• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

1991 Cranks, Fires, then dies.

Jam Master Jay

NAXJA Forum User
Location
Broken Arrow
I'm trying to revitalize a sweet 1991 Cherokee Briarwood. It was running beautifully but after being left for a couple weeks without running it has started a new issue.

When I turn the key it cranks normally, fires off, then dies. It does that each time the key is turned. Giving it throttle can make it run maybe a half second longer.

I have changed the ballast resistor as well as jumpered it.
I have swapped around the fuel pump relays.
Neither changed anything.
I can hear the fuel pump kick on for a second when the key is turned to "on" each time.
There is fuel in the rail. I don't know the pressure but I am going to order a gauge.
The battery is fully charged.

Now for the weird part - I'm not new to XJ's so I immediately thought it could be the Crankshaft Position Sensor so I ordered a new one. In order to install it, I pulled the XJ forward about 20' with my truck. When I tried one more time to start it before changing the CPS it started normally.
Since I had the CPS I went ahead and changed it as a precaution.
After changing it, I tried to start it again and again it started and ran normally. I even took it for a brief drive in the neighborhood. Then I parked it again.

Now it is back to not starting like it had before.

It has a new fuel tank, fuel pump, and fuel filter that I replaced within the last year when I initially got it.

This is my second XJ. I also have a 1990 that I've had for over 25 years. It has a 4.6L stroker in it and is lifted and locked.
This '91 Briarwood was acquired from a friend and I plan to keep it completely stock, if I can ever get it to run reliably. I already deleted the original, terrible ABS system and replaced the alternator in addition to the above work.

Any ideas are greatly appreciated.
 
I know it sounds dumb but have you cleaned your battery terminals?

I had an XJ running good, let it sit for a while. When I went to sell it, it ran really rough and guy tried to lowball me for it. I couldnt figure it out. Later that day I cleaned the terminals and bam, ran like a top.
 
I have a fuel pressure gauge in order. I’ll check that this week.

I will probably go ahead and order a throttle position sensor. I’ve replaced several other sensors but that one is probably due too.

I will clean the battery terminals and make sure they’re good and tight. It’s been on and off a battery tender lately but I know one had been on and off a bit to save the battery.

I really appreciate the help. I’ll report back.
 
So I have a quick update. I checked my fuel pressure and it’s around 30-40 psi. I disconnected the throttle position sensor and it made no difference making me wonder if it is the problem. I got a replacement but in the course of trying to remove the old one I discovered that the screws holding the existing one must have been glued in and won’t budge so I drilled the heads out but I can’t get the studs out. I’m going to have to order a new throttle body.
I’ll post back once I’ve done that.
 
So I have a quick update. I checked my fuel pressure and it’s around 30-40 psi. I disconnected the throttle position sensor and it made no difference making me wonder if it is the problem. I got a replacement but in the course of trying to remove the old one I discovered that the screws holding the existing one must have been glued in and won’t budge so I drilled the heads out but I can’t get the studs out. I’m going to have to order a new throttle body.
I’ll post back once I’ve done that.


If you can't find a new used one, try heat around the base of the screws and vice grips. You'll want to remove anything from the throttle body that might be damaged from the heat.
 
So here’s an update- I got a used throttle body and installed a new throttle position sensor on it and put it on the Briarwood. It still didn’t fix the issue.
It still fires off and then dies.

Considering I have a new CPS, TPS, and sufficient fuel pressure, I’m stumped.
 
Bad ignition switch?
Run a jumper from the positive battery
Terminal to the positive coil connector
to verify. If it continues to run, the switch
iOS bad.
 
Clip your meter at the ballast resistor measuring voltage and try starting. That'll help determine if the fuel pump is losing voltage right after you let go of the key. Could be ignition switch or the starter relay on the passenger fender.
 
So it’s been a long time since I messed with my Briarwood just due to other things taking my time but I decided one day to go mess with it again and put in a fresh battery. I turned the key and held it down for several seconds and it started and ran. I’ll have to replace the switch but for now I’ll just use the long start method I guess.
I appreciate the help!
 
Back
Top