Timothy B Demarco

On my 1995 CH 613 with a 300 Mack motor in has hard time firing. I put on all new filters and was wondering if a drain back valve could be bad. The motor has a Primary and a Secondary fuel filter the Primary fuel filter sounds empty and the Secondary sounds full. The pump actuator solenoid is working. Need a little help here.

On my 1995 CH 613 with a 300 Mack motor in has hard time firing. I put on all new filters and was wondering if a drain back valve could be bad. The motor has a Primary and a Secondary fuel filter the Primary fuel filter sounds empty and the Secondary sounds full. The pump actuator solenoid is working. Need a little help here.

Oh sure center me out! LOL I agree what motor is it?

I found the problem. Up on the firewall you have your starter relay and beside that is square box that has two prongs and that is a ignition ground relay and that burned up.

Hi, well i have a 78' R686st mechanic's special truck that i bought and put a 14' dump bed on and done alot of fixin up. anyway it makes this banging noise and jerks. it don't do it all the time, i can make it start doing it with heavy acceleration, etc. it has tandem 38k axles wit 4.50 gears it says. i have put all new caps on trk. I have replaced and checked almost everything i can think of, have changed trans, replaced wedges and cams, spider gears,axle gears, bull gears,axles,etc I have counted all teeth on one gear carrier, but forgot to count on frnt carrier before i stuck in back down in housing. What are the odds of having different ratio's? What is acceptable size/wear difference between rear tires?

Well if you ask me it sounds like a power divider. I just had a truck that did the exact same thing as yours and the cam inside was bad. It only popped every now and then.

I'm assuming you have an electric solenoid mounted to the injection pump governor: This solenoid would pull the fuel rack that is internal to the pump to the no fuel position to shut down the engine by starving it for fuel. Usually when these work correctly power supplied by the ignition switch releases this hold on the fuel rack allowing the governor to control curb idle. If this solenoid is sticking in the off position you can have the problems you experience. When you hit the engine with a shot of ether you have supplied fuel to it and the engine vibration probably causes the solenoid plunger to release. This is just a guess and again an assumption. In this case you would be best replacing the shutdown solenoid and not screwing around. Citing the engine does start and not shut back down until you want it to lends creedance to the ignition switch is supplying power to this solenoid. The same scenario could play out with a manual cable shutdown also if it is out of adjustment.

Rob

What about a ground relay on the firewall next to the starter soleniod, could that be a problem to, because it smokes sometimes and I'm replacing that.

I have Mack CH-600 with a mack 300 motor. We have difficulty starting it when it is warm and cold. It's wierd you spray either to it and it fires right up. Fuel filters are tight, no leaks on any fuel lines, it has a new drainback valve. So I got curious and tap on the actuator on the fuel pump and it started. Now was that just luck or could that actuator be bad. If it is bad how do you test it.