I have a '97 XJ with 300k miles on it. It's stock, bought it a few months ago, and everything is in good shape for its age. It ran fine up until a few weeks ago.

It will start and drive just fine from cold. I'll drive it a few miles down the road to the store, for example. When I get back in to start, it will just crank and crank. It will take forever to start, but eventually will.

Without fail I'll get about a mile down the road and it will stall out. It usually happens when I accelerate from a stop. I'll feel it stumble for a quick second and die. If I get lucky, I give it a shot of gas and it won't die (but eventually will shortly down the road). I'll have to crank and crank and crank some more. Usually let it sit for a minute or two, stuck in the road, and eventually it will fire right up.

I haven't been through this rig very much besides a look over and fluid changes. I'm not sure what the previous owner had replaced or not. I just took off the throttle body, cleaned it, new gasket, and tested the throttle position sensor with a voltmeter (it was fine).

Some have said heat soak, but I'm not getting indicators of overheating (I have the temperature light, not a gauge so I can't see if it's running hot anyways). The ambient temperature has been about 50 - 60 degrees. I heard another person say it could be a leaking injector, and recommended I press the accelerator to the floor next time I restart it from a stall.

What does the knowledge of the forum think? Thank you!

 

97 aren't very prone to heatsoak.

I know you said you haven't got much info about previous work, but do you know if the CPS has been done at all? It's def on the list.

It would be helpful to know when you have (warm) hard starts, if and what the fuel pressure is.

 

[QUOTE=Roler;3707297]97 aren't very prone to heatsoak.I finally got around to checking the fuel pressure. Fuel pressure was about 49 psi at idle (service manual says 49.2 +- 5 psi, so it was in spec). I shut it off, PSI dropped to about 48, then held steady for at least 5 minutes after shut off.

So it passed a fuel pressure and leak down test.

I checked all the spark plugs. They all looked the same: old and carbon fouled. I replaced them all, gapped to .035.

I checked the wires at the plug and distributor: they all looked good and had a positive click when seating.

I popped open the distributor. The cap and the rotor looked good. The rotor seemed fairly new; I cleaned it up with a wire brush and cleaned it off just to be sure.

Injectors seemed good: resistance was all within proper range and they're mechanically operating as they should (I used a mechanics stethoscope).

I cleaned the throttle body and replaced the gasket, changed the air filter, cleaned all of the connectors on the throttle body, checked the throttle position sensor with a multimeter (good voltage up and down the range of the throttle blade), etc.

Crankshaft position sensor is brand new.

The battery is brand new and all the connections are clean and tight

The problem still persists! I'm not sure where to turn next. I will get a hard start about 90% of the time after it's been running in the driveway for even just a few minutes. It won't start unless I turn it back off and crank it again. It will start about 65% of the time on the second crank. It will start real rough, like it's about to die, and I'll give it some gas and it will even back out. I watched the fuel pressure gauge when I've got this hard start and it jumps up to about 50 PSI, so the fuel rail is getting gas when it should.

Any suggestions?

 

Got a scan tool w/live data? Or the parts store, get some data. Information is key!

 

No scan tool. I wish I had one!

I removed and tested the ignition coil. I got 1.3 ohms primary resistance, and 11,530 ohms secondary resistance.

I don't know what brand the coil is, but either way it seems out of spec on primary resistance per the service manual.


I'll replace the coil and see what happens.

UPDATE

The new ignition coil tested within the same range as the old, and it still didn't fix the issue. Which makes me think the old coil is good (my cheap multimeter is just off by a tad).