Governer & Defueling

[Bob Ellithorpe]

What happens when the governer kicks in?? Does the engine start to slow down slowly,misfire or what?

On a recent trip,going up a fairly steep incline with the tach reading somewhere between 2200 - 2400 RPM the engine started to miss with a noticeable lack of power. Later on the downhill side of the incline the power came back on and the engine returned to normal and has run well since,with the exception that several weeks later,it returned to a hard starting situation (hoses have been replaced).

Took the overflow valve out yesterday and it's the non-repairable type. Will order a new one today from Piers.

Here's a tip - when you put rags between the pump and engine to prevent the crush washers from falling - make sure you get the rag under the return pipe otherwise the bottom washer can still slip out when you remove the overflow valve from the banjo fitting.

 

[cumminsgetme]

Check your fuel pressure. Your problem should'nt be governor related. How much fuel was in the tank while traveling up the steep incline? Is it possible that the truck sucked a little air at this point? Your governor simply causes the pump to defuel at higher rpm. There should be no misfire. As rpm increases the governor fly-weights expand and compress against the springs more and more, allowing for less rack travel, thus defueling.

 

[Bob Ellithorpe]

The fuel tank was at least 1/2 full.

By a misfire,I don't mean a backfire(don't know if a diesel can do that ). Engine ran rough and vibrated then cleared up upon descending grade

 

[Joe G.]

Bob,



When my '95 hits the governor is just seems to get kind of gutless. It's still smooth, just doesn't want to go any faster.

 

[HoleshotHolset]

Seeing as you mentioned a pop or a misfire type sound... my vote is for timing... my truck pops/farts and has no sack when this happens.

It used to do it more when I first bought it at the RPM's you mentioned..... now with a few Italian tune-ups under its belt, it's doing it a lot less. Not to mention the weather is different... .



Matt

 

[RHARVEY]

I had a lit pump replaced at Mid-South Cummins in L. R. Ark. back in early summer. When the mech. had finished with the install and also replacing the filter, he started it and after it was running fine(air in the lines from the filter change),he stuck his foot to the floor! At that point is started to miss. . or what I would call a miss as he floored it. I ask about that and the mech. told me that on a cold engine you can tell if the injector pump is starting to wear a little. He said as time goes on. . it could do it when its warm and under load. . He said that it changes the timing because of the wear. So far she pulls great...



Rick

 

[illflem]

My 2500 did the exact same thing for three years and many warranty trips to the dealer, no luck. Only happened going uphill with half a tank or less. On a couple of long hills it wouldn't start again, had to be towed, once on flat land it started right up and ran fine. It was very hard to duplicate this problem, it didn't always do it but when it did it was usually on a mountain pass covered with snow and no place to pull over. I finally resorted to keeping the tank at least half full until a bus mechanic friend figured it out, a self tapping screw in the fuel tank module had worn a hole in the pickup tube half way up allowing it to suck air with a low tank. New module under warranty fixed it right up. Dealer had never heard of this problem.