Mabey I posted in the wrong forum yesterday (1st Gen) .
But heres whats up. When I turn the key on but not all the way over, the fuel pump hums as it should but will not stop . If I try to start the truck it just cranks and cranks.. If I turn the key on, off, on ,off, several times, try to start it, wait, ect., the pump will eventually stop humming and the truck will then start up and run fine. This started out as a small problem at first, as it would usually crank up and run after a try or two. But then eventually it just wouldnt start at all. After installing a new used pump, wich was bench tested and pumped ok, Im still having the same issue.
If the truck sits in the sun a while it seems to crank up rather easily. If its a cool morning on the other hand, the pump seems to just never stop humming and the truck wont start. Sorry for the long ramble and a second post, but Im stranded, Im tired , and Im out of ideas.

 

Put a fuel pressure gauge on it. See what pressure looks like.

PCM is supposed to control the fuel pump relay, sounds like it is getting confused.

 

Thanks for responding HeyYou, I drove a friends little toy to work today.. I like the 3500 better. I cant seem to find a valve any where on the rail or motor to test fuel pressure though, but Im about half blind now days so mabey Im missing it. Where is it?
Edit:: Googled it. gauge has to be stuck in between the rail and supply line. No valve on mine.

 

Yours must be a 97......

 

the mfg date on the door says 96, but the engine was replaced last year, so mabey the it came out of a 96?

 

Bottom right of the image

 

What month makes a difference as well. Basically, anything after 7/96 is a 97 model year truck.

 

I hooked a gauge into the fuel line at the rails, and as soon as I turn the key on it hits 50 psi. turn the key over, and as it trys to crank it drops slightly, but it holds between 45 and fifty after the keys off. I was able to start the truck at one point, and at normal operating speed psi also holds at 50. if its the pcm , I cant figure why it doees eventually start after multiple tries sometimes.

 

Would be interesting to see if a scanner could communicate with the PCM when you have your no-start condition.

 

thats an idea. ive heard you wouldnt get any codes if the check engine light isnt on, I wonder if i can talk the guy at auto zone into hookin it up for me any way.