lunaticinaZ

When I turn the key on engine off with a fuel pressure gage hooked up. At first all I got was about 28psi. I started the car and at idle was only getting about 38psi. I pinched off the return line and the fuel pressure went to about 47psi but as soon as I let go of the return line it instantly goes back to 38psi. So I shut off the car and waited a few min and then with the return line still pinched off I turned on the key. The fuel pressure didn't even move up at all.
So with that, what do you guys think. Is it my fuel pump? or the fuel pressure regulator? Also it has a brand new fuel filter on it.

ninetyone

iTrader: (2)

First of all, what type of problem are you having with your car? Proper way to check Fp is to disconnect Fuel pressure regulator vacuum line and cap it. Hook up Fp gauge and start car. Check it while car is idling. Should be around 43.5 psi (stock GM). 47 is probably fine. Once you uncap the hose it should drop. nothing wrong with that.

lunaticinaZ

Well I started the car at work one day. It would idle but when I would try to take off it would jerk and the engine would act like it was being choked, I could rev it up but couldn't drive.. I limped it in the shop and hooked up a fuel pressure gauge and it read only 25psi with the engine off key on. So I thought the fuel pump was bad. But I started it to drive it out of the shop and she ran fine. But when I would drive when I would give the car more that half throttle she would hesitate a little but as long as I drive easy the car would run fine. So I drove her home and have been driving my truck fot 2 months lol
So today I did what I said in my first post. I thought it should have 43 or so psi when you turn the key on and the pump primes? And while the car is running it should be about the same psi all the time? The only time it will have anywhere near 43 psi is if I pinch off the fuel return line? Is this normal? Should I be looking for a different cause of the problem?

ninetyone

iTrader: (2)

you should have 43 psi when the gauge is hookup and the vacuum line is disconnected and the car is idling. Disconnecting and plugging the vacuum line simulates WOT fuel pressure. when u hook the line back up the pressure should drop like 7-10 psi or so.

ninetyone

iTrader: (2)

try the simple stuff first, do you have any codes? check for them, change your fuel filter. Ohm your injectors.

ninetyone

iTrader: (2)

How are you pinching off the return line? Isn't it made of metal?

lunaticinaZ

the fuel filter is brand new, that was the first thing i replaced. i ohmed the injectors a while back before this problem started. I'll check them again. No codes. And there is a short section of rubber fuel line between the metal lines that go to the tank and the metal lines that run to the fuel rail. it"s about 8" long. I pinched that off with vise grips. But I'll go outside right now and try the unplugging the vac line from the regulator. Stay tuned

lunaticinaZ

Ok, I went outside. And with the help of my lovely assistant lol my wife. I took the vac line lose and plugged it. My wife started my car and it idled while showing right around 43-45 psi. I unplugged the line and hooked it back up and it dropped like you said about 7-10 psi. So.........I guess I was wrong thinking it was fuel pressure.

ninetyone

iTrader: (2)

http://www.youtube.com/watch?v=_g8PdrT0MCU

check out the video, ohm your injectors again so we can rule them out.

ninetyone

iTrader: (2)

You know how to check for codes too?

lunaticinaZ

ok I'll do that now. And yes I know how to check for codes. I keep a paper clip in my car at all times

ninetyone

iTrader: (2)

If all of your injectors are good, i would move on to checking the timing.

lunaticinaZ

Ok, 7 of them was 16.3 and the last one was 16.2. And I thought about checking the timing and never could find my timing light. But I'll look again for it. I just moved and crammed all my tools from a 20'x20' building into a 8'x8' so it's a big mess.

lunaticinaZ

Ok, I found my timing light. I disconnected the one wire connector and checked the timing. The scale on the block goes to 12* And the timing mark was probably 2-3 degrees above that. So it was somewhere around 14 or 15 degrees base timing. So I set it back to 6 degrees.

ninetyone

iTrader: (2)

look at the attachment. You said you did disconnect the EST (brown wire/black strip) near the blower motor? Then reset your ecm by disconnecting negative battery cable for a few minutes?

ninetyone

iTrader: (2)

So, how is it running now?

lunaticinaZ

In the pic, where the red line is that's above +12. Thats about where the timing mark was. And yea the EST. I couldn't remember what it was called. I haven't disconnected the batt. yet But I'm getting ready to do that. I did rev her up a few times and there seemed to be no hesitation. But I'm going to drive to the gas station about 2 miles down the road and see if the hard acceleration hesitation is gone.

ninetyone

iTrader: (2)

that would be 14. Disconnect neg. battery cable first and then take her up to the gas station.

lunaticinaZ

OK, I drove to the gas station. There was still hesitation on hard acceleration. Put gas in and started the car. Car died and wouldn't start back. I hooked up the fuel pressure gage and all I was getting was maybe 5psi. So I towed the car back home and I guess I'm putting a fuel pump in tomorrow.