ltoolio

Just finished reinstalling my fuel tank and want to test for leaks by jumpering the fuel pump relay.

Any best practice as to how long I should run it?

*Edit* - Also, how long should I expect there to be fuel coming back from the return line?

soontobered84

Long enough to look at each injector connection, each connection under the hood, and also long enough to get under the rear of the car and ferret out anything leaking in the fuel pump area or anywhere else that you have messed with the fuel line connections. The fuel system is going to return the unused fuel back to the tank if the system is working properly.

ltoolio

Thanks, John.

I have not touched anything at the front end (not to say I still won't check) so will jumper, monitor the rear and hopefully walk away with everything dry.

ltoolio

Hmmmm.

So. Ran the FP jumpered for around 10 minutes. I could hear the FP working, could hear some gurgling from the tank and heard some fluid movement in the engine compartment.

However, I'm not getting anything coming back in the return line. I currently have it draining to a container to test if I'm getting flow (I had a blockage in the return hard line as detailed here), and assumed I'd see some trickle outward.

But....nothing.

Could it be that things have just not fully filled upstream enough yet? Should I give it more time? Investigate the return line further upstream? Light a match to the gas fumes and call it a day?

GT6ixer

Haha, don't do that last thing. I think you should get fuel returned almost immediately (under a minute for sure), at least it was when I did it a couple week ago. 10 minutes is a long time to have it jumpered IMO. Did you verify that you have fuel coming through the supply line? There is a WSM procedure to measure the volume in a given amount of time. Can't remember offhand the metrics. If you are getting supply flow then something is blocking the flow upstream of the return line exit. When you cut the hard line where the rust was at were you able to then blow air through it in both directions?

ltoolio

Thanks, Nate.

Things were clear at the point where I cut the return line, so it was good at least where I made the trim.

I'll read up in the WSM on the fuel volume, but it sure sounds like fuel is making it up to the engine.

I was thinking about connecting an external power line to the FP just to make sure it's pumping in the right direction. I have the terminals properly connected via their size difference, but it's possible that I reversed the wires when I cleaned up the original splicing.

GT6ixer

Found it.

ltoolio

Thanks again, Nate.

So...I don't have ready access to the return line due to my SC, and since I don't have the time window currently to go that route, I hooked up an external PS to the pump.

Regardless of which way I have the terminals connected, I have no fuel coming out of the return line (towards the rear of the car, where it connects to the soft line).

When I had them reversed, or at least I think was reversed, I was getting an odd rhythmic sound coming from the front:

Mrmerlin

did you replace the fuel dampers and fuel pressure regulator?
if so then you probably have the FPR at the front center and the damper at the RR fuel rail

ltoolio

Negative. I have not touched anything in the engine bay. Everything I have done has been at the tank end.

Mrmerlin

get a test light and see if the hot post of the fuel pump will light the lamp,
the other end is grounded maybe crossed wires?
a pinched line from jacking?

ltoolio

As is typically the case with me, it was user error. Terminals were screwed up. Thanks as always for the input.