Log truck idle problem

[Dave Shepard]

I have been doing extensive log yard reorganizing with the log truck the past few days. The truck has been driving me crazy. I set the throttle fairly high, but when you run the loader, the engine slows waaaay down. It doesn't sound like it is laboring, just doesn't maintain a very high rpm. I know that trucks don't have governors like a farm tractor, but this thing is really bad. It makes it really slow to operate, and also jerky. Anyone that runs a log truck I would appreciate some input. Does your truck maintain a fairly even rpm? The engine is a Cummins NTC350 that was cobbled in place of a CAT that bought the farm, so who knows what has been done to it. Excessive cobbling by unexperienced people with wrenches is likely. Anyone have Cummins experience that might see a problem? Would a plogged fuel filter or air leak in the fuel line cause this? Thanks.


Dave

[Timburr]

Dave, has this symptom developed progressively?  The first port of remedy is a fuel filter change. If ailment still prevails check fuel lines for air ingression.

The "N" series Cummins has a very robust injection system when properly set up. But, if a wrench wielding novice has been let loose, anything could have happened.

Another thing causing problems could be a faulty ?aneroid?.  This device balances the turbo boost pressure to the fuel metering. When it fails, all sorts of odd engine running characteristics occur!

[Sawyerfortyish]

My old log truck had a 350 cummins I had to have an electric govenor of some sort installed to maintain a steady rpm to use the loader. My new log truck has a 315 cummins with some sort of air operated govener. I have had the same thing happen as you describe twice and both times the trucks fuel filter needed to be changed. The last time I ran it to try to finish the load and maybe limp home but the truck died and wouldn't even try to run until I changed the filter. So hopefully thats what your problem is

[Dave Shepard]

Our "mechanic" is supposed to change the fuel filter tomorrow. He isn't a very cooperative sort of person though, and if I suggest something, he gets bent out of shape. : : : He has been masquerading as a mechanic since before I was born, and I think I know at least twice what he does. >:( Everytime I try to get help on this truck he says it should be scrapped and we should get another one. ??? ??? ??? It might be old, but it isn't too bad for what little we use it.

I'll look into the aneriod, I have heard of those before, but didn't realize they were used on the Cummins PT injection system. If all else fails, I'll call Cummins Northeast, they don't mind talking to you, great company. 8) Thanks.


Dave

[Quartlow]

Governors are set with a certain amount of drop, meaning how far the the rpms drop before the governor kicks in and pulls the throttle open.
Stationary equipment and farm tractors typically have a low percentage of drop. Meaning they only loose a few rpms before the governor try's to recover it. Road engines are set at a higher percentage.

Whether or not it,s adjustable without taking it too Cummins I'm not sure. One things is for certain, when you call Cummins have your CPL number handy, it's on a tag just in front of the accessory drive  on the driver side of the engine. That tells them everything about that engine

[loggersmg]

If I recall correctly, Caterpillar engines use a mechanical governor that closely controls engine rpm whatever the throttle pedal position.  Older Cummins engines NTC series
use an automotive type governor which lets the rpm fluctuate more.

However there is a hi idle governor control available that plumbs into the fuel pump system and is activated by a 12 volt solenoid. You adjust this unit to the rpm you want after installing it and when you apply 12 volts you get the same (constant) rpm while the engine operates under various loads .

Cant Remember the manufacturer but I think I may have an old unit around. if I can find it I'll let you know

[Dave Shepard]

Thanks for the replies! I think one of the other trucks has an electric governor, I think the truck with the rollback on it, it is a Cummins as well. I'll have to check it out.

Welcome, loggersmg!


Dave