shuts down while driving, then starts right back up.

[DaveS]

Any ideas? In the past I have had a similiar issue and put a new harness from key switch on and it seemed to have solved problem (1 1/2 yrs ago.) But truck will start and run but especially going up hills or if I step on the pedal it hesitates and not always but more often now it shuts down. After coming to a stop it will restart and idle but usually have to limp it home. Trying to solve problem I just changed the fuel filter, but it really did not help the issue.

1995 chev. 6.5 turbo diesel
230 k - 100k on engine.

[grancito]

Sounds like the fuel lift pump is not working.

[DaveS]

Where do I find the lift pump?, is it easy to replace? How much should I expect to spend if I do it myself? Thanks

[M123KT-450]

Replace your lift pump, change out the fuel filter as well tho i think its part of the pump warranty requirements, other thing i would suggest is how old and where is your PMD located ?

The Lift pump will be located right under your drivers side door on the inside of the frame rail it will look like a GM-Gasser's Fuel filter only it'll have wires coming out of it ;) IIRC 1 wire is brown and the other wire is black but don't quote me :cool: . . .


If you need or want i can post up a photo of the pump ?


Mike

[grancito]

Most likely the oil pressure sensor that makes the pump run. I had it fail on the road and connected a wire from the fuse on the passeger side of the fire wall, behind the plasic cover, to a live wire in the wiper plug. Pump runs when the ignition is on, can stay like that, OPS system is only safety shut off of the lift pump in case of a wreck.

[M123KT-450]

Yes this is true it can be bypassed :D i have mine on a high amp switch, tho i have found the truck will run several mile with out the LP running :o

I forgot to fli it on one time i drove it a good 5 miles before i noticed it was off, So I'm guessing it'll run with out it ? :confused: ?

Maybe it was fluke and i got lucky . . .


Mike

[grancito]

If there are no air leaks in the system, it will run without a lift pump, mine did for a few hundred miles until I realized what was causing the hicup on hard acceleration.

[M123KT-450]

Well then that must be good sign then :D

Mike

[DaveS]

Yes, thanks for the info on finding the lift pump. As I was reading the other posts, it reminded me that the truck runs for about five miles before the truck starts acting up. Is that an indication of lift pump failure?
So I should: replace lift pump first.
fuel filter was just replaced two days ago.
*the pmd- thats the box mounted on the intake- its still in the original spot

[JD_countryboy]

did you ever replace the ops? The drive it a few miles then hiccup is what my truck did when the ops was dead. its a few $ cheaper too. I hot wired my lift pump ( had 12 volts to pump but bad ops contacts wouldnt let enough current thru it to operate lift pump)after replacing it and finding out the ops was junk. Wish id have seen that gm bullitin on that conditiuon before replacing the $80 lift pump.

[M123KT-450]

Yes, thanks for the info on finding the lift pump. As I was reading the other posts, it reminded me that the truck runs for about five miles before the truck starts acting up. Is that an indication of lift pump failure?
So I should: replace lift pump first.
fuel filter was just replaced two days ago.
*the pmd- thats the box mounted on the intake- its still in the original spot

A failing PMD also causes the same symptoms :(

Mike

[grancito]

Open the air bleed on the fuel filter to see if fuel comes out, that tells you if the lift pump is working.

[DaveS]

so if I open the bleeder up and fuel comes out, it would indicate both the fuel lift pump and the oil pump sensor are working properly? Then the culprit would probably be the pmd correct, or can I make that assumption?

[grancito]

Make the fuel test after a run to make sure the oil is hot, the OPS can fail sometimes only when the oil is hot. If your PMD is mounted on the intake manifold, it is the next most likely problem.

[DaveS]

Went to the store and bought both the ops and lift pump. Installed the ops first and problem is solved. thanks to all who contributed to the discussion. Again, thanks eversomuch! Back on the road again.......

[M123KT-450]

Coolness great to hear, tho I would be looking into a PMD along with a cooler/relocator kit and move it outside of the engine bay.
Mounting it behind the bumper is what most do I was skeptical but I mounted my third PMD behind the bumper and it quit failing !

Anywho great to hear your rolling again !


Mike

[DaveS]

I keep hearing about moving the pmd. Is hard to do? How much does it cost? I'm thinking if I've got 230K on it now and it hasn't happened how important is it? any opinions?

[grancito]

PMD failure is the most common problem with these vehicles, if you are handy with a soldering iron and have the PMD mounted already on a heat sink, it is easy to extend the wires and put it in the bumper, costs almost nothing.

[JD_countryboy]

If your not handy with a soldering iron, you can find premade extension harnesses for around $40.

[M123KT-450]

:( I'm poor so i made my own extension cable :o


Mike

[trukdoc]

...heat per se in engine bay it's a thing called "hot soak" you know the thing that use to make that old 62 chev you had vapor lock...if you run up hot and heavy and overloaded and shut it down without letting it set and cool down for 4 or 5 minutes,you are eventually going to fry a pmd...pmds' are a very small percentage of repairs for 6.5s...more common are starter/elec.problems or cooling system problems pre 97 when factory started to install h.o.w/pumps...that said ,if you have a very hi milage unit,it probably wouldn't hurt to shop and stash a pmd cooler assembly....I love my 93 mechanical pump....jd