So my 1996 XJ6 LH american version jag didnt want to start the other day when i parked it by my job. It was running fine up until that point. So i checked the relays and switched them around and nothing. I left the car where it was and took the train home. I returned the next day and tried starting it again to no avail. I switched the relays and nothing, by this time my battery was practically dead so i put my girlfriends battery in the car and tried starting it, nothing. I kept trying and out of no where it started up! I drove it home and tried starting it again and nothing. I would check to see if i heard the fuel pump when turning the key and it wasnt turning on. So i bought a new relay, replaced every single relay with the new one and tried starting the car and nothing. I checked all the fuses through out the car, all good. I tried jumping the fuel pump with the 30\87 terminals and nothing. So i took the fuel pump out thinking that since i have 107000 miles it was about time it gave up on me. I connected the fuel pump when it was out of the tank directly to the battery and it turned on, so now im perplexed. What could it be? I have a new pump coming in that i am going to install anyway, but what could it be?

 

Does the tach read 200-300 rpm while it is cranking but not starting? I THIUNK most times the fuel pump just quits and does not come back, but good luck!

 

Agreed.

That small rev reading whilst cranking is a sure test as such of teh crank angle sensor, no reading is a dud CAS.

Look VERY carefully at the plug associated with the CAS, on the front RH side of the timing cover, you will notice it is vertical, and the top is open to the elements. Mine did the hissy bit after a rain storm, and moisture had found its way in there, and mixed with the oily mist already in there, and no go was the result, then misfiring, then clear as needed. I sealed that thing with RTV, after a good clean out, and a recent drowning of the front of the engine had no effect of running.

While the tank is out for pump renew, check very carefully the wiring going thru the top of the tank leading to the pump.

Also check the small wiring loom traversing the RH trunk hinge. many, many no go, etc on the X300, has been traced to broken wire/s in that sucker.

 

That one's news to me! I suspect I have issues there (dodgy boot release button), but hadn't realised it was likely to cause any more serious problems. That task has been moved up the list!

 

Good tips guys! I will check all of those today! Is there any way I can test the pump with the original connection out of the tank without blowing myself up? Also the CAS should be good since I get a 200-300 rpm reading while trying to start it. I am still getting the new pump since it only cost me 17.50 on ebay. I just am concerned since when I tested the pump out of the tank directly to the battery it turned on. Any suggestions>?

 

OK, here goes from downunder.

Grant's rule #1:

ALL Jaguars are female, think about it. So logic is not on the radar.

My sons BMW 740 did just that, bench test, sweet, in the tank, zip. Took me a few snorts of JD to work out that in the car the pump is vertical, on the bench we had it horizontal, I KNOW, should not matter, but it did, worn out pump obviously, but held vertical out of the tank, NO go. BMW $670, Mitsubishi pump $59, hose clamp $2, all done.

With that lid off the tank I would use a DCM (digital volt meter) to test the wiring at all points you can access. You really dont want a spark from a pump connector upsetting your day.

 

Thanks Grant! I will test the connections to make sure no spark occurs. I will let you guys know what happens!

 

So I installed the new fuel pump and buttoned everything up and still no start. I don't even hear the pump turn on. Last time I heard the pump turn on the car started right up so it's definitely something to do with the pump, but after installing a new working pump still
Nothing. Any ideas?

 

Bugga.

I am assuming you have voltage to the required wire to the pump via that top connector?.

Also assuming that the relay is actually earthing the system. The relay may "click" but is it actually doing anything.

I am not aware of the X300 having these issues, BUT, on the mighty XKJ-S the wires in the relay socket had a bad habit of pushing out of the socket as the relay was pushed in, and the fuel pump relay was the main culprit, and coz that wire did not drop down totally was not easy to find.

X300 do suffer from earth issues now that old age is creeping in. I would check the earth side of that circuit as well as the power side.

A hot wire to the related terminal in the top connector and an earth wire will deem the pump good or bad, as it will by-pass the management system totally.

CAREFUL DOING THAT FOR THE OBVIOUS REASONS.

If the pump fires up, it is in the circuits before that connector, if its dead, then deeper investigation once more will be needed.

JUST HAD A THOUGHT, COLD COFFEE AND ALL.

Has the inertia switch had a hissy. I have read about that sucker on here many times as causing all sorts of running grief, and causing the owners to become serious drinkers??.

