1999 z56 starts and stall

[99z56]

to start off I was a member of the forum a good while back and cant seem to get back into my account , so here I am with a new one . was hoping you guys could help me with an issue I am having

I have a 1999 z56 ppv Tahoe with 62k truck ran great and had a small lower intake antifreeze leak which I have replaced here where it gets interesting

reassemble intake and start truck , runs without a hiccup for over an hour , reach in the window shut the key off and now it starts and stalls ever since

truck will start everytime and stall , for the times it runs a few seconds longer it runs smooth

truck will keep running on starting fluid
-verify fuel pressure 60 psi at rail
- no secutiry light on dash ( I believe it doesn't have passlock)
-replace distributor due to cracked mounting screw area ( original problem started with original distributor and still persist with new one) verify correct installiion of distributor with timing mark on crank and checked with timing light at cranking speed - dead on
-original spider unit fails injector balance test - replace with upgraded spider
same problem
-replace fuel pump thinking it cant keep up with demand when engine is running - no change - fuel filter is new
- has map sensor code (p0108) test wiring and sensor with mighty vac voltages all check out , replace sensor with new acdeloc map sensor for shit and giggles no change
- cluster is registering rpm and oil pressure
- smoke out intake with professional smoke machine - nothing found
- cannot overcome stalling with pedal so I don't expect vacuum issue
at this point I am stuck , any help is appreciated
forgot to mention I am a full time mechanic for local police department and well versed , I think I must be flustered and over looking something , always have an open mind to learn something new!

 

[Danny3737]

If it keeps running with the starting fluid, you definitely have a fuel delivery problem. I’m going out on a limb, but did you open the door when you shut it off the first time or just reach through the window. I’m wondering if maybe you have an anti-theft device that is shutting the vehicle off. I’m not sure how ours works, but I did have a co-worker years ago that had the same problem in his Cherokee and had to go through some sequence with his key to resolve it. Good Luck!

 

[99z56]

i reached through the window , there is definately no aftermarket antitheft system , I am 99.9% sure there is no factory theft system I also have all old repair history for truck it is still actually used as a department vehicle only for utility purposes

 

[Bear77]

Did you check the fuel pressure after replacing the pump? Had a similar problem and replaced fuel filter and then later the pump. Still wouldn’t start. So I ended up changing the spider as well with no luck. Went and checked the injector wiring and all. For some odd reason, I rechecked the fuel pressure just for giggles and that ended up my problem. Just because you got a new or remanufactured pump, doesn’t mean it was a good part.


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[drakon543]

so just because the way your worded it im going to mention it but im kinda at a loss as to your problem. regardless of what your doing a timing light is pointless on this engine. if i recall the only point you would actually see 0° of timing is at 2000 rpms. below or above that the timing is adjusted by the computer. if your close enough to not be getting a p1345 code it should run. if your far enough out that its starting but stalling due to the distributor being out you should have the p1345 code. so im unsure of your exact problem but if you timed it with a timing light you may have to tweek it once you get it running.

 

[99z56]

timing light used at cranking speed only to verify firing on cylinder 1 at correct time , truck is running now found loss of voltage in run position, found problem with wire underneath fuse block for fuel pump relay

 

[drakon543]

timing light used at cranking speed only to verify firing on cylinder 1 at correct time , truck is running now found loss of voltage in run position, found problem with wire underneath fuse block for fuel pump relay

ahh gotcha good find

 

[Bear77]

timing light used at cranking speed only to verify firing on cylinder 1 at correct time , truck is running now found loss of voltage in run position, found problem with wire underneath fuse block for fuel pump relay

Glad you updated this with the fix


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