Originally Posted by nemanjaguitar

what about the oil that occasionally goes through the hose? would that damage the hose?
Thanks

Originally Posted by ZachsXJ

Over time, maybe. It'll take many months ifnot years before that would become an issue.

Originally Posted by Teloca

I have a couple of exhaust system questions:

1) I am thinking about installing an exhaust header on 99 XJ 4.0. I did not think this was going to be a big deal but the more I look at it it looks like you have to pull the intake manifold off to do it. Just wanted to ask some of you guys who have done it before....is there an easy way to get the old exhaust manifold off and new header in without taking the intake off?

2) Also I noted that about 8" from the flange on the exhaust pipe it looks like the pipe is partically crushed is that standard...it looks like maybe the front drive shaft hit it but I can't see how (or maybe it is there to keep the drive shaft from hitting? Is this some std restriction for back pressure and can it be removed to improve performance?

Originally Posted by nemanjaguitar

Thanks man. That makes me feel better.

Originally Posted by Teloca

Regarding the Exhaust Header vs. intake manifold....I was afraid you would say that .....

Anybody know of a good header that will improve performance with out costing and arm and leg? And a high flow cat taht works well for Jeeps?

Regarding the exhaust pipe restriction...I think I will just take it out and repipe it so all the pipe is the same size all the way back (don't know why jeep uses different size exhaust pipes in front of the cat).

Originally Posted by Teloca

Regarding the Exhaust Header vs. intake manifold....I was afraid you would say that .....

Anybody know of a good header that will improve performance with out costing and arm and leg? And a high flow cat taht works well for Jeeps?

Regarding the exhaust pipe restriction...I think I will just take it out and repipe it so all the pipe is the same size all the way back (don't know why jeep uses different size exhaust pipes in front of the cat).

Originally Posted by thundaluvin

Anyone know if my 97 4.0 will fit in my 88? if so, is it direct or do parts need to be kept off the old motor? Thanks in advance

Originally Posted by ZachsXJ

It'll fit, but the fuel rail, throttle body, ECM, a few sensors, the head, cam and some other stuff are different.

I'd try to find a motor from an 88-90 XJ.

Originally Posted by thundaluvin

Much obliged. Guess ill be hitting picapart this weekend. dam snow! my jeep NEVER breaks down in the summer, always winter.

Originally Posted by dukie564

Also, when a 1997 to 2001 Cherokee won’t start on the first try day after day, the first thing to suspect is a failed check valve on the fuel pump. It is an EXTREMELY common issue on your year cherokee. The fuel pump check valve is supposed to hold pressure in the fuel line while the engine is off. The check valve is located on the fuel pump and located in the gas tank. A failed check valve allows the fuel to drain back to the tank. This results in the following symptoms:

SYMPTOMS

· Longer than normal cranking times
· Never starts on first try, almost always starts on the second try
· Rough idle for a few moments of idling
· Rough running for first ½ block of driving
· Little or no fuel pressure at the fuel rail test valve similar to this -

1- Key in on position; fuel pump primes for 2 seconds then stops. 0 PSI
2- Cranking over the engine. 2-3 PSI
3- Engine starts and idles for 20 seconds. < 5 PSI
4- Engine idles and fuel pressure creeps up to 45 PSI.


POSSIBLE CAUSES

· Failed check valve on the fuel pump in the gas tank.
· Leaky fuel injector(s) may be the true cause of your problem, but more likely they are simply contributing to the check valve issue.

Testing of the fuel injectors should show if any are faulty and are allowing fuel to drain into the cylinder. Either problem can allow heat soak to vaporize the remaining fuel in the fuel rail and you may be dealing with a bit of vapor lock as well, especially in warmer weather.

1. Connect the gage at the fuel rail and start the engine. The gage should read 49 psi plus or minus 2 psi.

2. Turn the engine off and immediately clamp the fuel line just ahead of the fuel tank. Watch the pressure gage and see how long it takes to loose pressure.

If the pressure remains at 49 psi for an extended period of time then the problem is in the tank - probably the check valve. If the pressure falls below 49 psi fairly rapidly then the problem is probably a leaky injector.

There are a few solutions to the problem –

1. Turn the key to ON for 5 seconds and let the fuel pump prime. Turn the key to OFF, turn the key back to ON for 5 seconds, start the engine.

2. Crank the engine for 3-5 seconds, pause, and crank the engine again. It will almost always start on the second try.

3. Replace the fuel pump assembly in the gas tank. The check valve is not a separate part and cannot be serviced. This is both expensive and time consuming because you have to remove any hitches and skid plates and then remove the gas tank from the vehicle.

You can use solutions 1 or 2 for as long as you want to, they do not harm anything and the fuel pump will continue to function for many more years.


If you do replace the fuel pump assembly, purchase a high quality OEM style unit. Some cheap aftermarket assemblies, like Airtex, don’t hold up and fail completely within 12-18 months. .