7.3 IDI Driver needs some help

[fx4wannabe]

I am posting this for a fellow member of Ford Truck World. He's not getting any useful info there so here goes:

I have a 1991 f250 4x4 with the 7.3 non turbo and i have a prolbem with it and i want to see if anybody can help??

The problem is when you are goin down the road around 30-50 mph the motor just seems to die then come right back to life in a split sec. I have tryed changin the fuel filter checked for leaks to see if it was gettin air so i took it took a mechanic up the road and he put it on a computer and told me to try to change the throttle position sensor so i did that and still not fixing it so if somebody out there has had this prolbem or have and ideas PLEASE HELP!!!!!!

Thanks

 

[Mr_Roboto]

LMAO. What A$$hole of a mechanic is going to put an IDI on a computer?

The IDI engines are not computer controlled. The TPS is for the transmission only. The only "electronic" part of an IDI engine itself is the Fuel Shutoff Solenoid.

The only thing that will shut off the diesel is "lack of fuel". Since it shuts off mementarily and then everything is fine, you should check the FSS connector on the top of the IP to see if it is loose or corroded. It would also be possible for the FSS coil itself to be failing and causing the FSS to close momentarily.

 

[Exekiel69]

It could also be the lift pump or something on the tank pick-up you mentioned this happens when he drives down hill.

 

[EvergreenRanch]

yeah......i had almost the exact same though as roboto ("what @&*hole mechanic....) as i was reading and then really laughed when i saw he had said it. while i agree with the FSS diagnosis....i htink a little more info would be helpful......what frequency does this occur? every few minutes, once a week....etc......when does it do it (all the time, only on cold mornings after a full moon, etc)....what happens with RPM's, is it full loss of everything (power steering, cab electornics, etc) does he have an idler pully or an AC delete setup.......

 

[hoodshauler]

how old is the IP pump ?Could be time for a pump, the cam on the side of the pump could be worn. I was having the same type of problem with mine a couple of years ago and found that the cam on the side of the IP was causing it.

 

[jeffgordon24]

the tps is for transmission only ! you could have a problem with your injection pump if filter is good or mechanical pump not pumping enough.you can try and tap a guage in between the 2 pumps ,and verify the pressure.does it seem to do it more when you are forcing or going up hill or cruising