2003 XK8 stalled on freeway onramp, just cut out and will not start. Not throwing any codes, engine spins fine. I put a pressure gauge on the fuel rail and got zero pressure when turning ignition on. I got the wiring diagram and tested the output of the fuel pump module that goes directly to the pump and get no voltage there.

I want to make sure I'm testing this correctly - when can I expect the fuel pump to be on?

Thanks, Steve
2003 XK8 coupe

 

Hi,
With the ignition on (position ii) you should have 12V on pin 5 of the fuel pump module via F5 (30A) in the trunk fuse box.

Does that check out OK?


Mike

 

Perhaps a check of the Inertial Switch behind the left kick panel as detailed in owner Manuel would help. If tripped, it would not allow current to fuel pump. It is located at top of the panel on left side under the dash forward of the door opening.

 

Thanks, I'll check these things tonight.

 

Fuel pressure is available over OBDII as well. There is a fuel pressure sensor at the end of the rail, as this is a return-less system.

With the diagram, locate fuses and relays and double check them. I believe the pump is expensive, with no cheap alternative that I know of. If it boils down to replacing it, I believe the Coupe is easier than the Convertible.

Best of luck, keep us posted.

 

I checked pin 5 on the fuel control module, and there is 12V+.
I can't find the inertia switch, but expect that I'd be having other troubles if that were tripped.
I'm going to get help this weekend and see if the pump gets power when the ignition first goes on. Other than that I have no other ideas.


Thanks!

 

Not sure you'd get any codes with tripped inertia switch...

 

Fuel pressure is available over OBDII ? That's good to know. It's a lot easier to monitor readings while driving without having to tape a fuel pressure gauge to the windshield !

 

To be clear, only the the 4.2 L cars, not the 4.0s.

 

Can anyone tell me where the inertia switch is on a 2003 XK8 coupe? It is not in either of the triangular shaped panels on either side of the dash. I looked in the passenger footwell but didn't see it.

 

It is supposedly behind the trim, on the left of your left foot, by the foot rest. So, same general area as the previous car, but hidden behind the plastic trim. I have never tried to locate it myself...

If you search the forum for this inertia switch, you will find a recent posts. From memory, a bunch of stuff is turned off when that switch trips, not just the fuel pump. I suppose the electrical diagram would tell you the exact details. In short, if only the pump is off, chances are the inertia switch is fine...

 

Thanks fmertz, I'll dig into it tonight.

 

FYI- I replaced the fuel pump in my 2000 Coupe 3 years ago, part was about $60.

I was able to do mine without removing the tank, working from the trunk (er, I mean boot) and through the subwoofer hole.

 

Hi
You should hear the pump cycle as soon as the key is turned to the start position, if not suggests either no input voltage or dead pump, my 01 pump died about 18 months ago
My Indi mechanic suggested that I remove the cover in the boot and tap the tank several times with a rubber mallet!!! It worked and pump came back to life , unfortunately it only worked for a couple of days . Replaced pump, all ok, seems the pump is the most usual culprit in this scenario.
Jeremy

 

Check ignition switch is doing what it should and PATS also since when it stalled I think you ought to have got a P1582 - except where the car thinks you "asked" it to switch off (e.g. by turning the key off or some electrics simulating that).

That said, the lack of fuel pressure is a big deal.

 

I found the inertia switch, right where fmertz said it would be. You can reach it and press the switch over the top of the panel to the side of the foot rest. I pressed it in, but it didn't help.


I did tap into the power wires going to the pump, and they do get power for a second or two when you hit the ignition switch. I'll try some more testing tomorrow.


I didn't get any codes from my ODBII scanner (just the P1111 indicating all is well).

 

Hi
still sounds like pump its normal to see power of fuse 7 for a couple of seconds as the pump is energized, suggest you access the connector coming from the relay to the pump if you remove the cover over the tank you should see a second connector on top of the tank that goes directly to the pump I believe its pin 6 that brings up the 12v to the pump , if you disconnect it there and read from the pump side connector pin 6 to ground you should see a closed circuit on a meter if not there is no circuit thru the commutator on the pump and pump is dead

 

Couldn't get the connector on the top of the tank, but there is an intermediate connector mounted on the tank and going to the top of the tank. I tapped into the two wires (red and yellow red) that go to the pump. With the plug disconnected, I get no continuity from either wire to ground. I DO get zero ohms across the two.

Can't hear the pump come on when I turn on the ignition, then again I've never heard the pump.

I'd like to make sure that the pump is bad before I spend $500 on a new pump and a weekend tearing into it. The pump changed on the 2003+.

Thanks all.

 

I finally got around to listening for the fuel pump and I can hear it whir for a second when the ignition is turned on. Does this mean it should be OK and I need to focus elsewhere? Or can a pump fail and still make sound?

 

Is the measured pressure within spec? (Probably not.)