Jeep dies at first start, then runs fine...NEED HELP!!

[Fergie]

SO this problem has only begun in the last week or so. It hasnt been to any shops, done any wheeling, or had any engine work done.

When I start the XJ after it has sat overnight, or over a long enough period of time for the engine to cool off, it has an idle problem.

It turns over quickly, just like usual, but dies instantly, or almost instantly. if I tap the gas, the idle will dip to almost dead, and then go to normal, but a little rough. It will warm up just fine, and wont die again, but if I give it gas going in reverse, it will lag, and the same for trying to go forward, but I let off the gas, and press again, it will be just fine. Any other starts when the engine is warm are just fine.

This is a 1995, 4L, 231, AW4.

Can someone please give me a list of things to start checking as plugs, rotor/cap, wires are all good. I am going on my honeymoon on Sunday, and need the XJ working perfect as we will be taking it all over CO. Thanks for the help!

Fergie

[Dr. Dyno]

The problem sounds like it might be a faulty check valve in the fuel tank. Check the fuel pressure at the injector rail after the vehicle's been sitting around for a while and if it's a lot less than 30psi (with vacuum connected), you've found the problem.

[Ed in North Ga.]

my 89s do that- I do the simple cure of doulbe primeing -
turn key on, listen for the pump to come on, then go off-thats supposed to mean the pressure is up to spec- Then I rotate the key again, pump will hit again, when it shuts off the second time, she starts right up.

It only does it after shes been sitting, an cold like yours. When its hot, you can try double primeing, and the pump wont come on the second time.
Ive thought about digging into it, but as long as this works, I dont bother...seems to run fine. Been doing it for a few years now. I never have checked the pressure on a cold morning with a single key turn..might do it for kicks now.

[skipc]

Could it involve the ballast resistor? Does it have one in that year? Maybe short around it to give the pump full voltage all the time.

[Fergie]

I have never dealt with any fuel pressure related problems. How do I check the pressure, and what job specific tools would it require?

I will also try the double priming.

Thanks

Fergie

[Fergie]

So I dont have this problem anymore, and the only thing I have changed is the place that I fill up at. I had been filling up at a local place, and when I went back to the another place that I usually filled up at, the hard start no longer exists.

Would gas from different places cause this type of situation?

Thanks

Fergie

[skipc]

It could have been water in the gas, or an odd formulation. I have noticed on mine, which starts fast compared to the reports here, that if I add one of my favorite additives - Berryman's B-12 Chemtool - that it starts in half the time and seems to run better, being more volatile. Less volatile would make it worse, as you were probably seeing, but if you get that gas again you might want to try that additive to compensate.

The better running when warm would be because it's more efficient about using fuel when warm, has more headroom for richening the injectors and O2 sensor feedback to say when. It also recirculates the fuel, so unless you get a large amount of water, it doesn't completely die.

Glad it's working.

BTW, never get gas while a fuel truck is unloading at the station. You will get bad gas for sure that way.