So I've been battling this stupid truck for a while now and I am out of ideas! I've read every thread I could find related to my symptoms but nothing is exactly the same as mine that I could find and so far I've had no luck making this thing run.

Problem started with a couple really hard starts and then no start. Did a fuel pressure test and it was only at about 55 psi with key on and quick leak down so I swapped in a new pump (twice)and filter and still no start and leak down so I figured it's either spider or regulator. I picked up a used "new style" spider as I'm planning to do a motor swap and didn't want to spend the money for new. Swapped it in and it started right up and ran great for an hour. Shut it off and back on several times no issues come back out the next day and again crank and no start. I finally got it to work and pulled everything apart drained out the fuel from the spider put it all back together and it started right up but had a cylinder 5 misfire not related to spark so I figured the spider was bad. Again started and shut off several times without issue until I tried to start it the next morning and again crank and no start.

I did find that my fuel pressure issues were being caused by my tester having a crack in the hose so I don't believe the fuel pressure is the issue

Fast forward a bit and I bit the bullet and bought a new ac Delco spider and installed it and started right up and ran perfect no misfire or anything. Started and shut off several times again without issue drive it home and around a bit (30 miles or so) again started and stopped several times without issue and then about 45 minutes later back to crank and no start! I talked to a mechanic buddy and he said try the icm (which from reading made sense) so I replaced it with no change in the condition. I did find that one of the dizzy cap hold down screws was broken so I bought and installed the doorman plate to correct that thinking maybe that could have been the issue but it wasn't.

It has started and ran the 3 or 4 times I've taken the spider out and put it back in but will not restart after it sits for more than just a few minutes.

I've checked all connections and they all appear to be fine. Short of a proper scam tool I'm not sure I can do much else to try and figure out what's going on with it. As of right now it will not restart and just cranks strong but without the presence of fuel. It will fire over and run when I put fuel in the intake. It seems like a fuel issue but every component of the fuel system is new a.c. Delco parts. Any ideas?

 

That really sucks Rex. Just a mostly amateur suggestion here, but how is the battery? Does putting the truck on a charger to maintain steady high voltage make any difference? When I was having starting problems a couple years ago my dying battery was contributing to the issue and complicated the troubleshooting.


I'm sure Captain Hook or Swartlkk will chime in here. They're the serious Guru's with troubleshooting.


Good luck!

 

Yeah I had my battery charged overnight at advanced so out had good cranking power. I'm hoping they chime in lol!

 

If it starts when adding fuel, it's a fuel delivery problem, no doubt. Couple things to try: While it's acting up, connect the pressure tester and cycle the ignition while watching the pressure tester needle. The needle needs to deflect immediately when you cycle the pump on. Try it several times and listen carefully to the sound of the pump each time. I've had a few pumps start up instantly, but didn't build pressure instantly, as it must do. After a couple of seconds of running, the pump motor would change pitch, and it would start building pressure. Just because the pump makes noise, doesn't necessarily mean it's building pressure.


Another possibility is a poor/loose ground for the pump. Could be the same issue with the power feed for the relay and or wiring to the pump.

 

Alright I'll have to go over the fuel system again with a new pressure gauge and see what happens I guess. I'll get a new gauge tomorrow and post up what I find.

 

Ok so I bought a brand new tester and with key on it hits 62-63 psi then drops to about 58 when the pump stops and after 10 minutes it was sitting at 55-56 psi. Did this 3 times and same results each time.


The one weird thing I did notice that I had not before is that when cycling the key on and off I would occasionally have to turn the key a touch past the "run" position almost to the point of engaging the starter to get the pump to turn on but then it would immediately jump to the 62-63 psi range. Could the ignition switch be the culprit?


Is it possible to have some air in the spider causing a vapor lock situation? I ask this because the times that I removed the spider and tipped it upside down to drain the fuel and then reinstalled it would start right back up until I let it sit for a while. It did this twice with the old "new style" spider and once with the current brand new spider.


I'm just at a loss since it seems to have spark and fuel but it doesn't seem to have spark and fuel together!

 

Key-on/pump off pressures and leak down are exactly like mine after I replaced the spider with a brand new AC/Delco one. Mine has never had anything but instantaneous starts (just bearing problems!).

What is the fuel pressure during your no-start cranking? With the new-style spider, it should deliver fuel if injectors are getting the correct pulses (a min pressure is not required for these injectors to open). If pressure is anywhere near 50-60psi and you have a no-start due to lack of fuel (you have already verified this by adding fuel and vehicle starts), I would suspect the injectors are simply not getting the pulses required to open them. Problem seems electrical and centered in fuel injector control to me, based on what you have told us. I'm sure the Captain has a good way to probe an injector circuit and test this.

 

That's exactly what I am leaning towards now myself is injector pulse or related issues! Guess its time to start reading again

 

In the past I have seen internally shorted injectors cause PCMs to shut down (to protect themselves). This was in older GM TBI and PFI systems. Although you have eliminated the injectors themselves as a potential cause by replacing them, might you have a wire intermittently shorted to ground somewhere in the injector control circuit that causes the PCM to freak out and protect itself? Always seems to start great for a while after removing the big injector connector and manipulating the harness.

 

I'm going to borrow the shop next door to mine's Solus scanner tomorrow so hopefully that will give me some clues add to what night be going on. I also printed off swartlkk's 30 something diagnostic flow chart so if the scanner doesn't reveal anything I guess I'll start on the list and work my way through it to see what's going on!