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Cosworth issues?

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Old 06-03-2012 | 09:31 PM
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Unhappy Cosworth issues?

You can be driving along at any speed then all of a sudden the engine cuts out, I try to bump it back into life whilst moving but it doesn't work. Occasionally it will come back to life whilst bumping it on the move, sometimes it dies, spluters once then starts itself a bit like a misfire but not sure? Everytime it cuts out though its smooth so that your not aware its gone until you have no power. Plus it wont restart again until the ignition has been turned completely off.

One thing i have found strange is that the turbo still seems to spool, like i'm hearing the noise but no power? I've probably missed loads but any ideas before i start buying things i don't need? Oh the car is a 1991 H Sapphire 4x4. Thanks.
Old 06-03-2012 | 11:38 PM
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Check the relays under the dash, I had a similar issue a few years ago and was the connection plug on my fuel pump relay, and by turning the ignition off and back on it temporally connected again, took me ages to find out what it was, but after close inspection the relay terminal block was a little melted.
Old 07-03-2012 | 12:31 AM
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Does the rev counter drop when it happens?

TBH from your description I would expect it to be an earth or a relay.
Possibly fuel pump if its that smooth as it dissapears.
Old 07-03-2012 | 06:56 AM
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Originally Posted by Chip
Does the rev counter drop when it happens?

TBH from your description I would expect it to be an earth or a relay.
Possibly fuel pump if its that smooth as it dissapears.
Yes the rev counter does drop, sometimes its the only way i know its gone haha, its funny you should mention earth, because a few weeks ago if you were giving it a bit gas the rev counter would go wild and the car would misfire, but we found the dodgy earth ( the one on the bonnet ) and sorted it and that seemed to stop the flicky rev counter and the misfire.

Do you think it could be wiring to the fuel pump maybe? Just cos its only 11 months old and was rewired by Karl at NMS, I know they can go at any age really though.
Old 07-03-2012 | 06:58 AM
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Originally Posted by daz1968
Check the relays under the dash, I had a similar issue a few years ago and was the connection plug on my fuel pump relay, and by turning the ignition off and back on it temporally connected again, took me ages to find out what it was, but after close inspection the relay terminal block was a little melted.
Daz i'll check those relays too, its had a new pump relay so i'll check them all, we were thinking maybe coil etc put i'm sure that wouldn't just cause it to cut out but also miss a lot
Old 07-03-2012 | 07:06 AM
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Also check the fuel cut off switch in the spare wheel well. Had problems with mine so removed it and replaced with a suitable piece of wire.
Old 07-03-2012 | 07:29 AM
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Originally Posted by timotei1980
Also check the fuel cut off switch in the spare wheel well. Had problems with mine so removed it and replaced with a suitable piece of wire.
It doesn't have one lol, maybe it was removed when the fuel pump was rewired?
Old 07-03-2012 | 07:41 AM
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I had this, the crank sensor plug on the loom was a bit broken. Put a new plug on and problem solved
Old 07-03-2012 | 11:04 AM
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If the rev counter is dropping its not the fuel pump.

Working backwards from the counter:

rev counter gets fed by
ecu output which is based on
the ecu seeing a crank sensor signal
which is based on the crank sensor working and the earths/positives being in good condition


So i would say either crank sensor fault, or earth probably.


Crank sensor faults are relatively common, and its good practice to change it every few years, so I would start with that on the basis it will do no harm to have a new one if the old one is all old and wire gone rigid etc now anyway. Buy from a trusted supplier to get a genuine one not a copy, MSD or Reyland or Burton etc for example
Old 07-03-2012 | 05:23 PM
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Id say earth or crank.

As said crank sensor is a common problem. It would be good practise to redo all your earths anyway as they will be dirty and rusty so will give you a poor connection so worth doing!
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