Jeep Won't Start

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  #1  
Old 01-01-04, 12:27 PM
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Jeep Won't Start

Happy New Year. I have a '93 Jeep Grand Cherokee with a 5.2 liter engine, auto transmission and about 120,000 miles. First problem was no rotation when trying to start. We tested the starter at a local parts store and it spun fine though the sales rep thought it may be a little weak (being $160 for a new one, I thought it was fine). We then tested the battery and replaced it due to a bad cell.

We now get the engine to rotate, but it won't start. Fuel seems to be fine as we are getting about 40 psi of pressure on the fuel rail and after pulling the fuel line off the filter, the pump is pushing a large amount of gas. I pulled two plugs and we are getting a good spark (the plugs were gapped at .057" instead of .035" as stated in my manual, but the car ran okay with this plug gap previous to this problem). I also replaced the oxygen sensor because of a trouble code, but that made no difference either.

What should I check at this point? Thanks for your help.
 
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Old 01-01-04, 03:14 PM
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OK, first point is you can't test a starter out of the car on the bench. That won't tell you much. Is it cranking fast enough now? Have you checked for injector pulse? Were the plugs fouled with fuel when you took them out? The oxygen sensor had nothing to do with the "no start" and probably had nothing wrong with it. Just because you get an oxygen sensor code doesn't mean the sensor is the problem. They are usually just indicators of another symptom. What was the code?
 
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Old 01-01-04, 03:56 PM
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The car seems to be cranking fast enough to start the car, but is there another test I can run on the starter without having to shell out the cost of a new one? Could the starter not be turning strong enough to start the car?

Can you please give me more information on "injector pulse" as I am not sure what you mean or how to test for it.

The two plugs I pulled out had a carbon deposit on them, but not what I would call fouled with fuel.

Before I had a starting problem with the car I was getting a trouble code of "52", which in my manual indicated a problem with the oxygen sensor. Because of where the wiring was around the exhause manifold, it was too tough to test and I decided to just change it.

I figured if I have fuel and a spark, that perhaps air was the problem. I pulled off the air duct and the throttle body looks clean. Any ideas are appreciated.
 
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Old 01-01-04, 06:52 PM
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Fouled with fuel means.... were the plugs wet with gas? How did you check for spark? Are you sure that you have sufficient spark? What happened just before the current no start condition?
Billy
 
  #5  
Old 01-01-04, 08:09 PM
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The plugs were completely dry with no fuel - only a light black carbon deposit.

To check the spark, I pulled the plug, plugged it into the spark plug wire and turned the car over. Both the plugs I pulled had a very strong spark between the electrodes and this is from comparison to cars I have worked on with challenged ignition coils.

From what I was told, the car was getting difficult to start and would take a few tries before it would start. When I started to work on it (my son's car), the engine would not turn over at all. That is when we bench tested the starter and replaced the battery due to a dead cell.
 
  #6  
Old 01-01-04, 09:56 PM
mike from nj
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you need two things to get fuel into the engine, 1- fuel pressure in the rail, and 2- injectors to spray that pressure where it's needed.

have you tried holding the gas pedal down all the way, or even 1/4 of the way down to help it start? often times a dead battery will screw up the idle air control motor's memory, and the pedal removes that variable.

how old are the spark plugs? were they set to .057" or did they wear out to that measurment. this wouldn't be the first or the hundreth time a car didn't start from a poorly maintained ignition system.

try removing the air filter housing and giving a good (5second)spray of something flammable onto the throttle blades. this may start it and would narrow it down to a fuel delivery problem

by any chance, did the battery go dead from cranking so long?

(if the plugs are less than 12,000 miles old, set the gaps back to original specs, you are overheating the ignition coil needlessly).


keep us posted
 
  #7  
Old 01-04-04, 04:25 PM
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I went back and checked all the plugs, which were in good shape other than the gap. I then checked the wires and after following them back, found the distributor cap had a large crack in it. I replaced the cap and rotor and the car now starts, but will only runs for a couple seconds and then stops immediately. I went back and checked the vacuum hoses I pulled off to get to the cap and a rechecked the firing order and all seems to be okay.

What direction can I go now? Thanks.
 
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Old 01-04-04, 05:02 PM
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Again, you need to find out what is dropping out the cause it to stall. Put a fuel pressure gauge on it and install a noid light to one of the injectors and monitor what happens. You could have a fuel pressure problem or it may even be the security system causing that. Do you have a security light and if so what is it doing?
 
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Old 01-04-04, 05:08 PM
toivo
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cherokee

check your fuel pump relay. have someone listen at the gas cap when you turn on the ignition switch and see if they can hear the fuel pump run for 2 seconds. if your fuel pump is ok then your ignition switch may be at fault when you release the key to the run position.
 
  #10  
Old 01-04-04, 07:32 PM
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Thank you for the replies. I checked by the fuel tank and when the key is turned on, we are getting a whirling sound for a few seconds, so I assume that is the fuel pump working.

Regarding the security system, I now find out (this is my son's car) that because the keyless remote does not work or is worn out AND because the security light was coming on, the fuse was pulled out to kill the alarm system. Could this be the reason the car is not starting???
 
  #11  
Old 01-04-04, 10:51 PM
mike from nj
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Originally posted by ellersk
Regarding the security system, I now find out (this is my son's car) that because the keyless remote does not work or is worn out AND because the security light was coming on, the fuse was pulled out to kill the alarm system. Could this be the reason the car is not starting???
if it has a 'factory' vehicle theft alarm (vta), you need to cycle the key in the driver's or passenger's door to reset the alarm (lock and unlock it). usually unplugging and replugging the battery sets off most alarms. there is no fuse to pull out, the vta is inside the main computer, and it kills the fuel injectors after 2-3 seconds(no thief can bypass this)

if it's any kind of aftermarket alarm, the car wouldn't crank at all(usually), but this can easily be defeated by a screwdriver on the starter terminals, it sounds like you don't have this though, but which fuse is pulled?

maybe the fuse was for the horns?

what does it say on the broken remote?
 
  #12  
Old 01-05-04, 08:56 AM
toivo
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jeep won't start

if the security sytem is factory you will need to get a new remote or find out how to put it in bypass mode, if it has one. if it is aftermarket you can probably remove it but you have to put everything back the way it was, i.e. [ solder wires together again or find out who installed it and take it back, or get a new remote from them. or find out how to put that in bypass.later, toivo
 
  #13  
Old 01-05-04, 08:10 PM
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Car is back running!!! Thanks for your help as it was indeed the alarm system. The fuse that was pulled cut off the flashing lights and horn. We bought a couple new batteries for the remote, put the fuse back in, turned off the alarm and turned the key. Car runs great and all it cost me was a new battery, cap and rotor, which it needed anyway. Again, thanks for the great advice.
 
  #14  
Old 01-06-04, 07:36 PM
mike from nj
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awesome--glad it's fixed

thanks for being the one in a hundred people who writes back with the actual fix.
 
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