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1979 sc RUNNIG FAULT HELP

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HI,just joined seems like a friendly place to find some help.My 1979 sc 911 has been stood over winter and has developed a massive overfueling problem,neat fuel runs out of the exhaust.The exhaust is not blocked (yet).If I remove the fuel pump relay it runs for a short while,as it would.I have been in the motor trade for 10 years and have not come across this before.A fault with the injection unit but what?Can the cold start really cause such fueling? Many thanks for your time.Michael
 
Ziggy
Sounds like it could be something to do with the electrically operated cold start valve, this is a seperate fuel injector used to enrich the mixture on start up?
Method of checking from the workshop manual.
To check it out you need to undo two screws and remove it without disconnecting it from the fuel line or electrical harness.
Disconnect electrical connector from CDI (capacitor discharge ignition) unit.
Point valve into a transparent container.
Have a helper actuate starter while observing cold start injector spray pattern. The valve should spray in a even cone shaped pattern until thermo switch interrupts circuit.
An irregular spray pattern indicates dirty or faulty cold start valve.

Cheers
John
 
John may well have hit thenail on the head with the cold start problem, howver it could also be a leaky injector which has allowed fuel to constantly drip into the engine over a period of time. Either way if it does start you will be 'washing' the cylinders and pistons with petrol and thus rendering them useless. The oil will also be thinner and lose it's lubricating effect. I'm an enthusiastic DIYer but I'd be inclined to trailer this car to an Independent for bench testing of the parts and then change the oil a few times in quick succession after the problem is solved.
 
Hi,
I've heard of this scenario happening before. Check that the fuel metering head is not stuck in the wide open throttle position. (Air flap controlled) If the car has not been used for a few months the plunger inside the metering head can gum up and once the car fires up and the air flap rises to raise fuelling at the injectors it sticks in this position and totally over fuels...

Regards
Martin
 
Thanks to all with replies.Will try as suggested.I will follow my findings up with a post and hopefully some pics.Thanks again guys.
 
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