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

Possible Bad Fuel Pump?

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Old Mar 22, 2004 | 06:23 PM
  #1  
Fast96WS6's Avatar
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From: Bergen County, NJ
Exclamation Possible Bad Fuel Pump?

My stock FP has about 130K on it and I think its about to go. Here are the symptoms...

-Hard starting (takes about 10-15 seconds to start cold)
-Doesnt seem to pull hard to redline anymore (seems to slightly fall off in power around 4500)
-Once in a while, flooring it with around 1/4 tank of gas in 2nd gear, the car will slightly die for a second then kick back in.
-When cold, the cars idle will drop then kick back in at lights

From what I've searched, these seem to be the symptoms of a bad fuel pump. The opti, fuel filter, Wires, Plugs, and Coil all have about 10 K on them. I replaced all at the same time when I had another problem.

What does everyone think? I'm about to order the Racetronix unit. My friend has the same unit and raves about it.

TIA
Old Mar 22, 2004 | 06:53 PM
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Fast96WS6's Avatar
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From: Bergen County, NJ
anyone??
Old Mar 22, 2004 | 06:59 PM
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From: Statesville NC
are you throwing a code? a loss of the high res signal from the opti can hurt performance as well as cause extended cranking times.


a fuel pressure test will tell you whats going on with the fuel pump. run this test and see what you have


Install the fuel pressure gauge onto the shreader valve on the fuel rail. a picture can be found here http://shbox.com/1/fuel_schrader_valve.jpg
Once you have the gauge installed turn the key on but leave the engine off. this is the first key position BEFORE start and is refered to as KOEO (Key On Engine Off)

With KOEO the fuel pressure should imediatly go to 43.5psi +/- 2 PSI


Now watch the gauge and see if the pressure stays or if it bleeds down. if it bleeds down slowly you could have a leak in the system, a bad injector, a bad regulator. if you ahve a very fast bleed down it could be the check valve in the pump. this would usualy make for a hard start/bad high load perfromance.


don;t forget to check teh fuel filter
Old Mar 22, 2004 | 07:28 PM
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From: Bergen County, NJ
i'm not throwing a code at all. I'll check the FP tomrow and see if this is the problem. My friend's Fuel Pump went on him and he was holding great FP with the key in the on position. He was getting back losses of power at high rpm's though. The pump ended up failing on him when the car wouldnt start one morning.

Would a bad Crank Pos Sensor give me the same symptoms I was talking about earlier?
Old Mar 22, 2004 | 07:29 PM
  #5  
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From: Birmingham, Al
Sounds like the pump to me, but to be sure, do the test.
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