Engine won't turn over with daytime heat - JeepForum.com
 
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post #1 of 5 Old 05-28-2020, 03:06 PM Thread Starter
outside89
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Location: Portland
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Engine won't turn over with daytime heat

Hi Jeep people.

I have an 02 TJ, it has had some electrical problems in the past but has been working fine until recently.

2 weeks ago it wouldn't start after I drove it to the river. After taking apart the starter and trying to clean it on location, I had to push start it eventually to get it home. I ordered a new starter and when I installed it, nothing. It still wouldn't start. I tried again that night and it started right up! It started again early the next morning. When I tried to start it mid-day after the sun had a chance to heat up the hood, it wouldn't start again.

This sequence of events happened 2 days in a row.

I'm convinced it is a heat issue. I've read up on "heat soak" and I'm not sure if that exactly fits these symptoms. I also read that heat increases electrical resistance so maybe this is a wiring overload??

Does anyone have an idea of how to approach this and diagnose what needs to be fixed? This is my daily driver so I am trying to get it running as soon as I can.

Thank You!

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post #2 of 5 Old 05-28-2020, 03:52 PM
CJ7-Tim
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When it does not start, is the starting doing nothing at all, or does the starter make the usual noises, but the engine does not run ?




Heat soak is a fuel delivery issue, excessive resistance is a wiring issue. Eliminate one or the other.

Have the starter tested, new does not means it is working right. Have the battery Load Tested inside a test machine.

Test the fuel pressure: after not running for 8 hours, while attempting to start, and while running.

Perform basic trouble shooting of the start and charge systems. Remove, clean, and firmly reconnect all the wires and cables to the battery, starter, and alternator. Look for corroded or damaged cables or connectors and replace as needed. Copper wires should be copper color, not black or green. Do the same for the grounding wires from the starter to engine block, the ground wires at the coil, and the ground wires from the battery and engine to the Jeep's frame/body. You must remove, scrape, and clean until shiny, the cable/wire ends, and whatever they bolt to. Jeeps do not tolerate low voltage, bad connections, or poor grounds.

Place your DVOM (Digital Volt Ohm Multi-Meter) on the 20 volt scale. First check battery voltage by placing your multi-meter's positive lead on the battery's positive post ( the actual post, not the clamp ) and the negative lead on the negative post. You need a minimum of 12 volts to continue testing. Next, leave your meter connected and take a reading while the engine is cranking. Record this voltage reading. Now connect your positive lead to the battery terminal stud on the starter and the negative lead to the starter housing. Again, crank the engine and record the voltage reading. If the voltage reading at the starter is not within 1 volt of battery voltage then you have excessive voltage drop in the starter circuit.

Typical voltage drop maximums:
• starter circuit (including starter solenoid) = 0.60 volt
• battery post to battery terminal end = zero volts
• battery main cable (measured end to end) 0.20 volt
• starter solenoid = 0.20 volt
• battery negative post to alternator metal frame = 0.20 volt
• negative main cable to engine block = 0.20 volt
• negative battery post to starter metal frame = 0.30
• battery positive post to alternator b+stud = 0.5 volt with maximum charging load applied (all accessories turned on)

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post #3 of 5 Old 06-02-2020, 07:38 PM Thread Starter
outside89
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Thank you for the response.

To answer the question - when it does not start, it does not even seem to try. The battery and radio kick on but no sounds of trying to start. When it does start (at night or early morning), it doesn't sound too bad but it seems to make an extra effort before starting.

I have a DVOM and just confirmed the voltage on the battery is 12.66, I'll have to wait until someone else is around to record it while I crank the engine. The cable ends aren't very clean so I'm taking them off and possibly replacing them and then working on the rest of the wiring.
Is it sufficient to test the starter with a multimeter or is it better to bring it into an auto parts store for them to test it?

I appreciate the advice on eliminating possible causes for this.
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post #4 of 5 Old 06-03-2020, 04:42 AM
CJ7-Tim
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Quote:
Originally Posted by outside89 View Post
- The battery and radio kick on but no sounds of trying to start. When it does start (at night or early morning), it doesn't sound too bad but it seems to make an extra effort before starting.
Check and diagnose in this order:

Cables, wires and their connections - loose, damaged, or corroded
Neutral Safety Switch - dirty or out of adjustment
Ignition Switch - possibly faulty
Faulty starter - starter should be removed and tested.

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post #5 of 5 Old 06-03-2020, 09:07 AM
Dale M.
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2002 TJ Wrangler 
 
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I had similar issue as a "no start" that the starter would not spin up when key into "start" position.... Found missing ground on terminal 3 of starter relay.....

Starter system is quite simple... Power from key (12 volts in start position) to one side of starter relay in main Power Distribution Center, relay winding (pin 5) and ground on other side of relay winding (pin 3) ... Contract (pins 1 and 2) of relay close to energies solenoid on starter.... You can jump pins 1 & 2 of relay to see if starter spins up (be sure you are in neutral) ... If it does, most likely you may have lost the ground on pin 3 of relay ... Power to solenoid through relay pins 1 & 2 come from a 40 amp fuse (#6) in PDC center to pin in relay socket...

This ground if manual comes from some point under vehicle through C154 on transmission and C104 under hood.... If you have auto trans it has neutral start safety switch if manual shift the ground is just a jumper between pins 1 & 3 of C154 and should supply standing ground at C104 (pin 5) to pin 3 of relay socket...

My issue Is I lost the ground coming from C154 on transmission (and its a bear to access as it is on top of trans behind shiftier) .... My fix was to splice in solid ground to pin 5 of C104 (fender side)

Simply a test lamp in pin 3 of socket should validate a standing ground and when key into start position should validate 12 volt at pin 5...

Dale
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Last edited by Dale M.; 06-03-2020 at 09:33 AM.
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electrical , heat , start , starter , wiring

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