'97 TJ doesn't start on occasion

JR14

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Joined
Feb 23, 2019
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Murrumbateman NSW
Hi Guys, Im new to this site but not to Jeeps having had CJs, TJs and a new Cherokee Trailhawk last yeat.
Im hoping someone here might be able to help with a non starting problem which happens occasionally. I have an issue with my current TJ where every now and then it decides it aint going to start. It cranks, has plenty of battery juice, was going fine five minutes ago but refuses to play the game when I try to restart it. On one of the posts here I read that a member said to pull the plug on the coil, wait a bit then reconnect it. So I did, and it worked...each time it does it, this is the solution. Unfortunately he wasnt aware of what this actually does or why it works. Nor am I.
Any ideas?? Should I be replacing the coil? Bit of an odd one. Thanks in advance.
Jeff
 
Hmmmmm.
Are you disconnecting the input side (to ignition) or the output side (spark plug wire to ignition) to fix it?
Check to make sure the connections are tight and, maybe add a bit of dielectric grease.
 
Hmmmmm.
Are you disconnecting the input side (to ignition) or the output side (spark plug wire to ignition) to fix it?
Check to make sure the connections are tight and, maybe add a bit of dielectric grease.

Thanks TJ.....the input plug. Not the output to the distributor. Both have good connections....he says semi confidently. But why would it work one day then on a whim it decides not to?
 
If it's an intermittent connection issue, that could cause it. Is there any sign of corrosion on either the coil or harness side of the connection? Again, a dab of dielectric grease and several plug/unplugs to help clean the contacts might do wonders.
 
I’ve seen the cpssensor do this on xj’s id suggest you pull and test that, most folks recommend the Mopar replacements
 
I’ve seen the cpssensor do this on xj’s id suggest you pull and test that, most folks recommend the Mopar replacements
CPS sensor replaced recently with an OEM unit. I learned the hard way by buying a cheap ebay sensor and ended up having to do the job twice. No, that should be fine but thanks for the suggestion.
 
It's either a fuel or spark problem, I suspect a spark problem like perhaps your ignition coil is going bad. Try to isolate it to fuel or spark. The next time it won't start see if you're getting spark to your spark plugs... you know how to do that right? You can also spray starting fluid into the throttle body to see if it starts then, which would indicate an intermittent fuel pump or fuel pump circuit.

You can also attach a fuel pressure gauge to the Schrader fitting on your fuel rail when it won't start to see if it has the at or very close to 49 psi pressure. The Schrader fitting is like an oversize tire valve stem.
 
It's either a fuel or spark problem, I suspect a spark problem like perhaps your ignition coil is going bad. Try to isolate it to fuel or spark. The next time it won't start see if you're getting spark to your spark plugs... you know how to do that right? You can also spray starting fluid into the throttle body to see if it starts then, which would indicate an intermittent fuel pump or fuel pump circuit.

You can also attach a fuel pressure gauge to the Schrader fitting on your fuel rail when it won't start to see if it has the at or very close to 49 psi pressure. The Schrader fitting is like an oversize tire valve stem.

I had the same thought so I pulled a plug, cranked it and there was no spark. Hence my replacing the coil question. I think perhaps I'll try that and see if that makes a difference.
 
No, I dont have gear to do that unfortunately.
Yes you do, it's built into your '97. Only 98-99 models don't have that built-in ability. Turn your ignition switch on-off-on three times within five seconds and then leave it in the On position. Within several seconds any codes that are present will start displaying in your odometer. If you did it correctly you'll at least get a '55' code (end of codes) and usually a '12' code first to indicate the battery has been disconnected in past history.

http://www.allpar.com/fix/80s-codes.html
 
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Yes you do, only 98-99 models don't have that built-in ability. Turn your ignition switch on-off-on three times within five seconds and then leave it in the On position. Within several seconds any codes that are present will start displaying in your odometer. If you did it correctly you'll at least get a '55' code (end of codes) and usually a '12' code first to indicate the battery has been disconnected in past history.

http://www.allpar.com/fix/80s-codes.html
Thanks Jerry...I'll try that today.
 
It's either a fuel or spark problem, I suspect a spark problem like perhaps your ignition coil is going bad. Try to isolate it to fuel or spark. The next time it won't start see if you're getting spark to your spark plugs... you know how to do that right? You can also spray starting fluid into the throttle body to see if it starts then, which would indicate an intermittent fuel pump or fuel pump circuit.

You can also attach a fuel pressure gauge to the Schrader fitting on your fuel rail when it won't start to see if it has the at or very close to 49 psi pressure. The Schrader fitting is like an oversize tire valve stem.

It's either a fuel or spark problem, I suspect a spark problem like perhaps your ignition coil is going bad. Try to isolate it to fuel or spark. The next time it won't start see if you're getting spark to your spark plugs... you know how to do that right? You can also spray starting fluid into the throttle body to see if it starts then, which would indicate an intermittent fuel pump or fuel pump circuit.

You can also attach a fuel pressure gauge to the Schrader fitting on your fuel rail when it won't start to see if it has the at or very close to 49 psi pressure. The Schrader fitting is like an oversize tire valve stem.



I wanted to jump in here if can and ask for advise on a similqr issue

I am having an issue with my 02 tj 4.0.
it has no fuel pressure when you turn on the key, starts when cold after few cranks but when its warm it will crank and fire only briefly. if you crank long enough and wait long enough it finally starts and runs rough idle then smooths out, at this point it only has about 25 psi fuel pressure

have new fuel pump and sending assembly and new injectors installed

this one got me searching for an solution

thanks