Hey guys...Idk if this is the right place to post this but ive been having a problem with my '94 xj6.....a few days ago i was driving and the fuel pump had started making a humming noise...when it primes up, it makes the noise and when its on it as well makes the noise....me and my buddy have been trying to diagnose the problem with new pumps, new canisters and fuel filter and none seem to work....the car runs perfectly fine as well...doesnt run bad at all....So, idk if anyone has heard of any bad electrical issues regarding this problem but we strongly think that there is a bad ground connection to the fuel pump....we tested the connections and with the battery disconnected there is still continuity on the ground cable from the cable to chassis....as well, the battery started leaking acid and we were also thinking it could have been the battery since it was in bad shape...so we bought a new one, had the car on for a long time and nothing at all...noise was gone and we had it on several different times today and it seemed fine until i went to the store and there came the noise again.....this is why we figure it might be something grounding out somewhere but could be wrong....any sort of help and suggestions about what to check and such is GREATLY appreciated....next thing to try next is the fuel regulator and check the alternator to see if its going bad.....thank you folks!

 

ide be willing to bet the regulator on your alternator is stuffed and its over charging the battery, ie more then the 14.4 or so volts that should be fed into it when the engine is running. if the battery has leaked acid this can be due to overcharging and likewise the fuel pump will hum louder if its is fed too many volts. but this isnt the correct area for your post, you want the xj40 area. the xj6 that this forum covers was from the sixties to mid eighties (series 1,2 and 3 cars).

if you have a multimeter check the voltage at the battery. overcharging can also be caused by bad connections at the battery, alternator and possibly charge light circuit (could also be the wrong wattage of globe). i dont know if the xj40 has a batterey level indicator on the dash but would have thought with all its electronics it would have an error code up on the screen?


otherwise, a bad ground will cause the fuel pumps to run slower whitch could make then hum under load i suppose but ide be willing to be if the battrey has leaked acid it was overcharging.

anyway, i may be barking up the wrong tree but ide check it out as too many volts can cause serious damage to the sensitive electronics in a car.

Regards,
Jay

 

Hello fellow Jagheads,.. I am having a similar problem with "my #4 Jag" I purchased last Summer, it is a 1984 Jaguar XJ-12 Vanden Plas, it came with the radiator & fan shroud in trunk which was buggered so I just installed another from "my #3 Jag" (a 88 XJ-S parts car) when I finally got it all together I was hoping it was gonna just start up (Ya,ya I know "Wishful Thinking" I mentioned this was my 4th Jag V-12 LoL,. I had e- fuel pump "fun" with my 1st Jag, a 80 XJ-12) but anyways I decided to check the Electric Fuel Pump and it makes a click noise but not pumping fuel !!?? I got out my Test Light and it shows that there is power going to pump in trunk !! Thinking that perhaps the loading & unloading may have done something I also checked the Inertia Fuel Cut Out Switch & it was not tripped !! Any ideas or help would be greatly appreciated !! Thanks