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XJ8 Dosen't Start

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Ferro

Freshman Member
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I have 1999 XJ8

The car was running well. But last week when I started it up the idle was rough.
I turned off the ignition and tried to restart, it wouldn't start.

The engine is cranking at normal speed.
I charged the battery anyway.
Checked for bad fuses and broken or loose wires on the sensors list below, none found.
I checked for Fuel pressure at the fuel rail, I have plenty of fuel pressure.

I checked what I believe is the camshaft sensors located at the front of the engine facing up out of the valve covers.

The Left sensor has a 2 volt output when the engine is cranking the sensor on the right has a 5 volt output. Both have good pluses with the exception of the voltage differance.

I've also located two sensors at the rear of each cylinder head but I haven't checked the out puts yet.

I can't locate a crankshaft sensor, does this car have one?

I would appriciate any recomendations on how to proceed.

Thank you!
 
You do not mention if you have any OBD codes. A no code will probably be fuel. You must use a gauge to know exact fuel pressure. For the crank sensor look from the front of the bellhousing. Opposite side as starter. Follow harness from above. Crank sensor works off the flywheel. Saw the same problem on another car.
 
Hello Larry,

I will check the OBD codes,fuel pressure and crank sensor today.

Do you know what the fuel pressure should be?

Thank you!

Ferro
 
Checked OBD codes, readings below.

P0102 MAF VAF Cirduit low input

P0112 IAT sensor 1 circuit low input

P0335 Crankshaft position sensor A circuit Malfunction

Checked continuity from Crankshaft sensor connector to ECM connector, continuity good.

Checked Crankshaft sensor resistance, reading 1K ohm. I'm assuming that the 1K ohm is a good reading.

Noted no voltage on the Crankshaft and rear Camshaft sensor s with ignation switch in the run position.

Also noted that front camshaft sensors have voltage with ignation switch in the run position.

Did not check fuel pressure.

Any thoughts on what to check next or how to isolate the problem?
 
If a jag is shut down immediately after starting the engine will get severly flooded and the cylinders get washed with gasoline. I would confirm this with a qualified Jag Tech but I believe the plugs will have to be removed and some oil put into the cylanders to regain the compression required to restart.

What year is the Jag?

dave
 
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