cranks but doesn't start

bradleyheathhays · Sep 5, 2019

So I got this '96 Jeep Cherokee XJ that cranks but doesn't start. It's got around 180k on her but I keep everything in good shape. Batt seemed strong.

I used to drive it everyday but this past year I've driven it only about twice a week. It's been just slightly slower to start in the last couple of months, but just barely slower. Was guessing it had something to do with aging plugs or something.

Drove it yesterday and everything was normal like always, sat overnight and today it cranked but didn't catch.

Any ideas on where to start?

4x4Phil · Sep 5, 2019

Hi sorry to hear you're having issues. I have a 96 also and drive about the same in the past year and had the same issue. Replaced the CPS and the spark sensor. Did the trick. I was getting plenty of fuel, pressure in the rails but no spark.

Hope that helps. Both are super easy to swap out.

Sent from my Pixel 2 using Tapatalk

Down under · Sep 5, 2019

Try getting someone to jump start you, and see if it first up better. If so, cranking power in your battery is gone.

Down under · Sep 5, 2019

Oops "fires up" better.
Got to work out how to edit!!!

Anak · Sep 5, 2019

A jump is a good idea for a simple check.

How does the inside of your distributor look?

What is your fuel pressure?

Check both spark and fuel pressure. That is the starting point. Once you confirm both of those then you can start to worry about things like the CPS.

bradleyheathhays · Sep 6, 2019

Thanks for all that good advice.

So far I've been able to run a couple tests..

Hooked up a fuel pressure gauge and first key turn got it up to only 20psi. Second turn got it up to 45. And third and subsequent turns got it up to 48. It only fell to 43 after 2 minutes so I think that means the fuel pressure is good.

Hooked up a spark tester between a plug and wire and it didn't light at all when cranked so I'm guessing I've got a spark problem. I'll start by doing a tune up with new rotor, cap, wires and plugs then see what happens. After that it sounds like I need to go with the CPS and spark sensor like Phil suggests.

4x4Phil · Sep 6, 2019

bradleyheathhays said:
Thanks for all that good advice.

So far I've been able to run a couple tests..

Hooked up a fuel pressure gauge and first key turn got it up to only 20psi. Second turn got it up to 45. And third and subsequent turns got it up to 48. It only fell to 43 after 2 minutes so I think that means the fuel pressure is good.

Hooked up a spark tester between a plug and wire and it didn't light at all when cranked so I'm guessing I've got a spark problem. I'll start by doing a tune up with new rotor, cap, wires and plugs then see what happens. After that it sounds like I need to go with the CPS and spark sensor like Phil suggests.

I keep a spare of each in the Jeep as they such common culprits. There are tests to determine with a multimeter if they are good but honestly if it's been a while it's just easier to swap them out.

Sent from my Pixel 2 using Tapatalk

Anak · Sep 8, 2019

bradleyheathhays said:
Thanks for all that good advice.

So far I've been able to run a couple tests..

Hooked up a fuel pressure gauge and first key turn got it up to only 20psi. Second turn got it up to 45. And third and subsequent turns got it up to 48. It only fell to 43 after 2 minutes so I think that means the fuel pressure is good.

Hooked up a spark tester between a plug and wire and it didn't light at all when cranked so I'm guessing I've got a spark problem. I'll start by doing a tune up with new rotor, cap, wires and plugs then see what happens. After that it sounds like I need to go with the CPS and spark sensor like Phil suggests.

That sounds like a reasonable plan.

After you take care of the spark issue (and hopefully have it running) I would give a thought to the fuel filter. How long has it been since it was replaced? Only reaching 20psi to start makes me question how well your filter is flowing/how hard your pump is having to work.

Bent · Sep 9, 2019

Not to be "that guy" but you really ought to try posting these threads in the tech forums. I think you'll get a more targeted response than in the off-topic / non-tech forum.
https://www.naxja.org/forum/forumdisplay.php?f=44

Just saying.

cranks but doesn't start

bradleyheathhays

NAXJA Forum User

4x4Phil

NAXJA Forum User

Down under

NAXJA Forum User

Down under

NAXJA Forum User

Anak

Stranger

bradleyheathhays

NAXJA Forum User

4x4Phil

NAXJA Forum User

Anak

Stranger

Bent

Only Marble Sharp

Similar threads