engine miss fire???

[nick3814]

My 1983 911sc has developed a curious random fault, I wonder if any of you guys know what it might be. I took it out the garrage yesterday, started first time as always, let it tick over for a couple of minutes whilst I got something out the garage and all of a sudden the engine stopped dead, tried to start it again, tuned over fine but wouldnt fire, tried again still wouldnt fire. Left it for 5 or 10 minutes, tried again fired straight away and settled to a nice smooth idol. Then when I was out driving twice the revs just died as if no power but then picked up straight away, any ideas?????????

 

[jerry911sc]

Well I don't know all the possible causes but it certainly could be water in the petrol. Even a tiny bit in the tank can do exactly what you describe.

Otherwise sounds like a fuel system (sender/ filter)/ injection system problem to me.

GL

 

[bones]

Nick, give me a call tomorrow if you don't get any futher but often the type of fault you are describing is due to an electrical component overheating and breaking down, then typically when the parts have cooled a little the engine will fire again, you need to establish a pattern for the faults behaviour to trace an intermittent one like this. Don't rule out fuses, relays, battery connections and the immobiliser if you have one. Most likely suspects to break down under load and cause the engine to die are the coil and the CDI unit.
if you think it's unlikely to be an electrical failure then fuel starvation is the next fault I'd check especially if the engine 'hiccups' and then continues to run. Try as an experiment running Redex (Halfords) Injector cleaner through the system and in fact all owners of fuel injected cars should use a bottle of this every month or so to maintain the system.