I just swapped in a new intake rig, injectors, PROM, etc. Car ran fine when I shut it down before the upgrade. My problem: No Fuel pressure. The pump primes as normal (scanner shows voltage) , no leaks anywhere, adjusting FPR does no good, lines are hooked up correctly (can't mess that up), and I get (barely) 8 pounds at the schrader. I verified there IS fuel there by partially removing the FP guage and swapped back in the old chip just for kicks (same problem)

What in the world in stopping me?

Thanks..
Eric

 

It could be the FPR, it might not be holding pressure.

You say "the pump primes as normal (scanner shows voltage)". Did you verify that by listening to the pump or by measuring voltage on it? The computer might think it's sending voltage to the pump but in fact, no fuel might be pumping. If you need to troubleshoot the fuel pump circuit, feel free to AIM me, I've done this a hundred times over the net.

Lou

 

sounds like it might be time to put a 255lph in there

 

Lone Star: I have that Walbro unit in now, installed it in April

BBL: I verified by listening and reading the scanner. I know there at least some fuel there by the schrader valve. I'm going to unhook the feed line and make sure I'm getting a good prime, then I suppose I'll unhook the lines at the manifold and blow them out (blockage?). May even un-do the fuel rail and blow it out too. This seems like a blockage, but I couldn't explain why I think that way.

Thank you both for the reply.

 

how old is the fuel filter?

see if you can check what the psi is before the fpr

 

How long was it shut down for? Did you cap off the fuel lines while working on the engine?

I'm asking because where I live, there are so many of those dirtbugs and spiders and such that if you leave something uncapped for a day or two, they WILL nest inside and totally plug the line with dirt and their tiny bodies. You might just be unlucky enough to experience that.

Lou

 

No it wasn't capped off the entire time.

I primed it with the feed line emtying into a bucket and got a healthy shot. I don't know what to look for as far as that being enough....

I don't get the 12V jumper thing to the ALDL to fire the pump. Maybe I need to do that? If so how?

Ack, I thought I had a good lead but I'm not going any further until I feel comfortable that I won't be replacing my 3rd pump in 3 years. This is a real pisser....

 

I got the FP guage hooked up to the hard line in the engine bay (coming from under the car). I DID get an instant spike of 60 lbs, but once it got there, the pump stops priming (after the 2 second shot), the pressure pops the relief valve, and the pressure bleeds off completely in under a minute.

To recap: no pressure at rail, plenty of pressure at line with instant bleed off.

 

I started having some pressure issues with my car. It would run, but be starving for fuel and the guage stopped working.
When I had my rear end out I had to remove the tank anyway because there was a leak, which turned out to be the sending unit O ring. I decided to be safe and replace the pump even though it was a newer Walbro since it was all apart anyway.
Turns out the hose clamps on the feed line in the tank, the short piece of rubber hose connecting the pump to the hardline had come loose.. vibration maybe? So I am guessing fuel was able to leak there.

Which line did you put the gauge on? the larger supply line or the smaller return line?

 

The guage is on the bigger line.

I didn't think it was possible, but could I have reversed them? 60-80 pounds of pressure lost between the line and the rail is twilight zone stuff!

I blew the rubber line, and both hard lines that run beside the alt out with compressed air. I somewhat got the air nozzle into the rail fitting and blew them out too. Some air came out the other end......No debris came out of the lines of course. For what it's worth, this is not the same rail I took off the car, however it is a powercoated set I got from the west coast. I blew them out before I put them on the car so I'm at a loss here.

 

ok if you have 60psi before it goes the the FPR, im going to say your afpr is likely the problem.... if you have the stock frp still, try to put that back on and see what happens.

what fpr do you have on there?

 

I agree with LoneStar, it sounds like the FPR might be the possible cause.
If you can disconnect the return line at the fuel rail and cap the rail, would you build up pressure in the rail?

Howdy from Austin, LoneStar.

Lou

 

I like that neither of you said to just replace the fuel pump. haha

Seriously, I was going to remove the whole rail and try to check for a blockage but I am going to do what you guys suggested first as it makes the most sense. Boring NASCAR race this weekend so Sunday will be the day!

 

BigBabyLou: you should register on TexasFbody.org, have a lot of local gatherings/wrenching with each other on the forum... lots of knowledge and people willing to lend hands... not to mention fast cars


Boss 355: ive noticed that with aftermarket afpr's they have problems with seals going bad and not working at all anymore, no matter what brand (holley, bbk, tpis etc) hopefully its just the FPR and not the fuel pump, for the third time apparently. you say that the psi doesnt change no matter how much you adjust the fpr, so maybe something has collapsed inside it causing almost no fuel to be allowed through

 

If the gauge is on the supply line, put it in front of the rubber hose then pinch off the rubber hose. If the pressure bleeds off real quick then the problem is before the FPR, like either the check valve in the pump or a loose line in the tank like I suggested. If it holds pressure, then pinch off the only the return line.

If it holds pressure now then it's likely your FPR. If it still leaks, it could be the injectors.
If you can get it to hold pressure and quickly pinch off both lines, that will show if the injectors are leaking if it still bleeds off.

Of course this is with everything all connected as normal.

 

just a thought here.. u shouldnt have 60 psi in a return line.. u should have that in a supply line.. have u tried starting the car yet? maybe u have the lines on right but the gauge on the wrong line.. and pressure does bleed of relatively quick in my car as well

 

91 355: the guage is on the supply line

Jay: my whole problem is I can't get the rail to pressurize. Like I posted above, I'm gonna tinker with the FPR then I may just reassemble the rail to make sure there's no blockages and everything is hooked up right. I know all about piching off lines, I replaced a pump a couple months ago! haha Once I get pressure in the rail, then I will work on bleed-off, if any by that time.

 

Tale Of The Tape for this weekend: I tried..

2 different schrader valves
2 different fuel rails
2 differnt fuel pressure regulators
found no leaking injectors
found no leaks at any of the connections
all hard and rubber lines are clear of obstruction
both fuel rails are clear of obstruction


What now?

 

The final Jeopardy answer is: the valve on the FP guage was broken. A $10 part fixed it.

One interesting note, of the 2 fuel rails, the one I took off held pressure longer than the "new" one. That seems odd to me, but I tested both for a couple of hours with the injectors hooked up and got the same result. A little paint and the original piece looks (and works) pretty good.

Thank to all to helped me out here.
Eric