M923 fuel issue

[Scottro]

I just purchased an M 923 about a month ago. It's a 1990 Harsco hard top with fold up troop benches on side of bed. It has a couple of issues. The first is starting, it take a long time for the fuel to prime, the motor has to turn over for a good 30 seconds before the fuel picks up. Once it fires off the throttle response is fine. Or we'll start with a shot of either wich I do not like using. The other issue is the on board internal air system. The tires don't self inflate , when I first drove it , the air pressure popped off around 120psi , now it is running up to 150psi. Anyone have this experience ? Any help would be greatly appreciated.

 

[wrenchturner6238]

I would crank it over and have someone watch to see if the fuel kill solenoid is staying engaged if not that is your problem because you have good throttle and it starts. Then I would remove the fuel filter and if you can see how much fuel is in the canister i know that would be a pain but if your system is draining back or sucking air it will not be full. I would run the return fuel line in a bucket and after you get a little in there stick the hose in to see if you are getting bubbles out of the line. I am not sure much about the ctis. I would adjust the air governor to proper psi and see if it stays. I have had the jam nut back off and it self adjusts.

 

[Scottro]

Thanks! Now that you mentioned the fuel sel noir I believe that I had a f-800 dump that had the same issue. We had to pull the plunger out each time to cranck. Thanks Colonel!

 

[Scottro]

Is the air governor on the firewall? Round cylinder about 3 " with a plastic adjustment cap on end?

 

[wrenchturner6238]

Is the air governor on the firewall? Round cylinder about 3 " with a plastic adjustment cap on end?

Yep take the plastic cap off and your adjuster is under the cap

 

[Scottro]

Wrench, thanks for the fuel shut off advise. That was the problem, had to turn the ignition switch to on position and manually push fuel shut off switch up and then it fires right off. I guess any diesel shop could order the switch?

 

[wrenchturner6238]

Yes they can may be different connection for electric. Or you can probably find one on ebay. Or till you find one take the solonide off and use the E kill cable. I think it returns when you push it back in.

 

[98G]

The air over pressure most likely isn't related to the CTIS or the governor.

Your PPV is stuck, so the governor is never seeing the pressure and keeps building air. You're hitting the pressure relief valve at 150psi.

Solution - replace your air dryer and PPV.

 

[Scottro]

Thanks 98G! I'll follow up on this.