Hi

So this morning my 86xjsv12 started up just fine. Then I go back a few hours later and the darn thing wouldn't start! Tried the basics...any tricks or tidbits? Common faults circulating around this issue?

Much appreciated.

 

Is it turning over on the starter?
If it is turning over is it firing at all?

 

Yah it's turning over..,battery has lots of juice, was running then died...won't start back up..li can hear the fuel pump run for its 3 seconds and then stop...but I suspect some stationary gas just rotted the fuel pump out..

But maybe it's not the fuel pump? Any comments would be appreciated.


If it is though, should I attempt to fix this or just buy a new one? How much do these pumps go for? And should I replace with a jaguar one or is a new one not made by jag okay?

But for all I know it's not the pump..lwhat should I check first before busting out another 200...

Thanks in advance

 

Check the easy stuff 1st. Start with spark, then fuel.

 

wire the fuel pump up to the battery and see if its constantly runs or shuts off again like before. Mine suddenly died on me one day..

 

I agree, check the small stuff. Spark is kinda important.

 

If it was running fine and then just up and quit then that would point towards ignition failure to me. If it was running fine and then sputtered and coughed before quitting, that points towards fuel. If it points towards ignition I would start at the spark plug. If no spark, move back to the cap and rotor. Still no spark? Move to coils. Still no spark? Check ignition modules/wiring. Just keep drilling it down in a logical order with the easiest things 1st.

Good luck!

 

dont forget to try the inertia cut out switch in the footwell , if this is activated or faulty etc, then this would prevent ignition

just a thought

BB

 

Just a question...did you do anything under the bonnet between when it started and when it didn't?

One time I fiddled around a bit and managed to unseat the water temp sensor (front left of engine, two wires coming out of it, mounted to the left front thermostat housing)...it won't start if the plug is not firmly seated in the sensor.

John
1987 XJ-S V12, 62,000 miles

 

I thought about the inertia switch but that only shuts off power to the fuel pump and he said he can hear the pump cycle when he turns the key. I think this narrows it down to either the ignition or the injector pulse.
Ignition is the more probable cause and quite easy to check.

 

Hi

thanks everyone for their resposes.

so if the pump is running, its most likely not the problem...I bought a new filter today...

I also bought a noid tester to check the injecors,

I could also rig up a 100 psi pressure gauge to test the pressure in the fuel line downstream from the fuel pump at the rail end ---- should have 38 psi i think?

Or to test spark i could detach one spark plug lead, hook to a new plug to determine if i have sufficient spark?

Also planning on dismantling the fuel reservoir to see if the pickup screens are plugged with dirty fuel.


All sound good? my bet right now is its a clogged screen or filter. simple stuff first!

But again, if the pump is running for its 3 seconds, its not the pump then?

 

It isn't likely the pump if it cycles the 3 seconds. It also isn't likely that all 12 injectors would plug at the same time. You can loosen the fuel line under the hood to see if fuel is making it to the engine, but I would seriously check spark first.

You don't have to pull a plug, just pull one of the wires and stick a screwdriver in it, then position it near (not touching) something grounded and crank the motor a few times. A good spark will jump 1/4 inch. DO NOT hold onto screwdriver while doing this, you will be shocked at the outcome!
If you don't have spark there, then pull the wire offmiddle of distributor (coil wire) and do the same thing.