5.7L.Starts won't Run

Vetteuser · 08-18-2007, 12:47 PM

97 GMC1500 ex cab 4x4 5.7L.

Salvage vehicle, supposedly was running a while ago,
Dash apart, and steering column loose
Wiring looks hacked or modified in the engine compartment on the big plug beside the TB on the intake manifold, a few red wires appear spliced together with a non stock connector into one as a possible indication something has been bypassed at one time.
Air intake at the TB haywired with a piece of plumbing strapping to stay on and has what looks like a big plumbing plug glued on the side of it secured with screws
Air filter housing bungee corded shut,

Other than that all looks original. In the engine compartment anyway.

Starts, but won't stay running, fuel pump sounds,
Makes 60 psi, looses pressure quickly to 40psi when turned off and half as much less 5-10 minutes later, If that just means the injectors are leaking.
Other clicking noises in the engine compartment start after it quits, IAC or other controls?
Fuel pump also continues to sound but quits soon later.

Will continue to run, a little rough, pouring gas directly down the intake with the air intake housing with Maf unhooked. Which I didn't think would be possible and produce a code, or check engine light, But I don't know anything about OBD2
Didn't have much fuel in it originally so added some,
When the pressure tester was drained looked OK with no water, though a day later may have some slight sediment in it

The speedo cluster was hooked back up, but didn't produce a check engine light, (didn't try it myself) the owner wants to change the steering column, hence it loose. As well as the cluster apart, but it runs when gas is poured down the intake so still maintaining "Run" when the key is released. Applying throttle while trying to start, it won't, presume to be in clear flood mode. Fuel pressure maintains during the process or might haver dropped to 55lbs so one might think the fuel pump is still OK and fuel in it.

Don't have a scan tool so any suggestions?

Thanks in advance.

lefty1953 · 08-23-2007, 06:14 AM

How long did it sit? Might be just some really bad gas. Might try draining it and then putting in some new.

03chevy · 08-23-2007, 07:43 AM

about the wiring sounds like the computer is bad so they tried to bypass it and make it run. so they did all the splicing to bypass it

08-18-2007, 12:47 PM	#1
Vetteuser Junior Member Join Date: Aug 2007 Posts: 1	5.7L.Starts won't Run 97 GMC1500 ex cab 4x4 5.7L. Salvage vehicle, supposedly was running a while ago, Dash apart, and steering column loose Wiring looks hacked or modified in the engine compartment on the big plug beside the TB on the intake manifold, a few red wires appear spliced together with a non stock connector into one as a possible indication something has been bypassed at one time. Air intake at the TB haywired with a piece of plumbing strapping to stay on and has what looks like a big plumbing plug glued on the side of it secured with screws Air filter housing bungee corded shut, Other than that all looks original. In the engine compartment anyway. Starts, but won't stay running, fuel pump sounds, Makes 60 psi, looses pressure quickly to 40psi when turned off and half as much less 5-10 minutes later, If that just means the injectors are leaking. Other clicking noises in the engine compartment start after it quits, IAC or other controls? Fuel pump also continues to sound but quits soon later. Will continue to run, a little rough, pouring gas directly down the intake with the air intake housing with Maf unhooked. Which I didn't think would be possible and produce a code, or check engine light, But I don't know anything about OBD2 Didn't have much fuel in it originally so added some, When the pressure tester was drained looked OK with no water, though a day later may have some slight sediment in it The speedo cluster was hooked back up, but didn't produce a check engine light, (didn't try it myself) the owner wants to change the steering column, hence it loose. As well as the cluster apart, but it runs when gas is poured down the intake so still maintaining "Run" when the key is released. Applying throttle while trying to start, it won't, presume to be in clear flood mode. Fuel pressure maintains during the process or might haver dropped to 55lbs so one might think the fuel pump is still OK and fuel in it. Don't have a scan tool so any suggestions? Thanks in advance.

08-23-2007, 07:43 AM	#3
03chevy Senior Member Join Date: Dec 2006 Location: jax,fl Posts: 1,196	about the wiring sounds like the computer is bad so they tried to bypass it and make it run. so they did all the splicing to bypass it __________________ A dirty mind is a terrible thing to waste!

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08-23-2007, 06:14 AM	#2
lefty1953 Junior Member Join Date: Jul 2007 Location: Colorado Posts: 9	How long did it sit? Might be just some really bad gas. Might try draining it and then putting in some new.