M813 Leaving me stranded

[Evansville Collector]

Guys, I need help with this! I have broken down twice because of this now and can’t be stranded anymore. This is an M813 with the 250. When driving the engine suddenly dies with no warning. I pull over, move the run switch to “start” and absolutely nothing no click from the starter or anything. I do have full gauges and lights. I can typically get going again by pulling and tugging on the wires leaving the control box but then the first bump after it typically quits again with no warning. I changed the PCB to a spare on the side of the road and with several wiggles afterword’s and using my loader tractor to move the last half mile made it home.
With the help of my brother we took apart the connector that goes into the PCB. We found the female end on the connector seemed to be stretched out. We cleaned, and bent in a touch and reassembled. Now it is much harder to slide on and off the box and seems to fit tight.
It was fine that day. Then the next morning I went to start, battery on had all gauges, flicked switch to start nothing. If I continue to hold the switch to start and wiggle around on the transfer case lever moving it from neutral to high range it started and ran fine. When I left, the first bump and she died immediately. Only thing that was different this time is I could start again by engaging the starter and did not have to wiggle on those wires.
Question 1: is there a safety switch on the transfer case to keep it from starting?
Question 2: Do you think I still have a problem with that connector?
Question 3: Since I changed the PCB to a spare is it possible it has a fault in it and that is why it seems to have fixed one problem and created another?
At a loss here.

 

[acme66]

Start by taking any ground staple loose you can find between motor and frame, body and frame and clean them. I had a phantom starting issue that only resolved itself when I put a larger ground between starter-motor-frame.

Ken

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[Evansville Collector]

Start by taking any ground staple loose you can find between motor and frame, body and frame and clean them. I had a phantom starting issue that only resolved itself when I put a larger ground between starter-motor-frame.

Ken

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The grounds were all cleaned about a year ago when the truck was painted. I did check the ground by the box and it was clean. However, I cleaned again and bolted back down.

 

[acme66]

Do the same for the starter motor and block. I literally had to add new lines to fix mine despite there being nothing obviously wrong with mine. Might be the motor is grounding through the starter and if that had a sketchy ground the fuel solinoid is snapping shut as a result. It is a serious contender given what you describe of random issues possibly related to bumps and then coming back after wire yanking. Still might be something else but given that it happened with a spare module you should definitely rule it out. Grab a 9/16 and crack, wiggle, snug each ground before going forward.

Ken

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[acme66]

Is there a clutch depressed lockout on the 813? If not and it could be started in gear then I can't see anything in the high/low having a lockout. Wires rubbed through on linkage or body? When you follow the wire loom see any signs of crushing, rubbing or impact?

Ken

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[acme66]

To fix mine I had to replace the ground from the starter solinoid with a larger wire and replace the starter to frame ground. The issue didn't come up again after that. Never could see or feel anything wrong with the wires I changed but the issue resolved after.

Ken

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[Evansville Collector]

If there is it is not hooked up on this truck. It will start with the clutch in or out. I have started the truck since I got it in everything from low to high and neutral. As I was holding start and pulling up on the transfer lever you could hear the starter kick in rapid succession like it was being told to go/stop go/stop. But then when I pulled the transfer lever all the way up to high it started no problem. An idea I have is the fuel shutoff solenoid. I am not with the truck now to look but what if it is telling the PCB that the engine is running and thus not letting the starter kick in. That would explain that when a bump is hit the solenoid is shaken causing it to cut fuel just enough to stall the engine and when I turn the start switch again the PCB thinks it is still on. Since the symptom changed and allowed me to easily restart once it died over the train tracks that tells me I may have had a spotty wiring issue that is fixed, and now its down to the root cause of the solenoid.

 

[acme66]

Could be, can you bump the starter on an 813 while it is running? I wouldn't have thought they had the ability to sense when running. Just trust me, step on on strange electronic stuff is adjust all grounds from the battery box out. If it wasn't for the shutdown and the no start then I would tell you to crank in the override fuel screw or a few things on the starter but the two share only two systems, power from the main switch and ground. Measure for 24v at the solinoid if you see it then ground. You already know the switch works because of other power in dash.

Ken

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[Evansville Collector]

I will clean every ground at the next opportunity!

 

[red]

The fuel shutoff solenoid on these are simple, doesn't send any info back to the PCB. No clutch safety switch or any tcase safety switch. Sounds like either a loose wire or a bad ground.

 

[Floridianson]

The only thing I can add on this is carry a remote starter switch in the truck. If the PCB box or anything other than the starter fails screw in the finger set screw by the electric solenoid and hook up your remote starter switch to get her home. Most mechanical injection deisels if you can bypass the electric shut downs but get the starter to crank they should run.

 

[Evansville Collector]

I am going to work on this tonight and report back, thanks for all of the input!

 

[Evansville Collector]

One more thing after I do the grounds, what tells the PCB that the engine is on or off?

 

[73m819]

One more thing after I do the grounds, what tells the PCB that the engine is on or off?

Oil pressure

 

[snowtrac nome]

I would be suspect of your ignition master switch may have some burned contacts you can check it with a simple test light or volt meter.

 

[Shirehorse]

Oil pressure

Is this the same on trucks with mechanical oil pressure gauges? Or is there a seperate sender for the PCB?

 

[acme66]

Boy I could be wrong but I am quite sure it is a one wire sender going only to the gauge varying just with voltage in relation to temperature. That motor is the latest in 1950's tec. An NHC 250 would run with fuel and a bumpstart, to my knowledge there are no controls you speak of on the motor. It just isn't that complicated. I could disconnect every wire, connect it to a jug of fuel and short the starter with a wrench and it would run just fine. The upper switch controls main power, the key energizes the fuel switch and starter.

Ken

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[Shirehorse]

The gauge is one of those that has an oil line directly from the block to the gauge, sans sending unit. You're right, you can run them with no electronic controls, I have seen it done several times myself, just never had to do it.

The functionality that I'm speaking of is the PCB preventing starter engagement while the engine is running. I was thinking signal from generator, but I'm not sure.

We actually found the problem on this truck tonight, but I'll let EC explain it, because I wasn't there for the whole thing.

~Brian

 

[73m819]

The oil pressure gauge is NOT a mechanical but a electric one with a sender, this sender also sends a circuit to the pcb start relay which it opens, preventing starting when the engine is running.

 

[Evansville Collector]

Hello! My brother actually found the issue last night and snowtrac nome was the closest now that I see the comment. On the back of the run/stop/start switch one of the connections had frayed almost completely through the wire at the connector where it plugs to the back of the switch. So it was literally attached by a thread or two. We could duplicate the issue by starting the truck, and wiggling that wire and the truck would die. We could then disconnect that wire and the truck would not start. So we installed a new connector and it worked like a champ. After that we wanted to be thorough and messed with the other wires on that switch and another one caused the truck to die. Another new connector and no problems. Successfully handled rough sections of road and the train tracks with no issues. Fingers crossed we have it figured out! Thanks for all of the help!