Jeep turns over but won't start. What first? - JeepForum.com

 
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post #1 of 8 Old 02-05-2007, 04:29 PM Thread Starter
zeketorrence
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Location: Gainesville, GA
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Jeep turns over but won't start. What first?

My jeep turns over but won't start (93 ZJ 5.2 136k). Started first time everytime until yesterday and out of nowhere this happened. So far, I replaced the battery (planned on it anyway). What should I check first? I don't smell gas so I'm wondering if it's fuel related. Anyone know what I should check first?

Edit- there are no codes (except code 12 for battery being disconnected)




'93 ZJ Limited 5.2 4x4
2"BB, ProComp ES3000 shocks
31x10.50 Dueler AT Revo's
Zacatel roof rack w/Hella Fog lights
Full factory skids. 136k
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post #2 of 8 Old 02-05-2007, 04:31 PM
greasefingers
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Guide to Engine No Start Issues
Engine will not start but does crank-over.
The term “cranks-over” means that the starter motor is energized and turning the flywheel/engine but there is no combustion.

You must identify if the problem is spark or fuel related.

1- If you have an alarm, make sure it is de-activated.
2- Make sure that you have fuel in the gas tank.
3- With the engine off turn on the headlights for one minute. Wait five minutes and measure the battery voltage. The battery voltage should be at least 12.6 verifying that the battery is good could save you some time here.
Pull the codes from the computer.
4- Turning the ignition switch on, do not start the engine; check for the engine light on the dashboard to go on and then off. This means that’s the PCM has received power. At the same time, listen for the fuel pump. Does the fuel pump make a whining noise?
4a- check the Trans. Cont. Mod./Ignition. Fuse in the PDC
5-Now check for spark by disconnecting the center post distributor cap wire. Hold it close to ground about 3/8 inch away (the cylinder head will do) while someone tries to start the engine.
If no spark then I would measure the primary & secondary coil resistances. If OK then I would replace the crank sensor.
6- If replacing the crankshaft sensor did not help or it did not ever start then you have to work backwards and find the last place that battery was supplied. You may only have three seconds for each check, as the ADS relay can be timed-out.

Notes: The next most common electrical failure after the Crank sensor is the camshaft sensor and the coil.
After three seconds if the PCM does not receive an input signal from Cam & Crank sensors, then the PCM will not allow the coil to fire or permit battery to the injectors.
-----------------------------------------------------------------------------------------------------------

If you have spark, then it is most likely fuel delivery.
If the vehicle has an external fuel filter, then change it. Drain some of the gas from the inlet end of the filter into a glass jar. Check the color and look at the bottom of the jar for water & debris.
Turn the ignition switch to the Run position only (not the Start position). Listen for the fuel pump motor to make whining sound in the gas tank. If you have a fuel pressure gage, then check for approx 30 to 40 psi at the fuel rail. If you hear nothing then disconnect the electrical connector, at the tank, and check for a 12 volt supply coming from the engine end of the harness. If 12 volts is present then check for continuity across the fuel pump. If no resistance or mega-ohms, then the fuel pump motor is most likely dead. If so then drop the tank and replace it.

If none of the above helps then the PCM/ECU could be at fault.
I am not a professional mechanic, so try the above at your own risk. The above are guidelines only. Work safely. Electrical systems can be “live” without the key turned on. The fuel system is pressurized, even after the engine has been shut off. Please fell free to correct errors that you may find. Good Luck!!

Cheers Steve

94 Black Laredo 4-Liter with QuadraTrac (42RE trans & NP249 TC) 200,000 + miles purchased new

88 Cherokee 2-door with 5speed manual 139K miles(deceased) purchased new
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post #3 of 8 Old 02-05-2007, 05:57 PM
ras2001wj
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Quote:
Originally Posted by greasefingers
2- Make sure that you have fuel in the gas tank.
if this is the problem, i would shoot myself

Rick

2001 WJ Laredo 4.0
2" BB
245/75R16


Ron Paul
2012
"Freedoms Popular"
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post #4 of 8 Old 02-05-2007, 06:08 PM Thread Starter
zeketorrence
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Ok- my fuel pump is dead silent. Can they just completely die out of the blue?

'93 ZJ Limited 5.2 4x4
2"BB, ProComp ES3000 shocks
31x10.50 Dueler AT Revo's
Zacatel roof rack w/Hella Fog lights
Full factory skids. 136k
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post #5 of 8 Old 02-05-2007, 06:34 PM
greasefingers
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My fuel pump died while I was driving it. It just quit and I coasted to a stop. But the day before, the engine back-fired twice while driving at a constant high speed.

Cheers Steve

94 Black Laredo 4-Liter with QuadraTrac (42RE trans & NP249 TC) 200,000 + miles purchased new

88 Cherokee 2-door with 5speed manual 139K miles(deceased) purchased new
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post #6 of 8 Old 12-29-2009, 10:18 AM
Genericusername
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Location: Middle of America
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so when i got to check the spark i pull a cord similar to the other end of the spark plug and put it close to what? to check for a spark?

1997 ZJ 5.2L V8 256,000 miles "Fart" http://www.jeepforum.com/forum/f22/welcome-zj-fart-751053/
Quote:
Originally Posted by m_amilli View Post
by the thing that spins when you drive underneath
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post #7 of 8 Old 12-29-2009, 12:28 PM
baxy
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out of fuel is very common here
for a long time shell fuel had an additive which reacted with the card for the fuel sender coating it in black crud
the gauge would show 1/4 tank but tanks were empty
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post #8 of 8 Old 05-27-2011, 03:03 PM
jeepchick123
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Hey, So I'm having similar issues with my 1989 Cherokee. It started like normal when I headed to work for the day then when I tried to start it to head home my engine just kept turning over. I'm not a car person so I got my friend's Dad to look at it. They thought it was the fuel pump but tested that and it works. They've checked for sparks and things too... Anyone have any other ideas to contribute to a young girls cause? Haha
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