Hi All,

Looking for the location of the CKPS crank position sensor [engine speed sensor]I took on a project XJR with the AJ27 engine, replaced the fuel pumps and filter cleaned the tank, injectors and lines cleaned the supercharger, throttle body replaced gaskets and seals. I have read its on the bed plate?

So now I have fuel pressure 38 - 40 psi at the rail the engine fires up but dies after a second or two with no codes.

Anyone have any thoughts I know the fuel system is good I am thinking a bad sensor or connection.

cheers Paul

 

Attached is an excerpt from JTIS. The sensor is on the bottom of the flywheel cover.

 

Do a search about the XJR fuel pumps. You have 2, I maybe incorrect but I think the secondary charges the fuel rail and the primary runs the engine. The secondary then only kicks in on high rpm fuel demand. The trick is to pull the relay for the primary pump and start the engine a few times and then the secondary will become the primary. If that solves the engine stalling after start then you know your primary pump is bad.

 

Thanks, but as I said I have two new fuel pumps and 38 - 40 psi at the fuel rail I can jump 12v on the pump fuses it makes no difference the fuel system is good.

Looking for what else can stop the engine running

 

So I did some more checking the ignition system work fine the car will run all day on starter fluid, after the initial start my injectors are not firing what triggers the injectors? what determines the rate they fire?
thanks

 

It's probably the PCM deciding something is wrong so doesn't inject fuel. Missing CKP pulse would do it, I expect.

 

Mine's a 99 but similar to yours. I replaced the pumps and removed a jumper wire that someone prior had stuffed into the ground lugs on each of the fuel pump relays. The jumper was then run to ground at the relay box to trunk floor bolt. With the jumper in place the car would start and run fine, without it sounded like yours, crank, start for a second, and quit. I took the jumper out and removed the relays. I used a solder iron to flash a thin coating of solder onto each of the spades protruding out the bottom of the relays, plugged them in, and back in business. I'm not sure if that's what's going on with yours but it's easy to try. If I run into any other electrical issues my first step is going to be to flash the relay terminals....

 

Turned out to be the MAF sensor wiring rubbed through on the belt at some time, repaired the wiring and all is good now.