My truck is broke down in a parking lot as we speak. I started having trouble with it cranking back in Nov. after I got stuck and had to leave it stuck over night. Ever since then the problem has been intermidant, but at some point the truck always cranked wether it was the first or the 20th try. Well, today it just stopped. The truck cranked as usaul and as I put it in drive, it spuddered and died. It hasn't cranked since. I have good, but high fuel pressure at the schrader valve, about 80psi. I also have good spark. For some reason, it just isn't cranking. Any idea's?

 

Good air, good fuel, good spark. Only leaves timing, possibly cam/crank sensors. Just a guess though....

Ryan

 

That's what I'm thinking. I'm going to swap the Crank Position sensors first thing tommorow. I don't believe 97's had a cam sensor.

 

your truck has a cam position sensor along with a crank position. The crank position sensor is mounted in the front timing cover, the cam position sensor is in the distributor. Your problem sounds wierd, is your fuel system stock? 80psi of fuel pressure is extremly high espicially if you still have the poppets. I would almost think you are having a problem with the pressure regulator and your engine is flooding out. I think that is what's causing your problem. At 80 psi if your running the poppets they will begin to let fuel bleed through them not to mention the pcm problems it will have from such a high pressure. I think your having a flooding problem which is related to a problem with the regulator or restricted return line

 

The only thing is, there is no fuel in the cylinder. The plugs are a dry as they can be.........

 

Hmmm... well than that sounds like the pcm isn't firing the injectors. Have you tried putting a scanner on it to see whats goin on? also have you tried pulling any codes? You might also want to check the ecm fuses. Putting a scan tool on there would definately help pin point the problem a lot quicker

 

I just put the auto tap on it, but it didn't reveal anything. It dosen't show much in the fuel area. What you stated has become my conclusion. The injectors are not firing. Now what causes them not to fire, I have no idea. I've pulled every fuse I could find and they were all ok. I hope it isn't a bad ECM........

 

I haven't actually ever tried this well cranking but i think it might work. I would measure the injector pulsewidth and see what its at. I would think if it's at 0 then the pcm isn't getting any signal to fire the injector from other sensors which would make me think crank sensor. Its really hard to say and i wish i could give you a answer that isn't just throwing parts at it. The 80psi of fuel pressure still worries me also.

 

I finally figured something out, but it still dosen't help. I've changed every sensor imaginable, for free of course, but nothing lets the trunk crank. On to the wierd part. If I put a cup of gas down the TB, the truck will crank and run fine. When I kill it, it will not re-start. For some reason, it is needing gas to prime it off and I'm not sure why.

 

have almost same problem 96 GMC 5.0 vortech
has FIRE,FUEL,AIR FLOW and will start will run UNTIL u hit the gas, then starts 2 misfire and pop then stalls ANYBODY HAVE ANY IDEA???????? iam thinking timming???