Engine/Transmission (1994 - 1998) motor has a mind of its own!!

[DISPATCH]

my brothers 97' 12v has a mind of its own you start the truck and it goes to 1k rpm then all of a sudden on its own it ramps to 2500 rpm and back down and up and down and up you get the idea. fuel pressure is good star wheel is set right fuel plate is set right so is the 3k gsk. any other ideas could this be somthing internally on the injection pump or an overflow valve?? it has me and my mechanic stumped on this one.

 

[A-bomb]

Sounds like a govenor problem if the fuel pressures are good. Double check the 3kgs's.

 

[HoleshotHolset]

Sounds like somebody messed with the governor lever... eh, Tom?



Matt

 

[DISPATCH]

checked the gsk twice everything looks good any other ideas??

 

[A-bomb]

Still sounds like a govenor problem. when did the 3kgs get installed? Maybe one of the springs is broken. When you checked the govenor did you do a visual, or did you actualy take them ount and reinstall them? It is very difficult to tell anything by just looking in the little hole. Also take off the AFC and plate and check the fuel control arm.



What was the last thing worked on?

 

[DISPATCH]

last thing worked on was the plate and gsk but it ran good for a few months and then all of a sudden it went wacky ill check the gsk again any other ideas or is this basically it?? thanks for all the imput.

 

[BV]

It's a long shot but maybe your sucking oil from the turbo. It's easy to check by pulling the intake snorkle off the turbo and see if any oil is in there.

 

[HoleshotHolset]

How quickly does the engine oscillate between 1k and 2. 5k RPM?



It almost 'smells' of an intermittent fuel delivery issue...combined with something gone awry in the governor.



After Tom (98Rammer) adjusted his governor lever - something happened afterwards that caused one of the governor spring 'packs' to get bent. His truck didn't oscillate RPM's, though (if I remember correctly... ) - it just stayed at like 1700 RPM all the time...



Tom had a very hard time seeing the problem until he took the governor springs (both packs) right out of the truck. The stud that holds the whole business together on one side was slightly bent causing it to be on permanent high idle.



On edit: I like BV's comment - it's certainly is possible that the engine is running on an intermittently available 'alternative fuel source' such as the engine oil, etc...



Matt

 

[DISPATCH]

about 3 sec pass between the time it starts at 1k and the time it gets to 2500rpm and another 3 sec or so to get back down and then another 3 or so to go back up.

 

[98rammer]

Sounds like somebody messed with the governor lever... eh, Tom?



Matt

noooooo, that would be illegal and unsafe. i would never condone such an act :-laf





yeah, i didn't realize what caused the bent spring set. the nut, lock washer, and small fully threaded screw came out and bent one of the posts that holds the governor spring packs in. this was about 5,000 miles after i did the lever adjustment, oh well, my fault. it started at 1500rpm, but worked it's way up to 1700 on the drive north to maine.



it does sound like a governor problem or some fuel/oil problem.



Tom, guilty as charged

 

[HoleshotHolset]

about 3 sec pass between the time it starts at 1k and the time it gets to 2500rpm and another 3 sec or so to get back down and then another 3 or so to go back up.

That's a really strange one, man... Is the engine eating a lot of oil? Have you checked the fuel lines to see if there might be a chance that it's sucking air? Have you reinstalled the OEM governor springs?

noooooo, that would be illegal and unsafe. i would never condone such an act :-laf

Tom - you make a good point. Govnahs are usually guarded by state troopahs...



Matt

 

[98rammer]

do you think that maybe one of his spring packs are bent (the rod bent a little bit, but not as severe as mine)? maybe the springs are binding, then letting go, binding, letting go. . ?



Tom

 

[Andy Redmond]

I have a pump on my truck that had pieces of plastic pump timing pin in gov. springs that caused your symtoms. They sold it with a new timing pin, then I picked it up from its second owner after it had been to the pump shop to be checked out. Its fun to be the detective when your not the one experiencing the problem.



Other thoughts, has the throttle cable been updated from the open to the shielded design, if not the cable operation may not be binding in the cable sheathing and not engaging and releasing properly.



Also the ball stud /connector on the speed lever (back end of inj. pump) could be binding causing it not to idle down.



Other have offered excellent advice, but maybe you'll get lucky with something simple.



Good luck

Andy

 

[DISPATCH]

turns out the fly wieghts came apart in the injection pump. the truck is back on the road at mere $1200 later thanks for the all the imput!!



drew

 

[HoleshotHolset]

Drew: Thanks for updating us on this issue. How was it eventually fixed? Did 'they' just replace what was bad in the governor section?



Thanks,



Matt

 

[DISPATCH]

the injection pump was sent out to a place in i think in ohio and they bench tested the pump and came to the conclusion that the fly wieghts blew apart im not sure what all they rebuilt on the pump other that that they tweaked the pump i think 12% truck runs good now and blows some smoke :-laf

 

[HoleshotHolset]

Was it Columbus Diesel Supply?