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Old 04-25-2012   #1
groingo
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1990 GTA fuel system problem

1990 GTA with 305 TPI
Tested fuel pressure at the engine and it shows 20 to 25 pounds then when shut off immediately drops to zero.
Had fuel pump replaced four months ago....any ideas?
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Old 04-26-2012   #2
merc3065
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Re: 1990 GTA fuel system problem

leaking injectors, fuel pressure regulator diaphragm could be damaged.
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Old 04-26-2012   #3
groingo
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Re: 1990 GTA fuel system problem

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Originally Posted by merc3065 View Post
leaking injectors, fuel pressure regulator diaphragm could be damaged.
I can safely assume that would also cause the fast bleeding off of fuel pressure as well....will give it a shot.
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Old 04-26-2012   #4
GTAhot92
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Re: 1990 GTA fuel system problem

If the injectors are leaking it would smell as if you flooded the motor. If the FPR is leaking it will just keep recirculating the fuel through the system back into the tank. To test that hook a mighty vac hand pump to the FPR and apply vacuum to see if fuel pressure lowers. With the vacuum disconected from the FPR the pressure should be at it's highest.
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Old 04-26-2012   #5
groingo
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Re: 1990 GTA fuel system problem

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Originally Posted by GTAhot92 View Post
If the injectors are leaking it would smell as if you flooded the motor. If the FPR is leaking it will just keep recirculating the fuel through the system back into the tank. To test that hook a mighty vac hand pump to the FPR and apply vacuum to see if fuel pressure lowers. With the vacuum disconected from the FPR the pressure should be at it's highest.
All I get from the mechanic is a song and dance so am pulling the car out of the shop and will do the work myself....couldn't do any worse.
There is no fuel smell and quite honestly I just don't think the mechanic has a clue what he is doing even though he came highly and had worked at the Chevy dealer for eleven years.
The plan is to try to get it running respectable and dump it, this car has "Money Pit" written all over it.
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Old 04-26-2012   #6
merc3065
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Re: 1990 GTA fuel system problem

Working at a Chevy Dealer for eleven years means nothing if it was the last 11 years.

I would sooner trust the grungy old guy in a shop that looks like it's something out of the nuclear apocolypse than a dealership or a name brand place.

And yes, these are can very well be a money pit. Doing work yourself and finding bargain prices on parts can save money and time. You're either committed to it or like you said, get it running and get it gone.
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Old 04-26-2012   #7
prokilllsx
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Re: 1990 GTA fuel system problem

I would try replacing the fuel pressure regulator first.
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Old 04-27-2012   #8
groingo
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Re: 1990 GTA fuel system problem

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I would try replacing the fuel pressure regulator first.
I will be replacing the bladder in the regulator regardless but what I can't figure out is if the pump was bad I would expect high speed performance to be bad due to fuel starvation and it is not, that is where it works best, nail the gas and it will pin you to the seat and not miss a beat.

The reason I wanted it done "Professionally" is for the warranty which includes labor.
Doing it myself, the parts today are of such poor quality that when they do prematurely fail all you get is another P.O.S. and nothing for your time.
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Old 04-28-2012   #9
YumikoGTA
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Re: 1990 GTA fuel system problem

Yes a lot of mechanics do not know anything about how to work on GTAs because most of those guys who did know are now retired. Every time I drive my GTA to the GM Dealership, so many of the guys come to look at it, they seem to appreciate it the most. About thirteen years ago, I had a neighbor at my old house where I lived at that time and he was retired from GM. He loved coming over and talking to me about my GTA when I would be doing something to it like changing the engine oil, etc. So maybe you can some way find someone like that who used to work on these GTAs when they were new GM cars and they can help you. The recent problems I have encountered with my GTA however is the mechanics at the smog stations when I bring my GTA in there for the smog testing. So many of them do not know much about how to test these GTAs. Some do not know to disconnect that wire when adjusting the timing and some do not know to do the smog test while the car is in the third drive gear and not the overdrive gear. It is basically manditory that we watch them do the smog test and inspection because they do not know all about it and we usually would be there for an hour or more because they are trying to figure it out. It is an advantage to have owned these GTAs since they were new because I know so much about my car that many of the mechanics do not know since they never have experiences working on them. The new cars of today are so different now and they have most of their experiences with the new ones only. Good luck.

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Last edited by YumikoGTA; 04-28-2012 at 01:13 PM.
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Old 04-28-2012   #10
groingo
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Re: 1990 GTA fuel system problem

It is so frustrating these "ASE Mechanic's", I am going to try one more fuel pressure test with a T gauge back at the pump myself, and I did just test the fuel pressure regulator three times today (each test 15 minutes) and no problem.
The baffling thing is the fuel pressure reads at the rail 20 to 25 pounds and when I turn the engine off it immediately drops to zero yet the car when driven hard runs like a raped ape!
This car is so right, the only flaws left to fix were the tiny wear through on the drivers seat side bolster, headliner and one interior trim button otherwise the car is in excellent shape....and then this started and pretty much drained the budget for everything else....sucks.
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