Another No-Start thread

Hey all,
'90 XJ 4.0 with starting issues, in that it won't.

The truck was sitting for a couple of years and was put back in service 4 months ago. I had a similar no-start issue back then, but cleaned up the cables and the ground and all was well - until last week. Out of the blue it won't start. Starter engaged (I can hear the gear click out) fuel pump starts, but the engine doesn't crank. I thought it might have been the battery (4 month old, but it was cheapo Autozone, so I figured it just didn't have enough ooomph anymore). Replaced the battery with Napa's best, still no crank.

It will start if I jump it from another car or from an emergency battery jumper I keep in the back.

Here's what I've done:
- Battery to starter, starter relay and block cables replaced with jeepers and creepers cables 4+ years ago. The pos end on the battery was a little gunky after the 2 year sit, but looks fine after cleanup.
- Added a 4ga cable from the firewall to the rear-most bolt on the fuel rail to enhance the braided strap ground.
- Replaced the starter 3 months ago. I thought it might be that, so I swaped in the orginal starter yesterday, no difference.
- After the engine was started, removed the pos cable from the battery, ran fine.
- Starter relay was replaced probably 4 years ago

I have another cable on the way to add an additional battery B- to fenderwell ground. I'll also replace the terminal ends with ends from 5-90.

I plan on doing some resistance and load testing on the cables today if I can, but wanted to get opinions here on what else I should be looking at. It's driving me a little nuts to say the least ...

thanks in advance -
AJ

FIRST--never, ever, EVER disconnect a battery cable while the engine is running on a alternator equipped vehicle. That old trick DIED with generators. You run a very HIGH risk of damaging major (read that as EXPENSIVE) components.

Now, you have a battery that is good, fully charged, and passes (a**uming) a load test. And yet, it won't crank the engine over on its own. It will, however, crank the engine over when you goose the available amperage.

I would suspect that your main cables won't carry the load.

Do a voltage drop test and post up your results.

EDIT: voltage drop testing: http://www.aa1car.com/library/voltage_drop_testing.htm

I agree that disconnecting a battery cable on an alternator engine while engine is running is a very bad idea. Some get away with it but why take the chance??

It is likely that your cables are faulty. As Joe said, get voltage at the battery, then at the starter itself with the key on. You probably have voltage drop.

Will do more testing tonight, but had a quick read this morning:

No-load readings -
Battery post to post - 12.3v
Battery post to clamp, both sides - 12.3v
Battery post/clamp to starter relay - 12.3v

Will load test tonight. What gets me is that these cables are heavy duty cables and not that old. Ahh well, nothing lasts forever, and they are certainly the most obvious point of failure.

Will let you know -

Sounds like more ign. switch than anything else.

Attacked the wires yesterday with a wire brush and took the connections down to bare wire at the battery and at the block and all is well.

whew.

thanks guys

Glad you got done, now go wheeling for the weekend!