Jaguar XK8 cranking but no start 1997
 

After driving for a while i parked the car for half an hour’afterwards it sudenly didn,t want to start anymore it cranks
but doesn,t want to start .
it has a fully charged new battery and the engine always started perfect until now.
i measured the fuel relay and checked all fuses all are fine and tested,but it seems the fuel pump doesn,t get its ground to activate the fuel relay,the pump runs if you by pass the relay.
where does this ground cme from?
it seems to be the ECU?
van anyone help?

Does the engine turn over but does not start or does the engine even turn over?
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Rik
 

it cranks fine and has compression but doesn,t run most likely due to a lack of fuel the pump relay is NOT acrivated

One input to the ECM to activate the pump is the CKP. If there is no signal, the ECM shuts down the fuel pump.

Yes, the ECM provides the earth part of the circuit for the fuel pump, and regulates the fuel flow based on engine load.

Welcome to the forums Rik,

I've moved your question from General Tech Help to X100 forum. This is the place to post technical questions about your model.

Please read the guidance for new members ( https://www.jaguarforums.com/forum/n...ned-up-241802/ ) which answers many of the most frequent questions about getting started on the forum.

Enjoy the forums.

Graham

Check the tach while cranking. If it doesn't show around 200 rpm the CKP is likely bad.

Dear Enthousiast ,

Thank you very much for your reply i assume the ckp is the Crankshaft position sensor? Which is located at the back of the flywheel underneath the car?
this gives the signal to the ecu and this translates it to the fuel pump ground signal ,right?
it also gives the ecu the signal for the spark timing ?
Then this must be the fail cause as it suddenly appeared ,the computer seal of the ecu was broken and the inside cappacitors which are prone to leak and fail are looking new as well as the condition from the pcb inside.
So the ckp is most likely the route cause.
i will check this today

Try starting the car with the throttle pedal floored for 5 seconds and then gently lift off your foot off the pedal while still cranking.

If this resolves your issue it means it's just a bore wash problem, well known and documented on these cars. Otherwise you might check your fuel pump, also known for being a weak point.

Dear Ryan I tried your procedure many times with no result I have heard more of this procedure but I think the crankshaft sensor is broken as the computer ecu looks fine on the inside no blown capacitors so I ordered a new sensor
the tach is also not moving when starting

Sorry to hear that, while annoying bore wash when it happens is easily fixable but you seem to have another problem. Keep us posted when you put your new sensor.
Good luck

When you go to start the car, the ECU turns on the fuel pump for only a few seconds, then stops, when the car starts the ECU turns the pump on again. The only way you can check it is with a light connected to the fuel pump wires. I drove a pin through each of the wires then connected my test light to them!

I suspect that the tachometer is driven by a signal from the ECU and that signal probably originates from either the crankshaft position sensor or the camshaft position sensor. If either if these sensors is not functioning then the engine will not start. A code reader should display the relevant fault code.

Richard

Hi Richard ,many thanks for your reply ,i had connected 2 obd readers 1 from Icarsoft lr2 and a carthink but both does not give a sensor code ,but it can be either the crankshaft sensor or the rockershat sensor .
So i gambled to first try the cranshaft position sensor as the tachometer is not showing any revs wen starting.
Hopefully this works,thefuel pump works fine but is not activated by the relais even not a few seconds before starting.
So hopefully i am lucky and the car starts again and will be back on the road .

Many thanks for your help

Help needed crancking but no start
 

After a few weeks my crankshaft position sensor arrived unfortunatelly it didn,t fit as it had a seperate connector ,not a sensor with a wireand wire connector.
So i made 2 connection pins to the excisting cable ,i don,t know if the polarity is important by these sensors but i assume not.
i tried to start after refiting again with no succes.
The tacho comes from the corner just a bit when starting now but its the same as before.
At the moment i am helpless what to do,the local jlr dealer is not intrested in my car and there seems to be no knowledge at all.
so far i tested,
1 Fuel pump ,ok
2 Fuel pump relais.ok
3.Fuel supply filter Ok
44Emergency switch ok
5.Cranckshaftpos sensor ok
6Battery ok new
7Wiring and ground ok


The car always run fine before it sudeenly didn,t start
is it the ECU?,?
Can this be swapped on this early car ecu starting with ANJ.
OR can this be rebuild ?
Any help will be much appreciated

It is unusual for leaking capacitors in a 97 ECU to prevent starting, usually just a misfire on several cylinders. But since it is a 97, it is probably a good idea to open the ECU and look for damage.

Dear member,

i opened the ecu and had a look inside the unit,the pcb just looked as new inside ,but why doesn,t the car start at all so suddenly

Crancking but no start
 

I am struggling for months to get my xk 8 1997 running again after using the bible and going to all possible issues ,the ECU seems to be dead and can not read by the obd scanner.
can you please help me to find a reliable ECU repair company with warranty with good reviews?
in Holland i cannot find a good repair company.
my ECU IS THE LJA1410 CA
TEH CAR HAS VIN NUMBER SAJGX274XVC015871
MFD 06/97
Paint PDX
TRIM SDC

Rik,
I've copied the content of your latest post back here. It's better if you keep everything in one place.

It's possible that the ECM could be in trouble, but you're getting as far as a crank, so it can't be dead.

Can you pull any codes with your reader(s)? There should be something, even if only P1000 / P1111.

Do you have fuel pressure at the Schraeder valve on the motor after you have done this?

Will the car start & run if you bypass this relay?

If not, do you have spark?

Dear Member i cannot pull codes out of the ecu it says connection is ok but cannot read codes due to a problem .
Do not know what to do there is no pump activitu due to the ground from the relay which isn,t connecting the fuel pump.
There is also no spark as it doesn,t want to run with fuel in the inlet .
i replaced the cranckshaft sensor already but It seems that i got the wrong one as this had a connector on the sensor itself

It may be your OBD tool(s) - what have you tried?

Oh ffs - PLEASE DON'T DOUBLE POST!! https://www.jaguarforums.com/forum/x...1997-a-273524/