriblue45]

Thanks for the clarification on this Jeff, I could not remember if the 2F started in 74 or 75.

 

[Rzeppa]

Thanks Capriblue45, I appreciate your response. I will do that. Looks like I need to drain the oil and take off the oil filter bracket to access the fuel pump inlet. Also, should I replace the charcoal canister as well? Thanks again Capriblue45!

You don't need to drain the oil to take the filter bracket off, the oil will stay in the pan when the motor isn't running. You'll just get some dribbles from whatever is left in the filter. Charcoal canisters normally last forever unless they've been saturated due to a fault. The check valve barbs can get brittle and break when they're real old though.

 

[Dargo]

Thank you all your info! Yes it is an F engine and the fuel pump does have an opening facing the firewall. So I will leave it as it is, return line blocked. My apologies for another question, that three chamber fuel separator, is that something I should also replace do you think?

 

[Dargo]

Thank you all your info! Yes it is an F engine and the fuel pump does have an opening facing the firewall. So I will leave it as it is, return line blocked. My apologies for another question, that three chamber fuel separator, is that something I should also replace do you think?

Fuel cap vented or not?