M915A1 not fueling properly

[91W350]

We have a Cummins 400 that starts right up and makes no power. When the pedal is floored, the engine does not respond.

After warming up for 15 to 20 minutes, it will accelerate, but very, very slowly. The truck will run 55, but it takes two or three miles to get there. I drove it about 100 miles last Sunday and it seemed to improve with use, but the next morning, back to just idling.

It is also very slow to decelerate, which is very dangerous. The thing might take a mile to come down from 55. I could always kick it in neutral.

I am hoping there is a sticking governor of some sort, like the Multifuels have, if somebody in the know can steer me in the right direction.

It starts within a few revolutions and goes immediately to a smooth idle, I do not believe it to be drawing any air. Thanks, Glen

 

[212sparky]

Is it wet stacked and just needs some good hard runs?

 

[91W350]

Not wet stacked, it is not getting fuel, it never labors to run.

 

[cornrichard]

There is a governor in the PT pump. It senses boost and will not let the pump push fuel until there is enough pressure. It is called the aneroid. I do not think it would cause the truck to not slow but it could if it was sticking. I think you are looking at a rebuild on the PT. pump.

 

[91W350]

If that is the case, we are probably looking at a parts truck. We need some small parts for another 915 and this cab has some rust issues. Thanks, Glen

 

[Ferroequinologist]

Glen, I'm coming out that way in a few weeks, I really need a M915 bumper, tank, and battery box brackets, if you decide to part that truck out.

 

[NDT]

If that is the case, we are probably looking at a parts truck. We need some small parts for another 915 and this cab has some rust issues. Thanks, Glen

The PT pump costs about $400 to rebuild and an hour to remove. Then you have a $5000 truck again.

 

[73m819]

Sounds like your sucking AIR, when it heats up the air suck spot closes a bit, hence the build up of rpm, the slow drop in rpm also is a sign that your sucking air, the cummins does not like air/fuel mix BEFORE the cylinders

 

[StreetbikeDepot]

Check for a stuck aneroid (AFC) or a leak on the boost signal line going to it.

 

[Warthog]

Hey Corey, glad to see you online.

 

[Warthog]

Glen if you do part it out, M1075 may need the hood.

 

[Ferroequinologist]

Mine was acting pretty much the same- believe it or not, it was a plastic plug, in the fuel tank, that would block the suction line. At least I think that was it, I saw it in there, pulled it out, and haven't had an issue since.

 

[dezert ratt]

my 818 was doing similar things, and got worse over time. spent 2 hours going thru the rubber fuel lines, and found one with a pin hole. amazing how it runs so good now.

 

[rangereter]

To test for air in fuel, (slow/sluggish throttle response condition) put a clean fuel line from the PT pump inlet into a clean 5 gal fuel container of fuel, ensure that you have at least 5 gallons return space in tanks, run the engine, and before you run the aux. fuel source empty you have a "snappy" throttle again, then you are pulling air between the pump and your tanks (fuel filters, T connect, tank pickup tubes, etc.)

 

[dezert ratt]

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