Glen McCartney

Today, decided to replace fuel filter, short hose from tank to fuel pump and put in a new check valve. Simple, right?

Well, all done, go to fire up car, fuel pump is whirring nicely, no fuel leaks, but only about 18PSI and car won't start.

Everything was fine before I started this simple project, fuel pressure was around 40PSI.

Possible that the strainer got clogged when I drained the tank? Collapsed the strainer when tried to restart? Any other ideas?

Going to put in a new strainer, wish me luck that the old one comes out easy without messing up the tank.

SharkSkin

Route the short hose between the tank and pump to a container with fuel in it and see if that improves your pressure. If not, don't mess with the strainer -- sometimes the threaded bung in the tank comes loose when you try to remove the strainer. Better to not touch it unless you know it's necessary.

Glen McCartney

Dave, good idea, will try that first. I wonder if the fuel pump is weak and the new check valve is causing that to show up, not enough umph from the old pump.

ZEUS+

Try Daves idea, that will help isolate problem. The check valve only comes into play on shutdown. Its purpose is to hold fuel in lines and rail for startup. It's also possible that something got into fuel line causing regulator to be open or regulator failed. You can clamp off return line and see if pressure increases.

G Man

I have never done this job so I do not speak from experience. Is there any possibility the check valve could have been installed backwards?

Mike Frye

I was just going to say the same thing. That would mean it would ONLY allow the fuel to drain back into the tank.

RicerSchnitzzle

Did you disconnect the eletrical to the pump? If you hooked the wired up backwards you will get very low to no pressure, as the pump is now spinning backwards...

SharkSkin

The check valve cannot be installed backwards, there is a non-threaded portion that would prevent that:



OTOH, reversed leads are possible, but wouldn't that pump fuel back into the tank?

Mrmerlin

if you look carefully at the pump you will see a PLUS and a MINUS nest to eash wire connection, dont over thighten the nuts you can snap off the studs

Mike Frye

Dave, seriously. Do you have a picture of every single part of the car in your archive?

Bill Ball

Also, the wire ends are keyed (different sizes). On the external pump, the posts are different sizes. On the internal pump, the spades are different sizes. Hard to get the polarity backwards.

SharkSkin

Not quite... I'm getting there though.

Glen McCartney

Haven't had a chance to troubleshoot today. The check valve can really only go in one way with feed holed inside banjo fitting. Bill is correct, the + terminal has a smaller hole/stud than the - terminal, so can't wire backwards unless on purpose. Hopefully work doesn't get in the way tomorrow so I can try a couple of different things.

RicerSchnitzzle

OR someone replaced the wire ends in teh past like on mine...

Bill Ball

Nasty. Eh, double check the leads with a meter.