I picked up a 97 XJ Sport a couple of weeks ago. 4.0L, 4x4, 5-speed manual, with around 162,000 miles.

It ran fine for the first week, though at times it took quite a bit of cranking to get it started. I assumed the problem was the battery, because the Jeep had been sitting in the previous owner's driveway for 6 months with little to no use.

Then, about a week after I got it, I attempted to start it, and instead of a crank, I heard a "clunk" sound when I turned the key over. Came back 5 minutes later, and it would crank, but not fire up.

I went ahead and installed a new battery, because even if this wasn't the cause of my problem the thing probably should have been replaced anyway. With the new battery in, I got a strong crank but still no start.

On the advice of a friend I tried giving it some gas while cranking. It started up immediately, and ran just as well as before this issue began. I drove it about 90 miles after getting it started, and it ran excellent. I got good gas mileage (20+ mpg average) and good power. It idles fine, too.

Again, on the advice of a friend, I put some injector-cleaner additive into the gas tank. Now, sometimes I have to pour in throttle to get it to start, and sometimes it starts right up without any hesitation.

When the XJ won't start without throttle, I have tried the "poor man's prime" method described on this forum to diagnose a possible check-valve issue, but this does not work in my case.

I'm thinking this is a fuel supply issue of some sort, possibly caused by gunk build-up over the 6 months the XJ was sitting, but it runs so well after it starts that I'm not sure. Any ideas? Could it still be the check-valve issue?