LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

symptoms of a bad fuel pump

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Old Mar 22, 2004 | 08:55 PM
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Haskin Z28's Avatar
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From: Bonita Springs, Florida, USA
symptoms of a bad fuel pump

list a few symptoms of when ur fuel pump is on its way out, i think mine is but was just wanting to know from others experiences, it sputters and bog every now and then while im cruising
Old Mar 22, 2004 | 08:58 PM
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95 3.8's Avatar
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somethimes it wont start, like if it was outta gas. I had to change mine, from a hole cut on the trunk. $125 at summit, I think. but after that, the gas gauge its messed up.
Old Mar 22, 2004 | 09:19 PM
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Mine was very hard to start. I got the racetronix one from thunder racing for 150. Included wiring harness and stuff. And it's good to 800 HP.
Old Mar 22, 2004 | 09:36 PM
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I'm wondering also. I've got a pressure gauge, when you turn it on the pressure seems to go up too slowly- several seconds to get to 40?- usually doesn't get that high unless I turn off and on again. Pressure drops back down, too, but I'm assuming that's thanks to my Holley afpr, seems too quick to be an injector leaking...

My car also refuses to start at 1st crank sometimes, then crank again and starts right up. Confuses the heck out of me.
Old Mar 22, 2004 | 09:53 PM
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i think i totally TOTALLY misdiagnosed my problem, i wa sjust at the gas station and i heard a shrieking from under my hood, popped it and noticed the ac compressor appars to be locked up
Old Mar 22, 2004 | 09:57 PM
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That sucks.
LT1s seem to have a lot of quirky problems, but never really seem to totally give up.
Old Mar 23, 2004 | 02:33 PM
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im not totally sure, but my car started to act up. it was idleing like it had a cam and the slightest amount of throttle would almost kill the engine. first i noticed that i had my air temp. sensor unpluged, i shut the engine off pluged it back in and went to restart it and it wouldnt fire. not sure if its the fuel pump because before it wouldnt start it sounded like it was already getting too much fuel
Old Mar 23, 2004 | 04:20 PM
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Best thing to do is test to see if it is the fuel pump rather than trying to guess. Get a fuel pressure gauge and hook it up to the fuel test port on the fuel rail one the back of the intake manifold. Turn the key to the on position, the pump should prime and the presssure should shoot up to about 40PSI and HOLD steady, NOT drop off right away. Then start the car, it should drop slightly but stay near the 40PSI mark.
Old Aug 6, 2021 | 02:56 PM
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Re: symptoms of a bad fuel pump

Originally Posted by greendemon
i'm wondering also. I've got a pressure gauge, when you turn it on the pressure seems to go up too slowly- several seconds to get to 40?- usually doesn't get that high unless i turn off and on again. Pressure drops back down, too, but i'm assuming that's thanks to my holley afpr, seems too quick to be an injector leaking...

My car also refuses to start at 1st crank sometimes, then crank again and starts right up. Confuses the heck out of me.


have you figured that out mine does the same exact thing
Old Aug 6, 2021 | 03:45 PM
  #10  
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Re: symptoms of a bad fuel pump

“GreenDemon” hasn’t signed into this site since 2012.

Are you saying you measured the fuel pressure, and it was exactly the same results?

Pump only runs for 2 seconds to prime, then shuts off. Should reach at least 40 PSI at that point. Should hold pressure or drop very slowly. If it drops rapidly and suffers from slow start, could be:

- leaking injector(s)

- leaking fuel pressure regulator

- leaking fuel line, including the flex connector in the tank

- faulty check valve in fuel pump

-
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