M931a Fuel Issue

[TURKEY131]

I tried replacing the seals once and I guess it did not work. Is there specific o-rings that I must use?

 

[TURKEY131]

Well I replaced the seals in the handpump and no more leaking. So that is fixed. Now same end result, no motor start no white smoke. I again disconnected the hard fuel line coming out of fuel cut off solenoid. I am still not getting any fuel out of it. I know I have fuel up to the injection pump. Any ideas on where to go next?

 

[TURKEY131]

Update, I was talking with a gentleman that has been working on diesels for some time and explained to him my problem. He suggested disconnecting the main fuel line going into the injector pump and priming the system. So if the motor starts its an issue with the fuel system pulling air in somewhere. If not its the injector pump. So yesterday I gave it a try and no start, so looks like I am going to be replacing the pump. Anyone else have any input on this or should I check something else first?

 

[wrenchturner6238]

It sure can not hurt to pull the pump and see if things are turning. Once you take off the pump turn the shaft to see how it feels. I have not read back through the hole thread again; before you take off the pump take the fuel solenoid off and leave all else hooked up and crank over the engine and see if fuel pumps out of the pump where the solenoid was.

 

[Jeepsinker]

It is hard to kill those old pumps. I'm still betting on something else.

 

[TURKEY131]

Wrenchturner, I will give that a try before I pull the pump off. Jeepsinker I have pretty much tried everything. I might have a little time tomorrow to work on the truck.

 

[TURKEY131]

Well I finally got around to working on the truck again. I removed the fuel shut off solenoid and had no fuel coming out of the top of the pump. So I then went and changed the injection pump. I really thought that it was going to be a much harder job than it was. After about an hour and a half I had the truck running again! It still runs a little rough though. So I think I might be getting air in the fuel line. Does anyone know of a good place to get the old injection pump rebuilt? Thanks

 

[WillWagner]

Are there any truck shops near you, like Peterbilt, KW, Mack, etc? They will know where to take the pump for repair.

 

[dadsoldtruck]

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[joesco]

Here is my M931 solution..... http://www.steelsoldiers.com/showth...ersion-or-am-I-being-to-simplistic&highlight=

 

[TURKEY131]

Thanks for the replys. I think I going to pull the pumps in the tanks first and see if the pumps are clogged.

 

[joesco]

There are no pumps in the tanks, just pickup tubes which are also problematic!

 

[TURKEY131]

Joescom thanks 5 tons are still a little new to me. So can the pickup tubes be cleaned?

 

[joesco]

Yes and other owners have found the tops of tubes cracked, cause air to be sucked into the fuel system.

 

[TURKEY131]

Ok thanks so the easiest thing to do is to open the tops of the tanks?

 

[allie]

I also have a m931 that all of a sudden is stalling. Runs for about 10 min then just stalls and wont start again until i wait a few minutes.

 

[wrenchturner6238]

allie
You may want to turn in the fuel screw on the fuel solenoid and see if it will stay running. If it does stay running you may have a electrical connection problem or a solenoid hat gets warm and quits.

 

[Jeepsinker]

Replace all of the soft fuel lines. That should be the first thing you do when you have stalling issues with these trucks.
If it isn't sucking air, then that means the shutdown solenoid is faulty and must be removed (8.3L), or replaced (nhc250).

 

[allie]

I will try that. Where exactly canny find that.

 

[wrenchturner6238]

If you are wanting to know where the fuel screw is I have circled it. You will want to screw it in till it bottoms out don't get to rough with it though and after it is in run the truck and see if it helped to shut off truck screw it back out.