89 XJS V12-- Engine died after I drove out of my driveway. Will not start now; has gas, engine turns over, not even tries to start. Fuel cutoff switch is down.....don't even know where to start looking. Any ideas???
Dick C.

 

Do you have Lucas or Marelli ignition?

Mark

 

Marelli. Lots of Lucas stuff in the car though.

 

Ok, then start with the basics;

1. Do you hear the fuel pump run (for a second or two) when you turn on the ignition key?

2. Do you hear the injectors click one time when the key is turned on?

3. If you have fuel at the injectors then check the ignition.
Do you have spark out of the coil? If yes, do you have spark at the plugs? If no spark at the plugs then check the cap and rotor.
If cap and rotor OK then check the Power Resistor Pack located on front right side of the engine bay next to the radiator. Make sure the connector is clean and making good contact.

4. If you have fuel and spark check the front crankshaft position sensor. You should find the connector on top of the engine near the AC compressor. Unplug the connector and test the impedance of the sensor. If it is under 4 ohms then it is no good. Replace it.

5. Check the Coolant Temperature Sensor. It should have resistance. If it is "open" then the engine will not run. Replace the sensor.

Let us know what you found after making these checks/test.

Mark

 

Thanks Mark, will start on these right away!


Dick

 

Also check the crank sensor in the front of the engine and the flywheel sensor at the rear of the engine. Either one will prevent it from starting. Using an ohm meter, they should read about 700.

 

just had the water pump replaced, could they have messed up the front sensor? I'v tried most of the things that Mark suggested and still no start, it will do a 'whuff' when first cranking the engine, will do it again after a couple hours.

 

The sensor is mounted under the crank balancer. Its pretty easy to reach from under the car.
The cable snakes its way up to the top of the engine and plugs into the engine harness. Find that connector and separate it. Measure the resistance of the sensor. A good one will measure .700 ohms. If it is much lower than that then the engine will not run.

Mark

 

Sorry I've been out of touch, was out of state last couple months.
Mark, I've got a different 'traveling mechanic' working on the car now, gave him your list and he has gone over all the tips, finally he finds the temp sensor 'open'? Found a new one, $40 bucks, so will get that and hope it works. Will update soon.
DickC.

 

You can test that by simply unplugging the cable from the sensor and putting a resistor across the cable ends.

If the ambient air temperature is in the 70 - 80 degree range, a 2k ohm resistor will be about right. The temperature actually should be the coolant temp, but if the car has sat for several hours then this should be close enough. If it starts with the resistor across the terminals then it points to a bad sensor (or a sensor that is simply unplugged or has a break in one of its wires).

Good luck!

John
1987 XJ-S V12

 

Okay to all who helped me....Good News!! It was the front crankshaft sensor, bought a new one from Jag for about $60, my mechanic put it in and it started right up!! Old was covered with grime but cleaning it did no good, it was totally open.
Nice to have my ride back.
Thanks to all of you for the help!!
DickC

 

That same sensor gave me all kinds of trouble when I was trying to get my car going again! In my case it was the wiring, I had connected the coax wire to the plug wrong. I swapped the ground and signal wires and the car fired right up. The next time the thing won't start, that's the first thing that I'm going to check.

Glad you got it running!

 

I have to admit I'm a little gun-shy now, every time I shut it off now I hold my breath when I start it back up....guess I'll get over that eventually but haven't got to far from home yet!!