None starting ABY

[quattro estate]

Hi all anybody any ideas?
ABY engines runs without any issues and starts from cold without fault. But after 10 miles or more, switch it off for a couple of seconds or even 45mins it won’t start….just tried a little easy start up the air box and it started so I guess it’s fuel related??
I did fit a new cam sensor but I thought that fixed it?

[Crasher]

It could be fuel boiling in the injector rail, the S2 was prone to this in period, have you tried cranking it over for a long period? When it won't start, look at the measuring block in the live data screen to see if the two crank speed sensors are sending a signal, they can fail when hot BUT that usually causes the engine to cut out when hot. I have the fuel boiling issue with the S2 I have been doing and I am carrying out the RS2 fuel pump upgrade we used to do when these were current. This has a reverse flow check valve on the pump output (like K-Jet systems) which keeps the fuel in the lines pressurised, stopping it from boiling and vaporising.

[quattro estate]

Massive thanks for the reply….I'm unsure if the fuel could be boiling as I'm not thrashing it before I switch off and it’s instant as switching it off and then trying to restart with a second or two
i will have to check the crank sensor but as it starts with easy start surely it’s unlike to be electrical?

[GT500]

Definitely cam sensor.
poor some cold water on it when it's failed. When it then restarts that confirms it.guessing the replacement is faulty.

[quattro estate]

Cheers for your input ?. I will try that tomorrow but what a crap job to do again if it works??

[GT500]

Not a great job to do, true. At least the water trick can tell weather it is at fault without just changing it in hope.

[Tractor Dave]

By spraying easy start you are only confirming you have a spark. Fuel pump won't run if cam position sensor isnt getting the correct signal in time with crank sensor. If you changed it recently i would check the wiring first. I made up a led bulb to check cam sensor. Very easy to make one.

[Tractor Dave]

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[quattro estate]

Fantastic picks and thanks for the info??

[quattro estate]

Hi all. I’ve now had time to check the wires and connections to the recently fitted Ultra cam sensor
its got a good earth and both red and Green have 5 volts up to the sensor side of the connector
reluctantly it looks like the sensor unit has failed
anybody else had issues with parts etc. thanks

[Crasher]

I fitted an Ultra Performance G40 to the S2 engine I built and fitted earlier this year and it has been perfect with the POGO pulley. I would put a scope on it first but I can’t imagine why it would prevent the engine starting, try cold starting it with the cam G40 unplugged to prove the point. The crank speed or position sensor would but the speed sensor failing would stop it whilst running.

[quattro estate]

It won’t start at all now unless I use a little easy start? I’ve not got a scope but I will try cranking with a led light soon hopefully that will confirm if the cam sensor is operating
if a previous comment is right that the crankshaft sensor doesn’t starting functioning until the engine is above 28rpm.
I’m unsure of any other fault at this time
fuel delivery/presuure appears to as it should?
thanks for your input ?

[Tractor Dave]

If the battery is weak and not spinning the engine over quickly enough, it won't start. Test the cam sensor with led and if good i suggest you read the very good post by Urs4boy. Shame he isnt a visitor these days. He knows his stuff.
https://www.s2forum.com/forum/genera...wn#post1077635