 

Grant thanks for the info! I removed the connector for the fuel pump and put to wires directly to the connector and the fuel pump turned on. So I figured this might be a way to temporarily fix the car since when I tried starting it after the pump was on for a second, the car turned right on then turned off when the fuel the pump sent to the engine finished. SO I thought, why not splice into the existing wires that the connector has from the main harness and jimmy rig a switch. When I tried doing that and connecting the wires to the battery the negative terminal would spark, even though nothing was connected yet! I don't know if that helps but I need help!

 

you should check continuity/resistance from the relay to the pump. make sure there's no short. if there is then the easy way would be to rewire it urself from relay to pump. the hard way would be to trace the factory wiring to the short. on the relay verify that when cranking the engine you have 12v between the pink/brown and the white/pink wires. thats the signal from the ECM to activate the relay. if there is power there and you are sure the relay is functional then the RED/YELLOW wire is the positive to the fuel pump, and would be the one causing the problem on the relay side. NOTE the BROWN/YELLOW wire is always battery powered. also check the negative wire on the pump could be a loose negative connection to the car. here is the relay , pump and ground info. good luck!

 

I WOULD NOT jimmy that circuit, TOO BLOODY dangerous, MY opinion of course.

If something went hisyy, the insurance mobs would have a field day.

I know its a PITA, but please sort it properly. It sounds like a relay,or wiring issue to me. If there is no V in the required wire at the connector, work backwards until the break, or whatever is found.

 

Just had a thought, I know scary as hell.

Try resetting the inertia switch. It cuts the fuel pump circuit for safety reasons. I have read of many posts on here and that switch has caused many a no go, and a simple OFF/ON and life returns.

 

Thanks for all the info avion and grant! I will check the wiring and voltage. One question about the inertia switch. I know where it is, and have located it and thought I checked it correctly. Would you be able to give me the step by step process on how to reset it? and furthermore, do you think it needs resetting even if the car started when I wired the fuel pump directly? Or is the fuel pump the only thing the inertia switch cuts off? Thanks guys!

 

when the inertia switch pops like it should, the car wont crank, it cuts power for safety reasons. it resets simply by pressing it back in. its a push button mechanism.

 

The reason it starts with the by-pass wiring, is due to that by-pass eliminating the control circuits in the car for the fuel pump, whether that be inertia switch, relay/s, ECU, etc. Basically the fuel pump is/was "hot wired".

My understanding of the inertia switch (and I may wrong), in our market, is to cut the fuel pump circuit in the event of a collision, and/or roll over.

All my Jags fitted with them still crank just fine, but failed to fire, as the fuel pump is dead.

I know not where it is on the LHD cars, ours is just inward of the bonnet release handle on the RH side.

 

I found the inertia switch, it is under the glove box on the passenger side of the vehicle with a removable rubber cover. (LHD vehicle) There is a button inside of it that I can press in and it bounces back up. Is there something im not doing, or a procedure ?

 

Nope.

Sounds like a dud switch.

Soooo, just for giggles, join the wires together, anyway you can, and see what happens.

Dont leave it like that for safety reasons, but if it starts and runs, at least the hunt is over.

 

not sure if this helps, but the x300 is alot like the xj40, albeit improved in a few areas.
if the 300 is the same, if the crank sensor fails, you get no fuel pump, no spark etc, so if you`ve replaced the fuel pump and can`t hear it priming with ignition on etc, it may well be the crank sensor!
the symptoms you describe certainly sound like it is. one minute they work fine, next they don`t or are intermittent.
for what its worth and how long it takes, try removing it and giving it a good clean. sometimes, but not always, a clean is all they need. the engine is prone to catch alot of muck up the front end and you may well find its covered in gunk!
worth a try.

 

Ok so I finally got the car started! I was working on it over the weekend and jumped the relay to the fuel pump and the pump turned on so I knew the wiring wasn't broken anywhere and that the contacts where the relay goes in were good. SO I started switching relays around and nothing. Eventually my battery died so I took my friends brand new battery from his car and put it in mine since my jumper cables suck. I attempted to start it and boom! It started right up! I took his battery off with the car still on and put the terminals back on my battery and drove to the nearest autozone for a battery check. turns out my 8 year old interstate battery was no good, despite still holding a charge. After buying a new battery, the car has started every time now. Very weird. So im happy to say that the problem seems to be fixed! Anyone have a similar issue?