AJ27 required cranking rpm

X-Type
1

I had to renew my Jag-Lovers subscription and this site is new to me again, since several years ago when I owned much older Jaguars. So, if I am on the wrong blog, please forgive me.

I am seeking the required cranking rpm for the ECU to turn on the fuel pump for an 2000 XK-8 4.0 liter. The fuel pump is not getting a signal, and I suspect a problematic ECU. I don’t have access to this data as I don’t possess an OEM Jaguar firmware tool. The reason I am asking, is that I’ve checked all relays and inertia switch and fuses, and fuse box and wiring continuity, and neutral switch. I don’t want to hot wire the pump yet to check why it’s not turning on when the key is on, and when cranking. I’m usually an electrical guru, but I’m scratching my head. The car has been to 2 shops, and no DTC codes are present. Go figure. You fellas have been good to me in the past!

Thanks, Brandon

2

Brandon, the fuel pumps on the X308 have been known to fail completely that is the inards have broken down completely, will it run if you power it directly? Have a look in the Archives as this topic was raised about 8 years ago, Ross and I had somewhat different takes on this!

Also it may be better answered if you post in the C300 or XK8 Forums. I think you may also have 2 pumps in your car also.

3

Seem to recall >200rpm for a start signal.

In the XK8 you only have the one pump as I’m sure you’re aware. I would definitely jump points 3 & 5 just to prove the pump runs. Also try a different relay of the same type.

Battery voltage sometimes gets forgotten about.