Young Maro

iTrader: (5)

Having another fuel issue with my 383 stroker 93 z28. The first issue was no fuel was getting to the rails. A line had gotten kinked on the fuel pump.. fixed it, now fuel is getting up to the rails, BUT -

I'm only getting 15psi at prime. I have tried priming it multiple times and bleeding the lines with the gauge with no luck. The gauge jumps to 15psi then goes right back down to 0 right away, key on ignition off. It doesn't stay at 15, which I thought was weird, but not sure.

Then when I start the car, I'm getting about 25-28 psi at idle, with no variance in pressure if you give it gas at all.

I've got an adjustable fuel pressure regulator, but no matter what adjustment I make on it, the pressure remains low. Brand new fuel filter. I pulled the fuel line before the filter, turn the key forward to prime, and gas pours out at a decent rate. It doesn't come out under really high pressure, but it comes pours out about 1-2 feet from the line.

Where should I look to? The only thing I can think of is if somehow a line is kinked on the fuel pump again, or something similar. If anyone has any ideas, please, I'm all ears! Thanks guys

Lonnies Performance

iTrader: (16)

Chances are your line in the tank is leaking or ruptured.

You should not be using rubber lines in the tank.... they frequently blow out.

Young Maro

iTrader: (5)

I will have to pull the pump back out and check.... What should I use, braided steel line?

Young Maro

iTrader: (5)

And is that the ONLY thing it could be?

RamAir95TA

iTrader: (2)

What was wrong with the stock fuel pump assembly, lines, regulator and hoses? The need to upgrade them is about 250HP away.

The AFPR is also a poor choice - completely unnecessary. I would start by pulling the tank and replacing the pump assembly with factory (or equivalent) plastic fuel tubing (Racetronix can supply you with these parts), and ditch the AFPR as they can often cause more trouble than good.

Notice the trend here - stock parts work. If it ain't broke, don't fix it.

Young Maro

iTrader: (5)

Well with 180k on the stock fuel pump, and a 200hp increase in power it seemed like common sense to upgrade the pump.

I might try and swap the stock FPR on and see if that helps.... Gonna pull the pump back out too and check the lines, maybe get braided steel lines.

Young Maro

iTrader: (5)

When checking the pressure at prime should it stay pinned? When I check it, it's jumping up to 15 then going back down to 0 right away.

StangeatinZ28

fuel pressure should prime and hold. looks like you have a weak pump on your hands

RamAir95TA

iTrader: (2)

I said fuel pump assembly, not fuel pump. I meant the internal parts that the pump attaches to, including the lines.

You either have a very weak pump, stuck injector, bad regulator, or broken lines in the tank.

Young Maro

iTrader: (5)

Damn.... I will have to check the lines, and hopefully swap out the pump. Is there any way to test for a stuck injector?

RamAir95TA

iTrader: (2)

Yep, and it's fairly easy. Remove the four bolts holding down the fuel rail and pop out the fuel rail (injectors and all). Hold up the rail and have someone urn the key to ON to prime the pump. If ANY of them drip or spray you've got a bad injector.

It would also be apparent in that injector's corresponding cylinder by looking at the spark plug.

Young Maro

iTrader: (5)

Cool thanks for the help guys. I'm going to check the lines first... it seems like it has to be a punctured line, since it's not holding pressure when you prime it... I will investigate and report back.

fex77k

iTrader: (2)

It is a requirement for the stock FPR to hold pressure for a little bit after the car is shut down. Aeromotive states on the instructions for their AFPR that they will not hold pressure after the car is shut down. I looked on there site for it but I didn't see it, I know I read it when I installed mine.

Young Maro

iTrader: (5)

Think I found the problem today. I pulled the pump back out, kept the bottom submerged in gas, and primed her over. Gas shot out the plastic accordion hose.. it had a cut in it.

So I used some rubber fuel hose and made a new line, primed it over.. the hose held up just fine, but gas started spraying out of a small hole next to the outlet on the pump. I called SpeedTweekerz and they said that hole is just a freezeplug type deal and nothing should be coming out of it.

So I guess I've got a bad pump now too lol. Getting it warrantied out and we will see what happens!

Young Maro

iTrader: (5)

Lonnies Performance

iTrader: (16)

Trying to run a pump partially submerged in fuel is a good way to end up in a burn unit.

Pumps are not explosion proof, they only are safe because there is not enough oxygen (read too rich of a mixture to burn) in the tank to explode.

My first post stated not to use rubber hose in the tank.....

Are you planning to remove it again?

Young Maro

iTrader: (5)

I only used the rubber hose as a temporary fix to see if the pressure raised or not, I was planning on using some braided lines when I reinstalled it.

My last post stated I sent the pump in for warranty.

So the next time I install the pump it will be with braided lines and hose clamps on every connection.

Why would a fuel pump explode randomly just because it is exposed to air...?

fex77k

iTrader: (2)

Well if you get the right mix of gas and air you will support combustion.

Young Maro

iTrader: (5)

Got the new pump in, got rid of the bucket, all is well

RamAir95TA

iTrader: (2)

Why did you remove the bucket?