No start issue on my XJ

[Cottontail]

Went to start my XJ the other day and it wouldn't start. Not surprising, as I haven't driven in a couple months. Jumped it off and let it run about 30 minutes with a couple runs around the neighborhood. Shut it off and when I went to start it again it wouldn't do anything - like there wasn't even a battery in it. Jumped it off again and it started, but died when I took the cables off twice, then ran the third time I tried it.

Today did a little test.

Jeep A with Battery A - 1998 ZJ daily driver. Battery is known good.
Jeep B with Battery B - 2001 XJ trail rig. Battery unknown.

Put battery B in Jeep A - Fired right up. Let it idle about 20 minutes
Put battery A in Jeep B - Fired right up. Tried it 10 times, no issues.
Put battery A in Jeep A - Fired right up
Put battery B in Jeep B - no response, like there wasn't a battery in it (even after Jeep A charged it for about 20 minutes)

So - does that suggest in the XJ trail rig that the battery is bad, that the starter is bad, or that the combination of a weak starter and a weak battery is the issue.

 

[RCP Phx]

A voltmeter would have been a lot less work!

 

[bruceb]

could be corroded battery cables underneath the insulation.
could be your grounds need to be refreshed.

 

[lawsoncl]

A voltmeter would have been a lot less work!

Yup, far less work than lugging batteries around.

DO NOT UNHOOK THE BATTERY WHILE THE ENGINE IS RUNNING! That's an old school, redneck, pre-computer trick that risks frying the electronics. Without a battery connected to smooth out the voltage from the alternator, the voltage spikes from the alternator can damage the computers. For those who claim it can't, I've seen it happen multiple times. The older Ford engine computers will literally start smoking if you do this.


(Sorry if this sounded harsh, but I'd rather your next post not be titled "Got new battery, now it cranks but won't start".)

Personally, I'd start by looking real hard at the battery terminals and cables. Poor connections will cause problems starting and charging. Go get a cheap voltmeter to figure out if you're charging, or dropping voltage across the cables when you try cranking. Even the el cheapo Harbor Freight special works fine for this.

 

[maxbraketorque]

I suggest checking cable attachments and the starter. The starter that came with my XJ was oil drenched due to a leaky remain seal, and it would intermittently work. But if the connections on the battery and charging cables are obviously corroded, that's a better bet as a starting point.

 

[Cottontail]

Didn't mention - the cables attached to the battery are all new.

And it would have taken more time to drive to the store to get a voltage meter than to swap out two batteries 5 feet apart in the garage.

Still not sure why the XJ starter will start with one battery and not the other, and the ZJ starter will start on both of the batteries without any issue.

 

[lawsoncl]

The starter that came with my XJ was oil drenched due to a leaky remain seal

An oil soaked starter is usually caused by the o-rings in the oil filter adapter.

And it would have taken more time to drive to the store to get a voltage meter than to swap out two batteries 5 feet apart in the garage.

I'd get one for the future. If you do any automotive work, a little knowledge and a meter will save you money in the long run, by letting you test things instead of replacing expensive sensors (with poor quality after market parts).

 

[techno1154]

Did you get any sound from the starter?

If no, being by checking the starter relay in the PDM. This is easily verified by replacing with a known good relay, or you could remove the relay and use a jumper wire between the two large terminals only in the PDM.

The other test will be to temporarily connect a positive voltage to the small starter wire. It is usually wrapped in a harness with the starter main wire that is attached to the battery positive to the starter.

You could also crawl under the XJ and cross with a piece of wire (or screw drive) the battery main wire at the starter and the small wire which activate to the starter solenoid. Either one of these tests should get you some results and point you to your questionable equipment. A short 10 or 12 AWg wire is good enough because the AMP draw will be very little.

 

[Lost_Wrench]

So when you put battery A into Jeep B it has no issues starting?

I would get battery B load tested. I recently had a one year old interstate battery that decided it didn't like my XJ and wouldn't start it anymore. I could jump it and charge it, but it would still die and eventually cause a no start. I tested with multi-meter and the battery was good and I had no parasitic draws either. Then I took the battery in and it tested fine at the auto shop I bought it from. So I just replaced it and haven't had any more issues with the new battery.