Engine revving up at idle

[Plowboy81]

Just had my new engine and rebuilt injectors put in at 5000 miles ago and now its acting up again. It has started at idel to rev up like someone is pushing the pedel. Just does it for a second, but 3 or four times in a row. It even does it when you start it up. Replaced fuel filter yesterday thinking got some bad fuel and treated the tank, even bleed the fuel bowel. Still doing it. Runs fine when driving have not notice any time that it does it then. Thinking bad injector pump, accelerator or my new pdm is faulty.

[DmaxMaverick]

Not likely the PMD or pedal assy (APP, which will cause DTC's and the STS lamp). Probably something simple, like an air leak in the fuel line somewhere. Look for external fuel leaks, to start with.

[Plowboy81]

Looked around today and did not see any fuel leaks. Runs fine when it was cold. Drove it to town about 10 miles and was setting at red light and it started doing it again. Pulled over looked under the hood and still no signs of a fuel leak. I did notice that one of the return lines off the pump looked like it was pinched hafeway. Was wondering if that pinched return line or the leftpump can cause this. Thinking now should have rebuilt the injector pump.

[racer55]

How high does it rev.
Do you have a D-TECH pmd.

[Yukon6.2]

Hi How old is the PMD?
Sounds like a PMD failing,try a different one and see if it cures it.My Brothers truck was doing the same thing,New PMD cured it.
Good Luck

[Plowboy81]

Its the new still pmd, got the two short screws in the front I think it is a D-tech. I put it on the truck back in febuary. I mounted it on a cooler on the upper intake.

[racer55]

Its the new still pmd, got the two short screws in the front I think it is a D-tech. I put it on the truck back in febuary. I mounted it on a cooler on the upper intake.
Its the PMD failing in my opinion.
You should get a PMD extension cable from a site vendor and move the cooler and pmd out to behind the frt bumper or behind the grill and replace the IP harness ground back to the Optical Sensor screw on top of the injection pump where it was originaly attatched to if it had been directed to move it to the cooler.

From most reports I have noticed that the stanadyne pmd's when properly relocated and attatched to a heatsink are more reliable,lately there have been a lot of Dtech failures reported.

[Yukon6.2]

Hi
I had a Dtech fail after very little use,i belive it was bad right out of the box.Try a know good PMD to rule it out.I spent quite a few hours chasing ghosts,when a quick change of a PMD would have ruled it out,or in this case showed it was bad.I was fooled twice in 6 months thinking a new part was OK,when it turned out to be at fault.
Good Luck
Thomas

[Plowboy81]

Well try a new pmd, have to order it no one around here stocks them and let everyone know if it sloves problem. Was wondering if mounting it in the cab is better then in front grill. Virginia uses alot of road salt.

[racer55]

The pmd should not be affected by salt since its weather proof,the wire in the extension harness might be another matter if you don't get one from a reputable source.
The weather pack connectors are the same type used by the lift pump and I can't think of a harsher area for something to be than where the lift pump is and they survive well.

As for mounting in the cab I would discourage that because the pmd is subject to higher temp swings than out in the front area.
In winter it will be heated and then face the cold when the truck shuts down and in summer it might see A/C and then high heat if the windows are up after shutdown.
Outside behind the grill or bumper the pmd will stay at or very near ambient temps,no or nearly no temp swings.

[Plowboy81]

Sorry for the long awaited reply been crazzy over here. Replaced the pmd with another new one that they gave my under warranty and the problem stopped. Waiting to get a day to add on the new add on harness. Whats the best way to mount my cooler and pmd on the front bumper without drilling trought it

[Robyn]

One of my favorite places to mount the PMD is on the inside of the swingdown plate that is right below the radiator area.

Just remove the two bolts back at the front edge of the frame below the engine and swing the plate down on the two hinge bolts.

Snake your extension cable down into the area and then mount the cooler to the inside of the plate.

Hook it all up, swing the plate back up and fasten it and your set.

Had my 94 Burb done this way and never had any issues.

I also carried another cooler with a "Good PMD" that I could plug in and toss on the engine to get home in case of a failure.

Never needed it.

Any of the places that seem to work well are not easily accessed on a rainy cold night, especially if your in your good clothes :eek:

Good luck


Missy

[Plowboy81]

Thanks for that. Have to put that swing down plate back on mine. It was removed when put brush guard on.