I just went through replacing the head gaskets on my 1999 XJR. I live over 200 miles from the nearest Jag dealer, and when I talked to them about the problem, they wanted about $4000 to fix the car (not including shipping the car to them), so I decided to do it myself. I just finished the job, including changing the timing chain tensioners, rails and chains. Pretty involved, but I finally got it all back together. However, now the car won't start. Before trying to start it, I removed the fuel pump relays, left out the spart plugs, and pulled the engine through several revolutions by hand to insure that nothing was going to bind up. Next, I spun the engine using the starter for about 2-3 minutes to insure that the timing chain tensioners were pumped up. Everything seemed fine to this point. Finally, I installed the plugs, replaced the fuel pump relays and attempted to start the car. Nothing. I went back and rechecked all the connections to insure everything was plugged in and tried again. Nothing. I then checked the schrader valve on the driver side fuel rail and found no fuel at all. I then checked all the fuses and the ineria switch, and tried switching the fuel pump relays with other relays that I know are good, and again, nothing. I pulled a spark plug and it is completely dry. Also, I can't hear the pump(s) working at all, so I'm pretty well convinced that I'm not getting any fuel. I don't want to take on the considerable hassle of taking out the fuel tank to check the pumps if I don't have to. Also, I don't have a scanner, but the only message I get is "check engine". Does anyone have ANY ideas?

 

Got your PM:

I read this post originally, and didn't bother to offer suggestions since you sounded like you didn't need them. If the pump isn't running, neither is the engine. Only one pump runs on an XJR dual pump setup at idle. There has been fuel pump info galore the last few days, if you search on my screen name you'll find recent posts with diagnostic tips, and links to more information discussed previously and in more detail in dialogue with XJate, Brutal (where are you, my brother?), and other fine contributors.

You have to buy yourself a scanner to read and clear at least generic codes, and $50 will probably get you a cheap Actron which will suit your needs. Open circuit fuel pumps or link leads do not flag a code though...all the info is archived, check it out.

One issue not discussed from my memory might be of benefit in your case: if the primary pump was getting power but had failed, you might be able to swap the power feeds to the pumps at the connection atop the fuel tank to start the engine using the secondary pump. Not something I have tried, nor would I without looking at the schematic...but a viable idea. If anyone has tried this or knows why it wouldn't work, please chime in.

There isn't anything I can think of that would relate to the cylinder head work (harness connections) which would disable the fuel pump circuit. Go to the source, and examine this as an unrelated issue.

 

Andy, I've jumped them like you described once IIRC. and it started up and ran enough for me to get in the shop. I just switched the pins around.

tcb---- This would confirm diagnosis, but swapping pins should be done as a diag. aid and put back asap once fault is confirmed. I'd try to find a wiring diagram before doing this, too. Even the saltiest of salts like me can't remember the wire colors or pin orientation..... unless I check my diagram and post back. And that may cost ya..

 

Yeah Po, I didn't mean going inside the tank...I'd go to the connector above it as well, or I'm guessing (without a schematic) that you could just pull the pump relays and whip out some jumper wires... direct feed the secondary pump and start the car if you hear it running. Thanks for confirming it will work, that's one of those tricks that gets you home one day without having to call for a flatbed.

 

Thanks to all of you for the input. I am just trying to figure out why the pumps aren't working (both of them worked when I tore the car down to replace the gaskets) and maybe avoid having to take out the fuel tank (I had to do this on my wife's XJ8 and it was definitely not fun). Based on your input, I would like to try and "jump" the pumps to see if I get anything, but I don't know which of the relay terminals to "jump". Any further info on this?

 

You don't have a wiring diagram?

Here's a crude map of a relay:


Ign. feed

Batt. voltage Feed to pump

Ground

So you would pull out the relay for the secondary pump and use a jumper wire to apply battery voltage to the feed to the pump, and the pump will run continuously. You also wouldn't do it unless you were sure which relay you were jumping, and which terminals are which. That's on a schematic, if you're going to poke around otherwise you are doing so at your risk and against my advice. I'd know what color the wires are firsta nd which relay socket was the correct one to validate the test.

Edit: Oh well, the text as it appears made a mess of the map I made.

 

OK, I checked the relays first and they work fine. Next, I jumped the relay sockets and no cigar. Next, referring to the wiring diagram I have, I traced the wires from the pump wiring socket in the top of the tank back to the relay end, as follows: Blue/Red for one pump and Blue/Brown for the other (plus two Black, one for each pump, I assume). I then went to the relay end, unplugged the wiring harness and jumped each wire separately direct to the battery. Again, no cigar. I then did a continuity test of each wire to make sure they are OK, and they were fine. All this done, I guess that both pumps are bad. It is beyond me how this could happen, as the car ran perfect until I tore it down to fix the blown head gasket and replace the timing chain tensioners. Could they go out just sitting there for several months (took me a while to get around to fixing it)?