Ongoing electrical saga

[LaCroix09]

Aloha TJ geniuses,

I'll make this as succinct yet complete as possible. After rebuilding my motor and transmission, my 2000 4.0 has been driving like a dream with the exception of what I believe to be an electrical problem.

• Initially, it would occasionally fail to start but would attempt to turn over. After a few tries, it would usually start.
• This got worse and I decided to replace the starter, which solved the problem temporarily.
• After a couple months of weekly driving, it would start fine but then bottom out and die if I didn't give it gas. Sometimes it died either way.
• This also got worse but remained intermittent.
• As of the other day, it started dying randomly while driving. When I'd try to start it again, I wouldn't get the chime when I turned the key. Jeep would start after a few tries and some prolonged turnover.
• Now the chime on start up is absent even on a cold start

A few other considerations:

• Battery is new
• Fuel line is new
• Spark plugs are new
• Ignition coils are new

I have an old thread referencing a startup issue I had but seemed to be temporarily resolved by switching to my spare key. Best guess I have is alternator but assuming my Jeep's voltmeter is accurate, I'm not dropping power. No codes or CELs.

As always, thank you so much for your help!

 

[Redjeepht]

Not sure if this will help, when I was having weak, then. Eventually No starts, I changed the starter and it cranks like new

 

[Redjeepht]

Sorry I missed that you replaced the starter

 

[Feralkid]

Check all the grounds

 

[cpwolf]

I agree, I’d start making sure your grounds are solid. Also,,,,depending on where you got the starter, I wouldn’t trust some parts store to not have a wonky one out of the box

 

[macleanflood]

Should have a ground strap on the passenger side of the engine near the battery. My 97 has another cable running near the alternator to the frame. And there's a big one on the firewall.

Resource section has the factory service manuals for your Jeep. Section 8w will have a diagram showing all the grounds.

Next thing to check is if you're getting 12v on the little cable on the starter when you turn the key to crank. You can also put the key on run and jumper the big and little terminals and see if it cranks and starts.

-Mac

 

[ItchyDong]

I’d be checking fuel pressure and cleaning the IAC per instructions on this forum.

 

[hear]

The starter isn’t why he’s having trouble keeping it running. That smells like bad ground, or possibly ignition or crank sensor.

 

[g.hayduke]

If it cranks, the starter is working and can safely be ignored as a possible cause of the OP's problem.

 

[g.hayduke]

Are there any codes?

 

[LaCroix09]

Ah forgot to mention all grounds have been replaced and upgraded with beefier ones with copper fittings, EXCEPT the little braided one from the firewall to the hood. I think I may have that one laying around and should definitely replace it as well.

Ignition coil, lines, and plugs are all new so shouldn't be that.

Starter is new and seems to be functioning properly.

Fuel pump is new. Fuel rail is new.

(there isn't much that's not been replaced unfortunately)

No codes.

 

[macleanflood]

New doesn't mean it works.

-Mac

 

[CharlesHS]

Verify terminals for the Starter and ASD relays are clean and the relays are not loose in their sockets.
Measure the resistance (ohms) across the relay magnetic coil (terminals 85 & 86) for the relays...
The measured resistance should be around 70 ohms; if the resistance is or becomes too high; the relay may not energize or remain energized.
Verify supply voltage (terminals 30), trigger voltage (terminal 86) and ground (terminal 85) provided to these relays....

 

[LaCroix09]

That's a bit over my head, but I think I can figure it out.

I am guessing you would measure those resistances and the voltages with the ignition on?

 

[CharlesHS]

Resistance would be measured with relay removed and voltages would be with relay installed.

 

[hear]

Something like this can make troubleshooting the circuit a lot easier.

https://www.amazon.com/dp/B002NRBV7O?tag=wranglerorg-20