Bj Hinson

On the 94 it is the primer pump. I pumped the shit out off it and it started better. I haven't tried it on the 95 yet but both had new primer pumps last year. Seems weird that it would break that fast

The manual says it should have a electronic actuator on the back of the pump but there's no wires on the back just a fuel shut off on the side. I'm sure it's mechanical

It does it even when they are in the shop with heat on

It is an electronically controlled motor. Electronic foot feed and the cruise and high idle are both electronic.

I have a 1993 R model with a 400 Mack. It will rev wide open then shut itself down. I checked the turbos for oil and they are clean. I thought it could be getting to much air so I replaced all of the fuel lines from the tank to the fuel pump and it is still happening. Other than the pins on the plug in to the fuel selenoid on the fuel pump being worn or having a bad connection I am at a loss for what to try next. Any Ideas.

I have 2 identical ch 600 Mack trucks. Unit 110 is a 1994 and unit 111 is a 1995. Both have 400 Mack engines. They will both crank over until the batteries are almost dead before they start. I added check valves behind the fuel filter housing,replacing the main fuel line from the tank to the filter housing and also the three lines from the filter housing to the fuel pump. There isn't any fuel leaking around the transfer pump or dust accumulation to indicate a fuel leak. I think it could be the selenoid on the fuel pump as I have already replaced the selenoid in the dash by the fuse box. Any help would be appreciated as I have had these units out to the mechanics shop numberous times and am getting tired of paying time and time again for zero results.