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Crank & Cam sensor which does what?

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Old Apr 17, 2006 | 02:33 AM
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Default Crank & Cam sensor which does what?

My car has been sitting for over 2 months to the last time I started it up, which worked fine just prior to sending it to the bodyshop.
With a new battery fitted today it would just crank, .... crank but not start.
So I checked the fuel pump was priming : could hear it whizzing with ign turned on.
I checked for spark by removing 1 coilpack from cylinder head & spare plug fitted resting against a earth point. spark visible yes.
I did not check if fuel was reaching the fuel rails. Tbh the rubber hose was stuck on tight & would not budge.

I can only imagine its 3 things, no spark, no fuel or its flooded.
So which sensors does what?
Does the crank sensor send the signal for spark or fuel
Or does the cam sensor, which does what?

And if it has been flooded with fuel what to do next?
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Old Apr 17, 2006 | 03:53 AM
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if you take a plug out you should see a puff of petrol vapour. Stub that *** out and you may even keep your eyebrows.

Spark + fuel = some sort of pop bang attempt to start.
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Old Apr 17, 2006 | 01:38 PM
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From search, sensors usually fail to start the car when engine is warm, no info on cold start.

bttt
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Old Apr 17, 2006 | 04:04 PM
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Crank sensor tells the ECU when to fire, cam sensor tells it which cylinders are on the ignition stroke. If either isn't working then the car won't start.

If it's flooded then just leave it 1/2 hour and try again.

Was anything unplugged when it went to the bodyshop? Always worth checking.
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Old Apr 18, 2006 | 05:05 PM
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Tried a working crank sensor & cam sensor today on the car but still not starting.????
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Old Apr 18, 2006 | 09:17 PM
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If its been flooded it could take up to 3 days to dry out enough to start, remove all the plugs, if wet then thats the problem, with plugs out remove crank sensor connector and crank to blow the fuel out of the cylinders (several 10 second bursts needed). Then clean and dry the plugs, refir, reconnect crank connector and try again but do not touch the throttle else you will flood it again.

bob
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Old Apr 18, 2006 | 10:48 PM
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Thanks for taking the time out to reply Bob, was getting worried after the sensor swap as to why it would not start.
I suppose I may as well carry out a compression check if all the plugs are coming out just in case if it still fails to start.
Hopefully it's just down to it being flooded.
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Old Apr 18, 2006 | 11:04 PM
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Personally I'd leave the plugs in, clamp off the fuel pressure hose, floor the throttle and crank the engine, after a couple of ten sec bursts, unclamp the fuel hose.. away she goes (if it was that)

To check if you have fuel pressure, grab hold of pressure hose just before the fuel filter and squeeze, you wont be able to squeeze a lot but it will be enough.
then get someone to turn on the IGN, you should be able to both feel the rush of fuel through the pipe and also the pipe "fill out" under pressure.


Andy
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Old Apr 18, 2006 | 11:42 PM
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I have had the car back from the bodyshop for some time now (at least a month) without me even trying to start it. Intially the original battery was weak & needed a booster to start the engine. So by the time the bodyshop had finished I thought it was long dead, the assistant did say he had trouble starting it up. The car was recovered home & during that time & now Ive been putting it all back together (lights, interior etc) It's only just this weekend that I went out & got the new battery to try to start it.
So if it had been flooded by the assistant in the bodyshop, it would have surely cleared up by now.
Even so I think I still try Bobs method.

Andy thanks for the fuel pressure tip, never thought of that.

Its more annoying when for the last 5 months you have been building it up for a bare shell.

Thanks Ticky
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Old Apr 19, 2006 | 12:03 AM
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Its more annoying when for the last 5 months you have been building it up from a bare shell.

Oh that's truer than you realise...


If it's had a lot of stop start, in and out of the body shop then it's more likely to be coked up rather than flooded, in which case you'll need to take the plugs out after all and give them a seeing to.

Andy
Andy
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Old Apr 22, 2006 | 05:50 PM
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Thanks for all the help guys managed to get it running today, had to adjust the iscv to keep it from stalling though.
Just need the brakes bleeding correctly as the pedal is a little spongy.

Mot & tax next.
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