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New fuel pump not working

Tiny
MATTGUITAR
  • MEMBER
  • 1998 CHEVROLET SUBURBAN
  • V8
  • 4WD
  • AUTOMATIC
  • 111,000 MILES
The truck died a couple of months back and I determined the fuel pump wasn't working. I replaced the relay and the pump. Now the pump is not working again. I also replaced the ignition control module. When I turn the key to the on position, the theft deterrent system makes a double clicking noise. I can't recall if that is normal. With the key on, I have closed the contact on the relay and still don't get the fuel pump on. The fuses are all good. I suspect that this is either the theft deterrent system or the ignition cylinder. How do I determine where the fault is before I pour more money into parts. Thanks for any help.
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Thursday, May 1st, 2008 AT 8:56 AM

10 Replies

Tiny
BUZZSAW
  • MECHANIC
  • 1,198 POSTS
Does it crank or turn over? While its turning over is the scurity light on? Theft sys disables the starter

I need your engine size for a wirring diagram for the pump and if you have duel tanks
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Thursday, May 1st, 2008 AT 10:37 AM
Tiny
MATTGUITAR
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  • 3 POSTS
Turns over fine. The security light stays on for the first few seconds of cranking and then goes out.

It's a 5.7 (350) with single tank. Thanks for the quick response.
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Thursday, May 1st, 2008 AT 11:16 AM
Tiny
BUZZSAW
  • MECHANIC
  • 1,198 POSTS
Does it crank or turn over? While its turning over is the security light on? Theft sys disables the starter
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Thursday, May 1st, 2008 AT 11:51 AM
Tiny
MATTGUITAR
  • MEMBER
  • 3 POSTS
Turns over fine. The security light stays on for the first few seconds of cranking and then goes out.

It's a 5.7 (350) with single tank. Thanks for the quick response.
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Thursday, May 1st, 2008 AT 12:00 PM
Tiny
BUZZSAW
  • MECHANIC
  • 1,198 POSTS
Ok hope your good with wiring diagrams, you can call me if you need some help reading them
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Thursday, May 1st, 2008 AT 12:09 PM
Tiny
RRANDALL22
  • MEMBER
  • 1 POST
  • 1997 CHEVROLET SUBURBAN
Electrical problem V8 Four Wheel Drive Automatic 169000 miles

Truck will not start on occasion, mostly first thing in the morning. Later in the day it will start and run fine. One time I drove 25 miles into town and it wouldn't start after stopping at a parts store. Have replaced the entire fuel pump assembly with OEM dephi pump; replaced fuel pump relay; fuel filter, entire intake injection assembly and plug wires recently replaced. When it won't start the fuel pump does not run. Checked by no pressure/fuel at the valve near the intake and got engineer to start by spraying carburetor cleaner into the intake.

What are the probable causes for the fuel pump not running? What should I try replacing next?

I can't find the red wire for the fuel pump test connector. Please be more specific on where to find it.
Also, my vehicle is equipped to run on propane gas as well as gasoline. Could the additional electrical module added under the ECM have anything to do with my problems with the fuel pump not running intermittently?

The suburban is currently running so it is hard figure out what is wrong. Two days ago it wouldn't start early in the morning, but ran fine later in the morning and has run fine ever since. I expect it will not start at sometime in the future and I want to be prepared. If I make up a jumper wire for the pump test connector a head of time at least I will have the capability to get it running in short order.
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Wednesday, January 8th, 2020 AT 12:42 PM (Merged)
Tiny
GETAWAYCARS
  • MEMBER
  • 9 POSTS
Any updates? I have a similar problem.

My truck has not started on two occasions, most recently yesterday. It starts later and is ok, but seems to crank a little longer before starting.

My system doesn't hold fuel pressure, with key on (but not running) pressure goes to 45 psi, but drops to below 10 psi in about 30 seconds.

Any ideas?
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Wednesday, January 8th, 2020 AT 12:42 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,702 POSTS
Hello,

It sounds like the fuel pump relay is not working or there is a power supply issue. Here are some guides to help you test for the problem along with a fuel pump wiring diagram (below). Test to see where you are loosing the power from.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

and

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

I gave you all of the engine wiring diagrams in case it could help.

Please run some tests and get back to us so we can continue helping you.

Cheers, Ken
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Wednesday, January 8th, 2020 AT 12:42 PM (Merged)
Tiny
MT MAN
  • MEMBER
  • 1 POST
My fuel pump keep stop pumping so we found the hot wire going to it and cut it ran a key hot wire to it buy passed the computer and it don't stop pumping now the computer keep shutting the pump off, but I bypassed most of the computer went back old school. Because the anti-theft would shut it down. So I went a round it yes old school with a Vortec 350 will worth the money and work song a 400 turbo transmission is going in it.
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Wednesday, January 8th, 2020 AT 12:42 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,702 POSTS
So is it running or are you swapping the engine out? Do you need any diagrams form us?
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Wednesday, January 8th, 2020 AT 12:42 PM (Merged)

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