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It's driving me crazy!!

D

DFR

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Nov 2, 2005
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Tennessee
Okay need some help here if possible, let me start from beginning, truck died one day on the way home and found driverside fuel pump was bad, I replaced it and truck ran great for 2 days then died again. I checked pump and it was getting 8 volts at the plug, figuring that fuel selector was bad replaced it, and fuel filter and nothing, would turn over but no fuel, so after reading things through out the internet I replaced fuel selector switch, ignition module, fuel pump relay, injectors, iac valve, ignition switch and battery cables. After disconnecting battery and reconnecting it will no longer even turn over, tried 2 different batteries and nothing, checked voltage on both sides of fuseable link and getting 13 volts both sides. I have even changed oil pressure switch. What am I missing, I can here relay energize, but when I check for voltage out of fire wall to plug that runs to pump nothing, hooked up to scanners and it is communicating with ecm and no codes, this truck only has 120,000 miles on it, and is in great shape other than my existing problem, any help might save me from losing my mind!!
 
A little more info. please, i.e. veh., engine, year, etc. What part of TN are you in?
 
Oops sorry, so wound up over my problem ( I have been fooling with this problem for nearlt 3 weeks) I forgot to post vehicle info, 1987 silverado pick up 4x4, 5.7 liter tbi motor with 4 speed auto, this truck has 2 tanks, and by running hot wire to the pumps they both work and have 1/2 tank fuel in each.
I am located in Jackson about 1 1/2 hours from where you are, actually bought my suspension lift 5 years ago from John Walls in Memphis.
 
I dont recognize the problem....but what codes is it throwing? That could definitely help us out a little but. Also, did your replace the egr and fuel pump??? I know my bad egr made my balzer do some very strange things....and if the fuel pump goes bad...it aint gonna start. Just some suggestions though.
-Harrison
 
thanks for response, but no codes, I am getting no power to or from green wire, and tan wire at relay, pump is new, and have tested them, they run when jumped to 12 volts.
 
First things first you need to figure out why it won't turn over.

By turn over, I'm assuming you mean the starter won't turn the engine over when the key is turned to start.
 
DFR said:
... would turn over but no fuel, so after reading things through out the internet I replaced fuel selector switch, ignition module, fuel pump relay, injectors, iac valve, ignition switch and battery cables. After disconnecting battery and reconnecting it will no longer even turn over, tried 2 different batteries and nothing, checked voltage on both sides of fuseable link and getting 13 volts both sides....QUOTE]

Dorian:
It would seem that his problem has worsened since he dis- & re-connected his battery.
My guess is that he has shorted or blown some other fuse/relay involving the starter circuit while working on battery hook.up.
Maybe new ignition switch is different or wrongly wired.
DFR:
Try puting everything you took off, back on, to at least get engine to crank over?
Click to expand...
 
You might check your neutral safety switch for adjustment or being defective. Don't know if it would contribute to your lack of power to the fuel pump relay but it might be what is keeping it from cranking.
 
I have seen this before. When you replaced the battery, is there a chance you dropped one of the wires down near the battery tray?? I went to help a guy out with this same problem and he swore he put all of the wires back on. A little hand fishing came up with the wire that powered his fuse box.
 
Okay got the motor to crank again, had to replace starter, but still at no start, orange wire at relay hot, but no other wires hot coming out, the green wire that goes to ecm would that keep the relay from closing to complete circuit? the wiring diagram for fuel circuit shows a hot fuel module with three wires, I can't find it, not sure what I am looking for, it will run with gas poured into throttle body, so I think ecm is okay. Or could just one program in ecm gone bad, next step I guess is to reattach all ground and go thru the harness to make sure a wire hasn't shorted out.
 
I just had to test my relay cause I had a no start condition when I replaced the gas tank. I distinctly remember 2 hot wires. One gets power from somewhere, other gets power from computer according to the wiring diagrams. Another thing could be the oil pressure switch. It needs to sense oil pressure in order for your computer to allow the fuel pump to run. It is located above the oil filter. It has a guard on it. I have a pic of it in another thread. Check to make sure that is still connected, functioning, and the signal is getting to the computer.

http://coloradok5.com/forums/showthread.php?t=151035

Good luck man...
 
fuel pump

can you jump a hot wire to the fuel pump to make it work ? if it wont that would probably be the problem .
 
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