dragracemaniac

have a 2 door 97 tahoe with 249K on it. working on fuel pump #7. just changed most recent one a week ago and having problems again. everything fine for a couple of days, then while on highway it progressively loses power until you can't continue any more. shut it off and on and everything is ok for 10 minutes or so, then problem surfaces again.
original problem started years ago - chevy put in 3 different pumps over the course of 18 months. also changed wiring harness to pump and regulator.
warranty expired and I put a NAPA pump in and it lasted for years. NAPA pump died this summer. Now here we go again.
Most recent pump has only been in there for a week and never dropped below half a tank of gas.
Please help.

lpmZ71

[align=left]Drag,

First thing I feel needs to be done is take the fuel filter off and put the inlet end into a clear bottle and drain it.
Let the fuel settle and check for contamination (ie water,rust,excessive dirt)contamination will eat up a pump in no time at all.
When was the last time the fuel filter was replaced?
Because a dirty fuel filter will cause fuel pump amperage to rise and cause pump to overheat also.
Next thing to check is the connector for overheating at the ground terminal.


Mike
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73shark

Welcome both of you to the Tahoe forum. Good to see that one newbie can help another.

ZX1100F1

Welcome.
Normally repeated fuel pump failures are caused by a damaged fuel pump module connector, replace the connector with GM part #88988598 and be sure to use the splice sleeves provided in the package with the new connector.

dragracemaniac

thanks for the help so far guys. fuel filter was changed with the pump and have always been changed regularly. fuel tank was spotless when last pump was changed, so I don't suspect dirt or a clog.
I bypassed the entire wiring harness with a jumper wire from the underhood fuse center to the pump. problem still occurs. sometimes problem doesn't surface for an hour - i drove the truck sunday for an hour without a problem until I was almost home, then step on the gas and it has no power and stumbles. step on it again and the stumble gets worse and worse until you have no power at all.
at this point, what's left in the system? pressure regulator or another bad pump?
is there any way to test the regulator without pulling it or should I go ahead and change it?
thanks

ZX1100F1

I should have been more clear.
Your fuel pump is probably shot and it most likely was caused by a bad connector.
Replace the pump and the connector.

aztecf

ZX, could a vacuum be forming in the tank?, how does air get in with our new fangled emission vehicles

Jeff

ZX1100F1

Jeff,
Nope, The fuel tank EVAP system is designed to operate with a slight amount of vacuum; if there is excess vacuum then the VCM will set a DTC and you will get a warning light. This system is very sensitive and will trigger if you don't get the gas cap tight.

dragracemaniac

ZX, is this wiring harness prone to repeated failures? when this problem first plagued me about 7-8 years ago, the harness was replaced by chevy. they went through 3 pumps and a napa pump finally did the job after the year warranty had expired on the replacement part.

ZX1100F1

Yes it is, the new connector is likely an update to what was used to make the repair 7-8 years ago.
There was also an issue with some technicians not installing the new connector properly.