M1009 Battery Problem

[LibertyDeuce]

Yes I know, try the search function first, which I've already done. Put new batteries in today. Tried to start the vehicle and it would only crank. The voltmeter is in the yellow zone. The wipers, horn, etc are weak. Checked the battery connections and they are tight. Although on one post, the clamp does not seem to make a tight contact. I'm hoping that this is the problem. Any comments on other possible causes I should look for.
Thanks

 

[pc3nmcb]

I know you said the batteries are new but did you check them. I have got them before that were weak.

 

[LibertyDeuce]

PC
That's one of my reactions to this mess. Thanks for the second opinion

 

[thedeliverator]

I had problems starting in cold weather until I finally pulled the batteries, had both of them load tested (front wasn't holding a charge, replaced both), and sprung for a new set of cables and clamps (were starting to show corrosion). Since there was nothing on the shelf that was an exact fit, I got some help re-creating the wiring from scratch.

Since the gauge is showing yellow, you've got the voltage available, but I suspect the starter isn't getting enough current, due to either a bad connection at the battery, starter or ground, or weak batteries.

If the batteries and cables check out, I'd check the starter bolts to see if it's loose. Install the bracket that is supposed to be there if it isn't; it helps keep the starter in place so it will make proper contact. Without it you run the risk of snapping off the bolts and possibly the corner of the engine block.

Edit: Also if you have a voltmeter available, hook that up and see what numbers you have before you start cranking and during.

 

[pc3nmcb]

I was wondering if you got a chance to check batteries, or what you found.

 

[Wolf.Dose]

I do not want to be like a teacher. However, did you measure the batteries with a voltmeter. If they read 12.8 V at last the voltmeter in the truck should be in the green. Yellow means weak batteries or bad contact.
Are all connections clean and propperly tied? Are the clamps clean inside and proberly contacting the batterie pols all round?
The harness to the batteries usually does not fail. This is from 16 year of driving a M1009. And I use used batterie harness in my M715, which is converted to a 6.2 l Diesel, without problems.
Next: Does the engine crank at at least 200 rpm while starting trials? Does the selenoid in the injection pump get a proper contact and work? I once had the problem that the shoe on the contact had a bad contact and the engine on the highway stalled. Not very funny in Germany highway traffic on a business trip.
Do your glow plugs work propperly? Most of the engines do not start without preglowing. If one or two do not work, you will not notice that. The engine starts anyway due to the other six working.
Wolf