CUCV - Slow cranking when cold

[wbdodgeiv]

I have a M1009 that has developed a problem starting when the engine is cold. When I first get in and try to crank it, it starts off at normal speed and within a few revolutions slows until its nearly stopped. I typically let it starter cool at this point. If I hold the key it will barely roll the engine over but if I continue to hold for 5 sec more or it will begin to crank faster and then it starts. If I try to restart at that point it starts very easily. It's only after sitting, generally overnight, that it does the slow to crank thing.

The batteries are less than 2yrs old and the cables seem fine. The cables are warm to the touch after the starter has strained which leads me to believe that the current is going down to the starter and not being wasted as heat at a bad crimp or loose terminal.

I'm down to something being wrong with the starter or an injector is leaking and it's hydrolocked. It isn't making oil so probably the starter? I've found lots of threads on no or slow starting and it is usually batteries or a starter, I haven't found another thread where the starter slows down then speeds back up before starting the engine.

 

[Barrman]

Get your batteries load tested. They should be 800 Cold Cranking Amps each. If below that. Replace.

Next is all the connections of the 24 volt path from the batteries to the starter motor. Undo, clean, sand, tighten after inspection.

Then you have your starter motor itself. If everything else was good to this point. 99% starter issue caused by under voltage/Amp starting attempts.

The trouble shooting section of the -20 manual walks you through the exact same steps.

 

[wbdodgeiv]

Get your batteries load tested. They should be 800 Cold Cranking Amps each. If below that. Replace.

Next is all the connections of the 24 volt path from the batteries to the starter motor. Undo, clean, sand, tighten after inspection.

Then you have your starter motor itself. If everything else was good to this point. 99% starter issue caused by under voltage/Amp starting attempts.

The trouble shooting section of the -20 manual walks you through the exact same steps.

Wouldn’t both of those involve cranking slowing and then stopping, it’s the speeding back up that puzzles me.

 

[MarcusOReallyus]

I'm down to something being wrong with the starter or an injector is leaking and it's hydrolocked. I

Bad injectors don't cause slow cranking. If it were hydrolocked it wouldn't be turning over at all. Your problem is in your batteries, cables, connectors, or starter.

Looking at cables and connectors is not enough.

 

[Barrman]

Think of it this way. The first owner had a budget in the trillions. They threw lots of money at hundreds if not thousands of people to figure out a way to diagnose, test and repair anything that could go wrong on your truck. Then they threw more money at people to make several thousands of pages describing that process to people with no higher than an 8th grade education. Amazingly enough. The product they came up with. The CUCV technical manuals do exactly that.

The TM which can be downloaded or viewed from this website and others for free has a 70 plus page electrical trouble shooting section in the manual ending in -20. The very first thing in that section is about making sure you have fully charged and load tested batteries. Everything after that is based upon fully charged and load tested batteries as a given.

So, yes it reads as if you have an internal start motor issue or maybe a Bendix engagement clearance problem. Maybe even an oil supply/main bearing dragging nightmare. But, to eliminate all the cheap and easy possibilities first. Load test your batteries, check all the wiring connections and the wiring itself first. Following the steps in the TM works very well.

 

[cucvmule]

Check the pos cable to the starter solenoid. Check the purple wire going to the solenoid. Are they tight?

How long has it been since the starter has been serviced? Brushes and bushings do not last forever and the symptoms you list would cause some of the same problems.

 

[wbdodgeiv]

Update: I got this fixed a while ago and forgot to post about it. I tested the batteries and the back battery was noticeably weaker than the front, it dropped to 10.5v where the front dropped to 11.5v when I activated the 100amp battery tester. I replaced it and it cranked better but still had issues. I pulled the starter and found that the gear was loose and wobbled around. Rather than fix it I replaced it with one of the gear reduction starters from DB Electrical. Starts great now.

Still seems to loose a bit of prime. I have a check before my spin on fuel filter but it still doesn't seem to keep the injectors pressurized after it sits. I need to add a fuel pressure gauge at some point.