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'96 Z71 Will Not Start

jeffk14

By jeffk14
in Ask A GM Technician

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jeffk14 Enthusiast

jeffk14

Posted
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My son just called me from out of town (he's away at college). 1996 Z71 with 5.7 eng. He parked it yesterday and all was normal. Today, engine turns over, but no start. Plugs and fuel filter changed about 1K miles ago.

 

I'm a (aircraft) mechanic by trade so I know a little about mechanical stuff, but it's hard to diagnose over the phone long distance.

 

Can any GM guru give me a "quick and dirty" for me to suggest he try? Thanks.

Nytemare Senior Enthusiast

Nytemare

Posted
Posted

Ask him if he hears the fuel pump doing its priming cycle when he turns the key to the run position...ie the position just before crank.

jeffk14 Enthusiast

jeffk14

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Ask him if he hears the fuel pump doing its priming cycle when he turns the key to the run position...ie the position just before crank.

Thanks Nytemare. I thought about that, but I don't remember ever hearing that electric fuel pump run. I'll get him to check it though. If that pump is bad, that's a tank drop, right?

Nytemare Senior Enthusiast

Nytemare

Posted
Posted
Ask him if he hears the fuel pump doing its priming cycle when he turns the key to the run position...ie the position just before crank.

Thanks Nytemare. I thought about that, but I don't remember ever hearing that electric fuel pump run. I'll get him to check it though. If that pump is bad, that's a tank drop, right?

 

The pump makes a humming sound for about 3 seconds when you put the key in run...thats the priming cycle.

 

If the pump is gone its easier to pull the bed bolts and slide it back than it is to drop the tank. you can access the pump from the top and drop a new one right in...takes about 4 hrs to move the bed replace the pump and button everything back up.

jeffk14 Enthusiast

jeffk14

Posted
  • Author
Posted
Ask him if he hears the fuel pump doing its priming cycle when he turns the key to the run position...ie the position just before crank.

Thanks Nytemare. I thought about that, but I don't remember ever hearing that electric fuel pump run. I'll get him to check it though. If that pump is bad, that's a tank drop, right?

 

The pump makes a humming sound for about 3 seconds when you put the key in run...thats the priming cycle.

 

If the pump is gone its easier to pull the bed bolts and slide it back than it is to drop the tank. you can access the pump from the top and drop a new one right in...takes about 4 hrs to move the bed replace the pump and button everything back up.

 

 

Thanks. Of course, I'll have him check for power to the pump first. Any idea where the fuse is for that pump? Man, it's hard trying to diagnose/make decisions long distance.

Nytemare Senior Enthusiast

Nytemare

Posted
Posted

Its under the hood I believe...marked F pump or fuel...or something similar.

 

There is also a relay that goes with that. Tell him to swap it with one that has the same part number in the relay box...there should be several.

 

There is a red bypass wire with a black clip on the end that usually sticks out of the harness right beside the cowl on the drivers side. This wire can be used to test the pump by putting battery voltage directly to the pump...caution should be used though as it is un-fused voltage and can cause a fire in the fuel tank if something is wrong with the pump.

jeffk14 Enthusiast

jeffk14

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Nytemare, thanks again for all your help.

 

My son is now monitoring this thread. He's a smart young man, just hasn't had much mechanical experience.

 

He found the relay. I had him turn the key to "on" while someone held their finger on the relay. The relay is engaging.

 

BTW, he already checked for the sound of the pump and either it's dead or he's not hearing it.

 

Sounds like the pump may be the culprit. The truck is a stepside. Will that bed be any different/harder to disconnect/slide back than a fleetside? I'm reluctant to have him try to drop the tank.

Nytemare Senior Enthusiast

Nytemare

Posted
Posted
Nytemare, thanks again for all your help.

 

My son is now monitoring this thread. He's a smart young man, just hasn't had much mechanical experience.

 

He found the relay. I had him turn the key to "on" while someone held their finger on the relay. The relay is engaging.

 

BTW, he already checked for the sound of the pump and either it's dead or he's not hearing it.

 

Sounds like the pump may be the culprit. The truck is a stepside. Will that bed be any different/harder to disconnect/slide back than a fleetside? I'm reluctant to have him try to drop the tank.

yeah its a blatantly audible sound...he would hear it.

 

The bed shouldn't be any harder...I have never done a Stepside...I also drop the tank too...but I have a shop to do it in and a trans jack to lower it down. I'm not laying on my back in a parking lot or driveway.

All he should have to do is unbolt the body mount bolts and maybe unhook the tail lights to get the play to move the box...him and a buddy should be able to move it back. Than you have a clear path down to the pump...you disconnect the pump, remove the locking ring, pull it out and replace in reverse order. And while he's at it...a good idea with a new pump is to change the filter...it should be on the frame rail under the drivers door.

jeffk14 Enthusiast

jeffk14

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Update: There's a "friend of a friend", who lives down there, who is a tech at a dealership and does work on the side. He looked at the truck and confirmed that the pump is bad. He'll change it out for $120 labor. I think that's more than fair. There's an Oreilly's down there that carries the Delphi pump for about $119.

 

Since the truck is 130 miles from me, I think I'm gonna let this guy do the job.

 

Nytemare, is the Delphi pump the way to go? There are cheaper options, but I figured I'd be better off with OEM.

Nytemare Senior Enthusiast

Nytemare

Posted
Posted

OEM will last longer and perform like its supposed to...most cheap ones last for a year or 2 before they start giving problems...and being in school, he doesn't need to pay 200 bucks every year or 2 on fuel pumps.

$240 is a good price for a pump change for sure.

jeffk14 Enthusiast

jeffk14

Posted
  • Author
Posted
OEM will last longer and perform like its supposed to...most cheap ones last for a year or 2 before they start giving problems...and being in school, he doesn't need to pay 200 bucks every year or 2 on fuel pumps.

$240 is a good price for a pump change for sure.

 

Delphi it is then! Thanks again for all the help.

Nytemare Senior Enthusiast

Nytemare

Posted
Posted
OEM will last longer and perform like its supposed to...most cheap ones last for a year or 2 before they start giving problems...and being in school, he doesn't need to pay 200 bucks every year or 2 on fuel pumps.

$240 is a good price for a pump change for sure.

 

Delphi it is then! Thanks again for all the help.

 

Glad I could.

and glad to hear its gonna be fixed cheap.

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