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Mondeo v6 intermittent starting

915 views 10 replies 4 participants last post by  Macmondy3L 
#1 ·
Hello to all readers,
I have a v reg 2.5l v6 Mondeo.
Started fine this morning but when in car park wouldn't restart. Thought it might have over fuelled ( does so very occasionally ) so tried starting it at full throttle pedal, nothing. Not even a hint of it catching. Called rac and sods law when he arrives it starts first time (look like a prize idiot) and restarts several times. Rac man looks for anything obvious ( no fault codes etc.) but can't find anything

Drive it home, wait ten minutes, tried to start it and again, no start. Turns over quickly but not even a tickle of it catching.
15 minutes later try one more time and starts first turn of crankshaft.

It's not damp and runs without any issues whatsoever normally.

Sort of wishing it didn't start at all until something was found and fixed as now don't know when it's going to happen again

Only thing I can think of of bad connection on coil pack multiplug. Had a look , seemed ok.

Any ideas of anything that can cause such a dramatic start/ non start .
Thanks in advance for any ideas / replies
 
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#2 ·
Firstly, I would locate the three multiplugs for the engine looms located at the driver's side of the rear cylinder head cover. Unplug each one, clean it up inside with a cotton bud or something and maybe spray some ACF-50 or similar inside the plugs.

If no joy, locate the crankshaft position sensor (above the crank pulley on the timing cover, towards the front of the car). Check the plug and wiring all the way back through the loom. If this is all good consider a new crank sensor but they generally either work or don't so more likely a dodgy connection or bad wiring.
 
#5 ·
can you hear the fuel pump priming under the rear seat when you turn the key to position 2?

i had same symptoms in my st24 in that the engine would turn but it would never catch, i had a couple of props - butchered wiring to the fuel pump and also the fuel pump multiplug pins were bend and squint so i hd to sort them out.

proper pain in the arse took me ages to trace what was going on and stranded in all sorts of places.
 
#6 ·
Update
Have followed advice thank you
The car has been starting normally for last few days
Cleaned multiplugs around engine but theydidnt seem that bad
Had a look under rear seat at pump.
I'm afraid I didn't have the presence of mind to listen for the pump priming when it wasn't starting
Saw a very corroded earth connection next to the pump. Cleaned it up and has been starting since but is the fuel pump really earthed thro there. If not what else can it be earthing?
Anyone shed any light as I don't know if I've found and solved the problem or just been lucky for last few days
Thanks again to both previous posters
 
#9 ·
Six months on and update for anyone searching who has similar problems

The earth next to fuel pump does Not affect starting as the symptoms still persist on a once-in-blue-moon basis

Happens about once every 6-8 weeks. Always restarted before rac arrive.
Fuel pump Is priming. Immobiliser is disarming.

Could take it to garage but unless it miraculously does it there for them they will just take my money to tell me they can't diagnose a fault on a working car. I know there are no fault codes
I'm spending the money instead on a new crank and cam sensors.
The old crank sensor spade contacts were quite black which I found odd. Anyway new one fitted and it's currently OK but unless it goes for more than 3-4 months I can't really say if it's worked
BTW the three main engine connector multiplugs are a right pain. Only the smaller one will open. The others are tight shut. I've used copious wd40 but they are starting to break with all the pulling and prodding. If they are not the problem, they soon will be if they break apart much more.
Any advice or tricks as I'm well aware they could be hiding a bad contact. Thanks
 
#10 ·
10 weeks since the crank and cam sensors were replaced and it's been starting perfectly. Looks probable that some thing was up with the contacts on the crank sensor. Guess not many cranksensors get to this age so not too much info on why they went black. Car will probably makeanother year or maybe two
 
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