i have a 99 3500 dually with a 5 speed tranny. throttle revs up on its own, when it acts up i push on throttle and sometimes it sticks at 4 grand and blows out alot of black smoke. it runs smooth going down the road but sometimes it revs on it own going down the road at high speeds and low.

ip is2 years old,pmd relocated and replace 1 year ago, new glow plugs,filter housing,lift pump 2 years old,ff new. anyone have any ides?? thanks

 

Sounds like a PMD too me

 

ok thanks! time to go shopping. can you recommend a brand? i understand stanodyne is only rated for 185 degrees. is this true? this is the 2nd one i have put on since i have owned this truck. i have it relocated with the heat sink on the top of the intake.

 

I put a new PMD about a year ago on top of the intake and it went bad a week or so ago during a heat wave we had here I just finished relocating my new pmd behind the front bumper this morning I purchased one from these guys along with a extension harness Diesel Care and Performance Inc Oh and they offered free shipping

 

did the pmd fix your problem?. my truck does the same thing but i tried a brand new pmd on it and it didnt help at all so im still searching for the issue. im on my second tranny and the problem is still there.

 

96dually is the truck hard to start is it stuttering????

 

it doesnt stumble at all when it is running.it has been hard to start lately. this truck is backwards of a normal deisel because the colder it is outside the better it starts. itstarts great in the winter but takes 4 or 5 trys in the summer with a fair bit of black smoke almostlike it is overfueling. sometimes helps if i holf the fuel pedal down

 

Dually it may be a long shot but I think I would replace the CPS with a new AC/DELCO dont use the BWD brand as these are inferior products as I am speaking from experence

 

Your problem may be the throtte assembly itself replace the pedal assembly witha used one and see what happens theyre pretty common failures on 94+ also if you relocate pmd relocate it in the grill because if its mounted in the bumper the pmd will not have adequate airflow to help cool at speeds less than 20mph.

 

Did you put the PMD on a heatsink with heat transfer paste/pad?
Did you install a resistor in the PMD?
Have you checked for trouble codes?
Could be a problem with the optical sensor electronic filter,the CPS as mentioned,the timing stepper motor comes to mind as well.