[jeff power]

Ok been awhile since I posted on here, I got a new truck and am having some problems with it.

Bought a 1997 f350 4x4 auto 7.3 sunday, and on the way home it died and restarted easily twice after stopping at red lights.

Monday I changed the fuel filter and did the DIY Tymar. Immediately after fuel filter change I started the truck and it idled fine for 3 minutes, I rev the engine a few times, sounds good, then all of a sudden it starts to stumble like its fuel starved, and then dies, will not restart.

Tues Morning I crank a few times and it fires right up, runs great for 10 min driving around the block, then stumbles and dies. Cleaned the FPR screen which unbelieveably dirty, with no results. Local mechanic suggests fuel pump, I check the pressure at the FPR valve, no pressure when cranking, but fuel bowl is full. I took the FPR spring and valve out clean and reinsert, truck fires and runs great immediately. I have 20 psi when cranking and almost 70 when idleing.

5 minutes later while Idleing I revved the engine up to 2000 rpm and let off the throttle truck immediately dies and restarts with no problems, I do this several times. If I rev it up to 2000rpm, let off the throttle, it will die, sometimes I can catch it before it dies and bring it back to a normal idle.

hpop is full
unplugged icp no change
truck has 220000 miles on it.

Thoughts? and thanks in advance.

 

[BigFuel]

So it dies upon the desire to idle? Test your Idle Validation Switch (next to the Pedal Position Switch on the go pedal). With a meter set to Ohms scale test the switch from post to post and take a reading. Should be no more than .1 Ohm. Also see what the readings say when you work the switch. Should be a clean .1 Ohm -> OFL -> .1 Ohm.

 

[jeff power]

It stumbles when returning to idle from throttling up for more than a second or 2. It doesnt do it while driving, but then again I havent driven far from the house since I got it.

One thing I did notice is rpm surges up and down at idle, at steady cruising speed or while accelerating. Also sometimes when accelerating it feels like its bogging down while other times it clears up and takes off.

 

[jeff power]

Ok just wanted to close out this thread for those that may be having the same issue.

For me it was the IPR, the old one was so gummed up I had to pry the solenoid off the post.

Changing the Oil did help slightly, I may change it again, because the it was so bad I'd like to make sure all the old oil is out of there.