Spoolproof

Hey guys,
So this is my first post I'm new to this forum. So I need help with a issue I'm having with my jeep and first off I'm letting you all know I have searched the internet and forums high and low for a solution for my problem and have not yet found one.

To start I drive a 1992 jeep Cherokee (xj) 4 door auto transmission it has the 4.0 HO motor in it. Last Sunday I went to start it and it would turn over but not fire up. I replaced the fuel filter and it happened to fire right up and run normal all day with out a problem. Then the next day I go out to start it in the morning and same thing it turns over and will not fire up. Since then it has been a week of not having my daily driver and I have been searching for solutions and replacing suspect parts. In total I have now replaced all these with new parts. Spark plugs, distributer rotor and cap , new msd ignition coil, new crank position sensor, new 02 sensor, new water temp sensor, new throttle position sensor as different forums suggested some of these parts for similar problems. I have also done fuel pressure tests and the numbers are coming out to the proper specs and my Haynes manual suggests. After replacing all these parts and doing test with no success yet I have found that it will not fire up, but if I pull the fuel pump fuse it will idle just fine. Then as soon as I plug the fuel pump fuse back in it just floods again and stalls. So I'm not sure what is causing the flooding situation. Any help would be great as this is my daily driver.

jake92

Check the fuel pump ballast (sits on the left side near the cowl) also check wiring and connections for short to power

RTorrez1

Before throwing more parts at it. Where did you get you new cps from? After market are known to be bad right out of the box. You want an OEM one. Also I would get rid of the MSD coil the are also over rated. You would be better off with a standard OEM type coil. You said that you check the fuel pressure? For you year you should have at least 39psi + or - 5psi. Also make sure that you have a good blue spark. Any other color isn't good enough for the 4.0.

kjc

You said "After replacing all these parts and doing test with no success yet I have found that it will not fire up, but if I pull the fuel pump fuse it will idle just fine. Then as soon as I plug the fuel pump fuse back in it just floods again and stalls." A little confusing It won't start, but idles fine? I'll assume it does start now but floods when you plug in the fuel pump fuse? My '93 has a fuel pressure regulator up by the fuel rail. If yours does, you might check that out. Good luck!

Spoolproof

I will check the ballast. And electrical wires and connections. The ballast is just to make the fuel pump quieter right? The cps is "BWD" brand there supposto be good parts. And for the fuel pressure regulator it tested out ok when I tested how the Haynes manual says to test it.

Spoolproof

Ok so last night I looked at the fuel resistor ballast and pulled off both wires that connect to it and the terminals were pretty dirty so I wire brushed them to make sure it connects good. Also pulled out the (IAC) idle air control and cleaned it. And fixed a leaky pcc hose at the back of the valve cover. ( on a side not that Pcc hose has been leaking since way before I bought the jeep do it shouldn't have been causing it not to run but the hose is fixed now reguardless. And now my jeep starts right up, idles, drives. I test drove it around for a hour today. It seems to drive good. It seems to have a slight miss fire at idle or a slight rough idle so I'm not sure what is causing that but at least it runs again.