starting problems when hot

porkynut · Jul 20, 2011

has anyone suffered with a problem of difficulty starting when the engine is hot.
After a 80 mile problem free journey i stopped for about 30 mins, went back to start the car and nothing.
engine turns over fine.
left it overnight and it starts perfect.

Pamela Rimmer · Jul 20, 2011

Hi, Not going to be a terribly technical answer this - I'll leave that to others, but I do know of this problem - not in my 968, but I have had exactly the same in a MKI VW Golf GTi,which was designed by Ferdinand Porsche incidentally, so has the same pedigree, and hence this same problem - Petrol starvation. It was caused by, I believe, the petrol lines running close to the very hot engine, and so the petrol in the lines evaporated once the petrol pump stopped, so when you tried to start it again, there was no petrol in the lines, which meant you had to turn the engine over quite a few times in order to pump enough petrol through to fill the lines again, which is embarassing to say the least! When it cooled down or you started it from cold it was fine! I haven't had this with my 968, but we do have it with the 1984 911 Carerra, haven't had it with the 993 either to be honest. I know that there is a fix for it in the 911s, but not sure if it will be the same in the 968, possibly the more technically able of our membership can tell you. I am probably going to be shouted down with my theory as it may not apply to 968s, however I thought it was worth mentioning, just in case it helped! Hope you get it sorted.

porkynut · Jul 21, 2011

Thanks Pamela, i am sure no one will shout you down and i had similar thoughts to heating of fuel lines.
perhaps someone will reply with a more technical answer and a fix.

Oily · Jul 21, 2011

How old is your fuel pump DME relay. I understand that these can be affected when the engine is hot. Make sure yours is the later one starting 993.xxxxx, not the one starting 994.xxxx. They can be obtained through the usual 968uk vendor.

paulf968 · Jul 21, 2011

In addition to the above, my 2 pennyworth is:
- a fuel injector that is sticking slightly open can lightly flood the engine when switched off, making it difficult to start -- try injector cleaner and some fresh Shell V-Power through the engine to clean it.
- electrics are a weakness for me but I am sure there is a stat or idle control thingie in our cars which should function each time it is started - you may need to get your car hooked up to some Bosch diagnostics to identify the issue.

good luck

Neil Haughey · Jul 21, 2011

Crank angle sensor is another, certainly on my S2 its fixed the poor to non-existent hot starting as a side effect of trying to cure the cutting out problem it had.

Swindon_Mick · Jul 21, 2011

+1 for the DME relay - had this problem on my old 944 and a new DME relay solved the problem

Mick

porkynut · Jul 22, 2011

Thanks for the advice to date.
DME relay sounds like a good starting point though and maybe a check of the other suggestions.

paulf968 · Jul 30, 2011

........... did you sort it?

Fraser · Aug 2, 2011

Late to the party again (sorry) I had the same problem on my 968 - fixed it by getting the starter motor reconditioned. As a short term fix I stuck the car in gear and rocked it when it was hot if it wouldn't start. Happened all of three times, but dashed inconvenient.

Sorry - just re-read OP that car turns over - please disregard this reply. oops. [8|]