She's turning over, but not nearly fast enough

[ajkaup]

Hey guys, Im new to the CUCV world. I just picked up an 85 M1009 about a couple weeks ago. she was starting, running, and driving perfectly when I picked it up and then i attempted to install a stereo without realizing it is a 24 volt system. I hooked the battery wire direct into the battery, ground to the frame and spliced the power wire into a random positive wire under the dash. As soon as i got it installed, I attempted to start the M1009 and it would turn over but not nearly fast enough and it seemed like the batteries were dead.

Both batteries are new within the last few months, so i took them out and charged them seperately which didn't take long and they were both reading 12.9v. I put them back in and tried starting it again with the same results.

I was a little confused at this point so i started testing all the volts and fusable links. I pulled off all of the stereo wiring that I had installed previously to make sure that i wasn't pulling power away from anything else, and returned it to the way it was. everything seemed to be in order so i jumped the truck with a HMMWV and she fired right up. I drove it a good 20 miles to try and get my voltometer to show a positive charge and it would barely even read on the gage. I turned it back off and again it wouldn't start. Now I'm just completely confused and need some guidance.... Can anyone help me?

 

[ajkaup]

Also, can anyone tell me why I could jump the M1009 with a HMMWV if fresh charged batteries didn't help at all?

 

[Matt65]

Welcome to Steel Soldiers!

 

[Ken_86gt]

could be a bad ground?

 

[corelokt]

I'd question your battery connections. At the batteries, at the firewall, at the starter and at any grounds. Might as well clean every connection you can find under the hood, big and small. Use star washers and di-electric grease.
If your headlight plugs are original you might want to replace them as well. Both vehicles of mine had corroded terminals at the lights. I run mine powered through separate relays for hi and low beams. Running them as is pulls a lot of juice through the fuse box circuit and the light switch. Things will last longer and your lights will be brighter powered with their own feeds and switched on and off from the original wiring. People have issues with the fuse boxes being corroded as well. I've not run into that.

My headlights are wired like such:

12V - circuit breaker (as close to the 12v source as possible) - Wire run to the relays for power - Relays - Use original wires to each headlight hi and low.

To switch the relays : Hi beam and low beam wires to each relay respectively - Other side to ground.

I moved my relays to inside the cab for reliability.

 

[hunderliggur]

" I hooked the battery wire direct into the battery"

Probably the first place to start looking for a bad connection. Jumping bypasses the batteries and sends the power to the under hood 24V bus bar on the firewall.

 

[engineman2]

Welcome to Steel Soldiers!
"can anyone tell me why I could jump the M1009 with a HMMWV if fresh charged batteries didn't help at all?"

If the charged batteries didn't help I would say a connection issue at the batteries or buss bar is a definite possibility. I think despite the squirrely wiring of a cucv, a bad alternator can drain the batteries. So check both alts as well even though this sounds less likely.

 

[Warthog]

You charged the batteries but did you load test them?

I have seen brand new batteries that had a bad cell and would show 12.7v after a charge but went to crap when under load.

Start simple and work your way up.

Which random wire did you connect it to under the dash? Some of them are very important to the happiness of the electrical system.

Have you checked out the CUCV Wiki and stickies?

Have you down loaded the FREE technical manuals that have the wiring diagrams in them