New Memeber and Engine Problem - NHC-250 Cummins

[Evansville Collector]

Hello!

I am new to the group and in Evansville Indiana. My truck is a 1970 XM813 which is a 5 ton 6x6 with the NHC-250 Cummins. I have had it for about a month and so far I like the hobby.

The truck generally runs like a top and has very minor or few leaks. I was driving down a state highway and noticed speed decreasing, upon adding throttle that did not help, and I realized as I pushed the clutch in engine had died and was just being turned by the still rolling tires. I pulled over into the break down lane. Turned everything off. Did the normal start procedure, battery, lights on, press the start button. Engine starts instantly as usual and idles fine. Push the throttle a few times ok. Press it again it straight dies. At this point I am thinking I am out of diesel or have a fuel issue.

I hit the starter again and nothing, the starter does not engage. With the road noise it is hard to hear for sure, but I dont believe there was any clicks, etc. But for sure the starter was not turning. It has never done that before. I climb under the hood and start banging on the control box with a wrench. No help. I tug around and wiggle the wires in control box area, climb down, almost get hit by a motorist who was a foot off my door, got in the truck, hit the starter and it started perfectly. Idle good, revs good. Close up hood, etc, get about a quarter of a mile up the road and total engine loss again and the starter would not engage again.

I had a wrecker tow me to a nearby hotel truck area as it would have been crazy expensive to tow it home. I was also unsure if having the front wheels off the ground and being pulled very fast would damage anything in the transmission.

Let it sit overnight, and still in the morning, the starter will not rotate. I replaced the control box with a spare I had same problem. I do know I might have damaged wires connection in the round connector as I did not realize there is a second nut and thought it was just stuck. So my friend messes with the wires pushing and pulling on the harness that goes into the control box. I tried to start it and starts and runs no problem. I drove it home and have moved around the yard several times with no problems. However, I am worried to take it back on the road until I am 100% this is resolved and wont come back and leave me stranded or in another dangerous situation.

I have attached some pictures showing some corrosion in that plug.

1. Do you guys think a bad connection in that plug could cause the truck to randomly die and for the starter to not go?
2. Do you think I can fix by hitting with contact cleaner and adding some more solder to the connector?

 

[USAFSS-ColdWarrior]

Welcome aboard Find a bunk, stow your gear, and prepare to get underway

I cannot add anything constructive concerning your engine problem.
We are relatively new owners of a 1969 vintage XM818 Semi-Tractor with the same engine as yours. Hence, I'm subscribed to this thread for "educational purposes".

Again, welcome aboard !

 

[porkysplace]

I think you have 2 separate problems . The truck loosing power and dying sounds like a fuel problem , I would start with new filters. There is also a electric fuel solenoid by the IP there is a screw on it to open it with out power. The starting problem could be those cruddy connections . I would clean them up before you grease them . I would also start at the batteries and clean all the connections to the starter and grounds . Pretty much go through all the electrical plugs and clean them . I would also charge and load test the batteries just so you what you have.

[h=1]cummins 250 fuel system troubleshooting[/h]
[h=1]full shut off solenoid on NHC250?[/h]

 

[simp5782]

Connecting issues start my cleaning all connectors with vinegar and a spray bottle. Then add stabilent 22. Napa number is CE1. Its pricey but well worth it.

Dirt and old crud along with moisture and vibration play heck on our systems.
https://youtu.be/ym_c5Rpz7Uo


Sent from my SM-G860P using Tapatalk

 

[Scar59]

I think you have 2 separate problems . The truck loosing power and dying sounds like a fuel problem , I would start with new filters. There is also a electric fuel solenoid by the IP there is a screw on it to open it with out power. The starting problem could be those cruddy connections . I would clean them up before you grease them . I would also start at the batteries and clean all the connections to the starter and grounds . Pretty much go through all the electrical plugs and clean them . I would also charge and load test the batteries just so you what you have.

Porky has you headed in the right direction. You have an electrical connection/ground issue (several?). Take the batteries out of the truck and charge them independently. Then load test them. Check and clean all connections to the starter, including the starter solenoid terminals. A little dielectric grease goes a long way. Change the fuel filter (located in left front wheel well). Don't gorilla the center bolt/square washer/
O ring. ( It takes a lot to clog that filter). Speaking of filters, you need to modify the oil filter from the existing cartage type to spin on type. I have the adapter kits listed in the classified. It won't fix your electrical woes, but it will make your first filter change a breeze.

 

[Evansville Collector]

I think you have 2 separate problems . The truck loosing power and dying sounds like a fuel problem , I would start with new filters. There is also a electric fuel solenoid by the IP there is a screw on it to open it with out power. The starting problem could be those cruddy connections . I would clean them up before you grease them . I would also start at the batteries and clean all the connections to the starter and grounds . Pretty much go through all the electrical plugs and clean them . I would also charge and load test the batteries just so you what you have.

cummins 250 fuel system troubleshooting


full shut off solenoid on NHC250?

Thanks for the help guys. I will review all of this and for sure treat it as two separate issues. It does have a shaky idle sometimes when the engine is cold started. Will inspect fuel system and change filter.

 

[Evansville Collector]

Thanks everyone for the advice! I tried replying from work today but the site was so slow I could not get it to post. Now it seems to fast though. Tonight I changed the fuel filter and put in new o rings. The old filter was very dirty and some had some large sediment in the can. I am certain it was restricting fuel to the engine and that might be what killed it off. Seems to run and idle perfectly now. On an unrelated note I removed all coolant lines and flushed the system. I have all new hoses on the way and am going to refill with antifreeze from cummins that has the correct additives. I expect to tackle the grounds and cleaning the connector this weekend. On a side note the temp gauge smoothly goes from cold to maxed out when the engine is at temp a laser reader shows it well under 200. So I think ive got a bad ground somewhere in the dash and plan on grounding out that gauge if cleaning the other grounds does not help. The old owner cleaned most grounds except for the one behind the battery box which might be the most important. Well see.