About to buy a 97 XJ, have a few questions.

I am about to buy a 97 XJ, 4.0, auto with 142K on the odometer. The owner is a friend and has owned it since 2002. I went and test drove it toady. It cranks longer than what I think is normal before it starts when the engine is cold. The owner said he put a fuel pump in it. Sounds like a fuel pump to me? Second, it runs rough when cold. The CEL is not on. It runs pretty good when the engine gets up to operating temp. Any ideas? Thanks!

might be losing pressure in the fuel rail when it sits

H8PVMT said:

might be losing pressure in the fuel rail when it sits

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Yes. I have been doing some research since I started this thread. I plan on checking the injectors also.

For a quick check of fuel rail pressure loss, turn the ignition on, wait about 5 seconds, then crank. If it starts faster, you have some leakdown, but really no worries for actual running. If it starts a little faster, but not fast enough, try turning ignition on, wait 5 seconds, turn off, turn back on, wait another 5 seconds, then crank. That should pretty much take care of even a total leakdown, such as you'd get if you'd opened a fuel line or bled off the pressure to do a repair. If it still takes too long to crank, you might want to look for problems elsewhere.

I've never worried about this as long as I know it's fuel pressure leaking down. It's probably even better for the engine to crank a little longer on a cold morning.

new plugs & distrib cap / rotor

Well I bought it!:thumbup: I put a fuel pressure guage on it and it dropped as fast as it primed. I pulled the fuel rail off with the injectors still attached and primed it to check for a leaking injector. All injectors are good and no leaks. So , I figured the fuel pressure regulator was leaking. Regulator = $100, the hole sending unit with regulator = $180, so I went ahead and replaced it all. Started right up after priming and held 46 psi with the engine off. I am going to check it again in the a.m. but I think it will be good. Thanks for the replies everyone!

Very common on a '97 to have a fuel pump "check valve" issue, which leads to quick fuel pressure drop, which leads to an extended crank time.

The check valve is in the regulator, so replacing that unit should have taken care of this problem!