Found where fuel pressure is going, return line. now questions.

[jeff89fbird]

Is the return line affected by the regulator?

I guess I wasn't pinching it off good enough before. Anyway, the pressure holds steady now when I pinch off the return line. So somewhere

Now from what I understand, if the regulator is bad, the fuel would be coming out of the small vacuum hose, and nothing more. Or am I wrong?

Is there something at the fuel pump that controls the return line, or is it controled at the fuel rail?

If the regulator is what's letting fuel through the return line, then could I use a 3.4 regulator to replace it for now? I still have that with all my 3.4 parts.

[Doubt_Incarnate]

you could probably use it. a regulator can fail a number of ways, the diaphram could rupture and fuel can leak thru a vaccum line, or the spring can fail and let more fuel flo thru the return line and reduce the pressure on the rail/injectors. you seem to be getting the latter.

the return just does what its named for, returns un-used fuel to the tank. the regulator is just a controlled obstruction to allow the fuel to build pressure for injection. the regulator is designed to hold enough fuel back for this purpose, the rest is allowed back to the tank, if it held all the fuel back the injection pressure would be too high and too much fuel would be used.

[jeff89fbird]

Ok, I pulled the regulator off and I see now. I replaced that regulator only a few years ago and it looks new still, but who knows. I'll go check again for anyway it might have been leaking past it.

The 3.4 regulator looks to be in okay shape too. I think I'll go put in on and see what happens.

[jeff89fbird]

put the 3.4 regulator in and it still loses pressure. Squeezing the line doesn't even stop it now. In the time it takes me to turn the key off after it primes and get around to the gauge it's down to 20 and once I get the visegrips or pliers onto one of the lines it's at about 15.

I finally lost my temper and now have a new ding in my fender. The fender that will get some bondo or be replaced anyway when the POS get a paintjob.

I'll fight with it again tomorrow night I guess.

[SappySE107]

Fuel pump has a check ball in it on the return side I would imagine. What is the running pressure?

[jeff89fbird]

30, last time I had it running a few days ago. I"m going to pull the return line off and see if its coming out while the pressure is dropping.

[jeff89fbird]

Well, pinching the return line caused it to stop again. Next try it didn't so I bent the hose slightly at the pliers and it stopped again. Resumed leaking when I released it.

The regulator springs have a lot of tension in them (2.8 and 3.4) and the surfaces look good. I can't see any imperpections in the rail where the regulator center thing seals.

(both springs bad maybe, even then I'd think it would stop at a certain pressure, this just goes right down to zero.)