97 gmc extremely intermittent no spark

hey guys, question on my 97 vortec 5.7...truck randomly started dying about a month ago. thought it was a fuel issue so 1st changed pump relay. fine for a day or so then died again...long story short changed pump and sending unit still same problem...after some checking found a no spark issue when it dies, so new crank sensor, cam sensor, map, tps, iac,coil, finally distributor. still random dying w no spark...if my temp sensor in the d.s. head is bad, would that cause no spark? thanks in advance

Have you tried checking for codes yet? That's what I would try first.

Doughnuts said:

Have you tried checking for codes yet? That's what I would try first.

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getting a code for cam/crank correlation, but I've had that code for over a year when I put a crate longblock in it. never hooked it up to a tech 2 for timing, but she's ran great all that time...this is in the last month or 2

Broken / bad cable . Battery to starter / battery to ground. Amazing number of these run badly or not at all and it turns out to be a corroded or broken cable. The key is the intermittent symptoms. That is almost certainly a bad electrical connection somewhere.

Make sure and report back to the thread when you figure out what it is.

Eveready said:

Broken / bad cable . Battery to starter / battery to ground. Amazing number of these run badly or not at all and it turns out to be a corroded or broken cable. The key is the intermittent symptoms. That is almost certainly a bad electrical connection somewhere.

Make sure and report back to the thread when you figure out what it is.

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I agree. I'd check cables. Particularly the coil cables, crank position sensor cables, etc.
Out of curiosity, how did you confirm no spark? Manually/visually? Where?

Going through something simular , except that my local dealership cant event get it to run . I have narrowed it down to the passlock failing . My security light does not light up at all . I have replaced the following , and the tech says that the truck is timed , but still does not run .
Fuel pump relay , fuel pump , strainer , filter , spider injection , oil/ fuel pressure switch, distributor , cam sensor , crank sensor , icm , cap , rotor , plugs , wires , coil , and timing chain .

How about the Ignition Control Module?

Flying Skunks said:

Going through something simular , except that my local dealership cant event get it to run . I have narrowed it down to the passlock failing . My security light does not light up at all . I have replaced the following , and the tech says that the truck is timed , but still does not run .
Fuel pump relay , fuel pump , strainer , filter , spider injection , oil/ fuel pressure switch, distributor , cam sensor , crank sensor , icm , cap , rotor , plugs , wires , coil , and timing chain .

Click to expand...

Wow, I’d try another dealership. The manual has diagnostic steps for this...that the security light doesn’t come on should give them a place to start.



The table above has links for yes/no responses, let me know if you need any in particular.






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Flying Skunks said:

Going through something simular , except that my local dealership cant event get it to run . I have narrowed it down to the passlock failing . My security light does not light up at all . I have replaced the following , and the tech says that the truck is timed , but still does not run .
Fuel pump relay , fuel pump , strainer , filter , spider injection , oil/ fuel pressure switch, distributor , cam sensor , crank sensor , icm , cap , rotor , plugs , wires , coil , and timing chain .

Click to expand...

The dealership :

A: Wants to sell you another vehicle.

B: Has a bunch of "parts replacers" and probably no mechanics.

You need to see an old time GM tech who knows his s**t. Some old garage guy near you knows how to fix that pup.

When does it die and what's the behavior of it?
My '97 yukon 5.7 hasn't run completely right ever since I put the engine back in a few months ago. It idles sort of rough and hesitates right off idle, and sometimes it feels like it'll miss once or twice while cruising at low rpm. Some days are worse than others. It's sputtered and died while getting on the gas off idle about 5 times in the 1,000 miles I've put on it. It'll also sometimes surge when stopped in fear with the ac on. That's only on its bad days though.
I have a cam position sensor code. I think the timing isn't set right.
Just wondering if your symptoms are the same.