M923A1 no start.

[Hooper]

Ever since I have had this truck it has had a bit of an erratic idle. It got better after a long trip so I figured it was just dirty injectors.Unlike the other 5 tons upon start up, the idle would always go up by its selffor a couple of seconds and then come back down. The other odd thing. When Iwould step on the accelerator it would not snap back to rest like a normal NHC250 does. It will start on starting fluid now but will not stay running. Thetruck is not in a great location to work on it so I thought I would try theexperts here for some advice. Any help is much appreciated.

 

[wreckerman893]

You need to make sure you have fuel to the Injector Pump first. Check the big filter under the drivers side firewall (outside). That filter is a PITA to service but I'd start there. If memory serves me right that is the only fuel filter on the truck unless they added an inline or screw on somewhere else.
If there is no restriction on the filter you may have a small leak in the line that is allowing air to be sucked in. This kind of leak is a PITA to find. You may have to pressurize the tank (do not put more than a few PSI on it) to find it. You can do that by wrapping a rag around an air nozzle and putting it in the fuel tank filler neck.

 

[Hooper]

You need to make sure you have fuel to the Injector Pump first. Check the big filter under the drivers side firewall (outside). That filter is a PITA to service but I'd start there. If memory serves me right that is the only fuel filter on the truck unless they added an inline or screw on somewhere else.
If there is no restriction on the filter you may have a small leak in the line that is allowing air to be sucked in. This kind of leak is a PITA to find. You may have to pressurize the tank (do not put more than a few PSI on it) to find it. You can do that by wrapping a rag around an air nozzle and putting it in the fuel tank filler neck.

Okay, first off thank you for the answer. I must add something to the story. The truck was parked by a busy street for a few nights. When I got in the truck I noticed that the fan switch was turn on....Whatever someone got in the truck but it was locked. Then as I starring at the injector pump I kept thinking it must be simple. It ran good a week ago and now nothing. Then....there it was....light from heaven struck my brain. The fuel shut off lever was pointing backwards. Some knob job pulled the emergency shut off cable out and then pushed it back in. I did not know it did not go back on its own. I excitedly pushed it back and the truck fired right up. The idle will still periodically drop but she lives!!!!!!!

 

[Brad Nitzke]

Okay, first off thank you for the answer. I must add something to the story. The truck was parked by a busy street for a few nights. When I got in the truck I noticed that the fan switch was turn on....Whatever someone got in the truck but it was locked. Then as I starring at the injector pump I kept thinking it must be simple. It ran good a week ago and now nothing. Then....there it was....light from heaven struck my brain. The fuel shut off lever was pointing backwards. Some knob job pulled the emergency shut off cable out and then pushed it back in. I did not know it did not go back on its own. I excitedly pushed it back and the truck fired right up. The idle will still periodically drop but she lives!!!!!!!

I was going to say that. It happened to one of the dump trucks i was using. its a pain to find and when you do its like DUH. haha. happy trails.