Fuel pump woes

JimboV8

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Take a plug out and check you have a spark.

How did this problem come about? Was the car stood for a while?

If you do get a spark then it’s quite possible you have “bore wash”.
 

mcw739

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Hi Jim,
The problem started about 18 months ago, I went to move the car out of the garage, it fired then died. Diagnosed as fuel pump because no rail pressure. Behrevements in the family and not enough enthusiasm to drop the rear suspension to get to the tank line connectors stopped me in my tracks. Anyway with fresh vigour I'm trying again. New pump installed and the problem remains. Originally the fuel could be heard flowing back into the tank before starting the engine but now there is nothing. Some people have said the pump should just pressurise the rails and the stop but it never did that, always just ran.
 

x-files

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In summary - despite cranking the car does not attempt to start, no ECM signal to fuel pump, and/or spark and/or injectors. Does not sound like a fuel pump issue to me.
I would be checking for harness issues - a short/break in the fuel pump supply might be just the problem the ECU is picking up. -
As MG mentioned usually if it cranks it's not immobiliser or gear interlock (not much point in letting the car be moved with the starter in either case!)
 

MGinterloper

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Take a plug out and check you have a spark.

If you do get a spark then it’s quite possible you have “bore wash”.

I like that. Back to basics :smile:
And do a compression test to make sure the "bore wash" isn't messing with you.

In most engine management systems you only need three things to get it started (or at least attempt a start)

1, fuel pressure at the injector rail
2, starter motor spinning the engine at a minimum of 500 rpm to generate compression and crank senor pulses (have you checked the crank sensor?)
3, cam sensor to synchronise with the crank sensor to determine when to let the fuel and spark do there stuff (have you checked the cam sensor?)

Currently we don't have the first item without forcing the power on to the pump! Did you check if you could make the pump run via the relay by grounding EM13-1?

I'm starting to think this may be an immobiliser fault after all. Could you do a cable continuity check from EM10-6 to FC22-16 on the key transponder module connections? While you're there check continuity from EM10-17 to FC22-17...
 

mcw739

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Just realised I didn't report back on this. I sent the ecm off and it was found OK. I replaced the fuel pump. On attempting to start the engine it coughed a bit now and then so I persevered and cylinder by cylinder it slowly came back to life. So, feeling extremely foolish I have to report the problem was bore wash all along. I really am surprised, I don't recall running the engine for a short while and switching off but I must have, its so long ago lol. The other 'red herring' was I was sure the fuel pump ran all the time while the ignition was on, it doesn't. It runs to pressurise the rail then stops and waits until it gets a drop in pressure and engine running signal before operating again.
So the car has been pressed into service because my everyday x-type has been pranged, not by me but a hit and run delivery driver. XK passed its mot and is now getting wet in the lovely English summer.
Thanks to one and all who offered advice, I think the thing learnt is 'simple things first'!
 
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