I swear I hear the fuel pump humming in the tank while the Heep is running? I have a 1990 4.0 Aw4 NP242 and is just hummmmssss. I get plenty of fuel and everything just hummmmss not sure if this is normal or means the pump is going to die soon. also how hard is it to replace the gaskets in the HEEP head gasket, exhaust gasket and valve cover gasket??? is it a PIA. or is it doable?

 

Usually this would mean the pump is going out... however mine has hummed for the 2 yrs I have owned it and the previous owner said for the last 2-3 yrs he owned it. Crawl under your Jeep, though I have never replaced a fuel pump on an XJ is looks way too easy. It is right on the front of the tank. Better than most vehicles where you have to drop the tank to get to the pump on top.

Gaskets... I wouldnt bother with the head unless you think it is blown.. it would be using coolant and overheating. The valvecover is one of the easiest to do. The intake/exhaust (same gasket) isnt too awfully hard, just quite a bit to unbolt.

 

It is quite normal for fuel pumps to make a little humming noise. If it is getting noticeably louder then it could mean that your pump is on its way out.

Head Gasket - Not too difficult to replace as long as you have a good manual and some half decent wrenching skills. More time comsuming than anything though. As said above though, make sure its blown or leaking. There's no sense in doing it "just 'cause".

Valve cover gasket - Easy.

Exhaust gasket - Assuming you mean the manifold to head gasket, not too hard in theory but be careful as the bolts/studs get quite rusty and break fairly easily. PB Blaster is your friend.

All in all, it pays to get a good manual and do some research before just diving in. If you think you can do it after reading up on it, you probably can.

 

Hi, I replaced my fuel pump twice this week. The hardest thing was loosening the securing ring on the lock of the sending assembly. Made me a brass hammer and punch so as not to get any sparks. Mine was humming a lot before it quit. Also had to weld around the return tube because the tank did not hold pressure. Don't forget the fuel filter too. Don't test drive the fuel pump dry, it will ruin it quickly. I found out the hard way.
Changed the head gasket last summer. Took some time. The bolts under the intake/exhaust manifold are quite hard to access. Had to use the right wrench to manage it. It can be tricky to get the valve cover gasket tight.

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