Strange problem, wants to die on cold idle

[Alex S]

So laity when the engine is cold and when i lift off the accelerator it dies (if im not rolling) or almost does when its warm there is no problem but when its warming up if it doesn't die the rpm will drop down to like 100 or so and then clime back up to a proper idle rpm all on its own. its very annoying

Everything else seems to be fine above idle rpm, has the same power seems to run the same

Thx

7.3 na with a ZF5

 

[argve]

What's the idle rpms?

Could in the injection pump - try running some fuel lube through it - I always liked Power Service and Stanadyne brands. What I'm referring to in the pump is the metering pump.

 

[Alex S]

ya i gues it is something in the pump :-( i did change the fuel filter and filled it with atf and went for a run so tomorrow will see if there is any difference.

RPM is about 700

 

[LCAM-01XA]

What he said - run engine till warm, shut off, empty filter of fuel, fill filter with Diesel Kleen or SeaFoam or even plain ATF and reinstall, fire up engine and run for 30 seconds then shutoff, let sit for several hours (preferably overnight), then fire up again and hopefully all the evil stuff will get flushed from you IP restoring the proper operation of its low-speed governor thing.

 

[Alex S]

ok ok, so maybe so there is a low speed governing thing that could be sticking?

 

[LCAM-01XA]

Yes yes, there is such a thing, and when it gets gooped up with fuel varnish and deposits (cause filters are only so good after all) it starts acting up like yours is.

 

[Alex S]

is it something i can take the top cover off and take out and clean up?

 

[LCAM-01XA]

That I don't know. The liquid soak and clean method usually seems to work just fine tho...

 

[argve]

is it something i can take the top cover off and take out and clean up?

Nope, not much in there that is serviceable in this regards. About the only thing you can get to is the fuel shut off and timing advance.

 

[starmilt]

Careful with removing the top cover, if installed incorrectly you can have a runaway condition, with no shutoff.
Lcam has it right, but I wouldn't use tranny fluid to soak it in, it may cause a hard start after is sits for awhile. I would use a good diesel additive cleaner, diesel kleen, howes, seafoam, something on that order.

 

[Alex S]

ok well i poured a bottle of seafomein a 1/2 tank of fuel and will see if that helps. But running straight seafome threw the IP pump wont hurt it? it seems more liquid-y then water

 

[Agnem]

Have you been running a lubricity additive on a regular basis, or have you been running just streight #2? If your not running an additive you should be. ALL the time.

 

[LCAM-01XA]

Alex, I've done the seafoam thing in the IP, didn't seem to hurt anything. And Mel is right, we do need the fuel additives...

 

[RLDSL]

If you think you might have something sticking the very best thing to run is about three ( or more, 3 min for an engine this size )cans of Diesel Purge . You have to do a little re plumbing to run that stuff through . You need a length of hose to go from a bottle to the lift pump inlet and another length to go from the return line outlet at the rear of the engine to the bottle ( a 2 liter soda bottle works, or you can use the cans ) attach the hoses and stick the other ends into the bottle and empty all three cans into the bottle , push the inlet line to the bottom, fire up the truck and let it run until it uses all of the Diesel Purge up. The truck will be running on darn near straight diesel purge , if you get a few extra cans and empty the filter and fill it with diesel purge before you start you will have a more concentrated solution . This is a seriously intense fuel system cleaner from Germany where about 60% of the vehicles on the road are diesels. They've figured out some things for everyday diesel problems

 

[Alex S]

ah well thx guys, before reading the last part. Sat i dumped a can of seafome into a 1/2 tank of diesel and rapped it up a long hill WOT and 2000 rpm then went home and let it sit over night. The next day all was back to normal and its running like a top now, throttle response has improves as well