1994 M1123 won’t start. Please help!

[Mogman]

Well, not getting 24V to the IP solenoid wire 54A and or that wire not being plugged into the correct place on the IP would certainly not yield any fuel to the injectors.
It is also possible the IP is bad, there are many non running surplus trucks coming out now with bad IPs.

 

[MrLucky7137]

No you do not, that engine will fire off of ether without the glow plugs, you said you replaced the glow plugs, a simple volt meter test will tell you if you arre getting power to the glow plugs and if the PCB is cycling them correctly.

Copy that. What is an EESS?

 

[MrLucky7137]

Well, not getting 24V to the IP solenoid wire 54A and or that wire not being plugged into the correct place on the IP would certainly not yield any fuel to the injectors.
It is also possible the IP is bad, there are many non running surplus trucks coming out now with bad IPs.

i need to figure out why it’s not getting 24v to 54A

 

[Mogman]

Copy that. What is an EESS?

PCB and EESS are pretty much used interchangeably

 

[Mogman]

Are you getting a wait light at all? is it on for 6-10 seconds when first cycled (multiple cycling can cause the wait light to no act correctly)

 

[MrLucky7137]

Hello everyone thank you for adding me. My M1123 cranks just fine but won’t start. I have 2 good batteries, I’ve replaced all of the glow plugs, cleaned and replaced the fuel filter and the air filter, I did try a little bit of either just to see if it would fire and it sure wanted to. The fuel injection pump is only getting 4.9 volts to the A wire on top. I have cleaned and tightened every battery connection and ground I can find. Thank you

Is there anyone that can offer a helpful suggestion? Preferably without a bunch of useless abbreviations please. I need to figure out why my IP is not getting 24v to it. I’ve fixed every bad ground and connection I can find and I have 2 good batteries. TIA

 

[Mogman]

Have you checked wire 5A at the alternator with the switch in run position?
Do the headlights shine brightly?
Do the wipers work?
Does the heater fan run?
Do the gauges show some sign of life? volt meter in the yellow?

 

[MrLucky7137]

Have you checked wire 5A at the alternator with the switch in run position?
Do the headlights shine brightly?
Do the wipers work?
Does the heater fan run?
Do the gauges show some sign of life? volt meter in the yellow?

24v at 5A . No head lights yet someone must’ve remove them before I got it. And the gauges are shot can’t read any of them right now.

 

[Mogman]

Well then you need to download the TM and start tracing back the power, as you can see in this schematic that 54A leaves the IP and goes to a junction, (far left side) were run power is sent several directions, the wire 54B is were the power is coming from, it connects to pin A on the PCB (connector under the hood) so that would be the next logical place to look.

 

[Mogman]

If there is no power there then you can back up to the run/start switch, as you can see wire 29A goes to a junction where it becomes 29C and goes to pin B of the PCB, I am assuming you have power to the switch as you are cranking the truck, if you have power at pin B on the inside connector and no pwer to pin A on the outside connector then the PCB is defective.
Of course this is all easier to see directly from the TM.

 

[MrLucky7137]

Have you checked wire 5A at the alternator with the switch in run position?
Do the headlights shine brightly?
Do the wipers work?
Does the heater fan run?
Do the gauges show some sign of life? volt meter in the yellow?

ok I definitely have 24v going to 5A. I can now hear the solenoid clicking on and off. But I’m still not getting any fuel to the injectors.

 

[Mogman]

Well, the IP needs only three things, a fuel supply, 24V to the run solenoid and the engine to turn the input shaft, if all three of those things are there and there is no fuel out of opened (loosened) injector lines then the problem is in the IP, as I said earlier very common these days..

 

[Mogman]

I have been around diesels for many decades and have never seen these kinds of failures, it is common here on the ranch to let a tractor sit 5-10 years with none of these kinds of issues, I did read that JP has additives that give it a rather short shelf life and the military likes running JP in the HMMWV.

 

[MrLucky7137]

Well, the IP needs only three things, a fuel supply, 24V to the run solenoid and the engine to turn the input shaft, if all three of those things are there and there is no fuel out of opened (loosened) injector lines then the problem is in the IP, as I said earlier very common these days..

copy that. Do you have a good recommendation on a place that will rebuild it? Is that my best option?

 

[Mogman]

Depending on what part number you need there seem to be allot of new ones on Fleabay cheaper than you can get one rebuilt.
Just be careful what ever you decide..

 

[Mogman]

If it were me I would not give up just yet on the IP, I would pop the top off and have a looksee inside, BTW that would require a 5 point "torx" security bit.
But you need to be mechanically inclined and very clean and meticulous, of course you will need those skills to R and R the IP.

 

[aghumvee]

Usually the fuel valve under the injector pump top cover gets stuck/rusty from sitting. The solenoid will move like normal but the valve will stay in the closed position. Put some transmission fluid in there and work the lever back and forth until the spring moves it on its own again. Let it sit overnight or put back together and see if it starts.

 

[Mogman]

One thing if you go that route is watch a couple youtube vids on that cover, you want to make SURE you get the linkage right when you put the cover back on or you could have a runaway engine, it is best to leave the injector lines loose so if you get fuel flow to them you can pull the solenoid wire and crank it to make sure you have stopped the flow,
As aghumvee said sometimes the linkage is stuck in the off position, sometimes the pump pistons are stuck in their bores and working with it for a while will get them going again, then some times it is just a exercise in futility..

 

[MrLucky7137]

No you do not, that engine will fire off of ether without the glow plugs, you said you replaced the glow plugs, a simple volt meter test will tell you if you arre getting power to the glow plugs and if the PCB is cycling them correctly.

Ok so I got it running after having the IP rebuilt. I replaced the fuel pump on the block as well, started right up and ran great. This morning it started right up and idled for 20 minutes No problem. Now it starts after cranking for about 20 seconds runs for about 20 seconds and dies every time. Please help

 

[Mogman]

Ok so I got it running after having the IP rebuilt. I replaced the fuel pump on the block as well, started right up and ran great. This morning it started right up and idled for 20 minutes No problem. Now it starts after cranking for about 20 seconds runs for about 20 seconds and dies every time. Please help

Just the basics, replaced the filter? cleaned the fuel tank/pickup screen? removed the check valves?
Cranking for 20 sec is too long as you will fry the starter.
If you open the filter drain valve and crank the engine does fuel come out?