Porsche Enthusiasts Club Forum

944 s2, starts fine when cold, but when I go for a spin and turn the engine off for about 10 mins, come back to it and the starter spins fine. But it takes more turns to get it going ( and didn't start at all at one stage). Had a look a air filter (k&n) and one end was dirtier the other so I just span it round for now. I also checked the plugs, which are the right colour.Insidently there was what looked like a piece of rubber stuck round one of the plugs which I assumed was a part of a spark plug socket that someone had left on a previous plug change. I suspected that this was not letting the ht lead sit properly on the plug. After a test drive the car runs much better and feels at full power. But still hard to start when hot.
Any ideas anyone?

On another note there was oil down the bores on top of plugs 1 and 4, could that be a leaky cover gasket or something and the oil is dripping down onto them?
Cheers

Oil most likely the cam cover middle gaskets leaking

My money is on the hot-start valve on the fuel pump starting to weep and not holding fuel under pressure. I have the same problem and am putting off repair whilst is so cold and wet outside....

Do a search and you will see that Jon described a while back how fuel under pressure will not evaporate as quickly as at the lower pressure that occurs when the valve leaks fuel back by the return pipe. Because it has evaporated due to a hot engine when you come back then ten minutes later it takes longer to drag fuel back up. If its only five minutes since you last switched off then evaporation hasn't taken it all away and the car starts. Of course the problem is even worse on a hot summers day.

Well that's my understanding of it all anyway

Cheers Rob

Sounds simple enough. I'll have another look in a couple of weeks to see if the oil is back. Cheers

Trying to find it, but no joy. What are the best ways to find it?

AhHa!

It would help if I had called the valve thing by the right name! Fuel check valve - not hot start valve!

here you go:

http://forums.tipec.net/viewtopic.php?f=25&t=15176&hilit=fuel+check+valve

Could it be a DME relay? sounds as if you should always carry a spare by the sounds of things. The Clarkes Garage site is very informative, v impressed.

Someone in the know told me that hot start problems can be battery related. Try a different (new) battery? (long shot from someone who knows little).

Battery is pretty new and it has an indicator on the top to show if it needs charge. Just resoldered the dme relay, so I'll see if that makes any difference. The only thing is the dme relay didnt look old and looks in good condition

I understand the DME Relay can be affected by heat whether new or old.... although a 10min run shouldnt get that area too hot... the Clarkes Garage emergency fix using a jumper cable between 30, 87 and 87b could tell you if its the relay or not. It hot starts using the jumper, its likely a relay problem. If not, the relay is fine....

Have just used this on my 968 in sorting problems on my own DME Relay electrical gremlin.

Hope this helps. Good luck!!

Well the soldering hasnt worked. Will try the emergency jumper wiring tomorrow.

Tried the Clarks Garage method of the emergency jumper and still no difference, when the pump energized I could hear fuel in the fuel rail. I does start, just not very well. when it does start, it labours and clings on at about 500 rpm (for 10 seconds) and gradually comes round to normal idle. If I blip the throttle it nearly dies. Suppose thinking about it, sounds a bit fuel starvation related. Does anyone know if the check valve on the pump is available to buy on its own? Any opinions gratefully received.

Cheers

Well, I've tested the check valve on the fuel pump by crimping the fuel line next to it on the outsise of the casing near the filter,

just after turning the engine off. Low and behold after waiting 10mins it started up as if it was cold.
So I'm looking to clean up the check valve. Before I tackle that the state on the banjo and bolt don't look the best

Is it best to replace the banjo and pipe to the filter, as they probably wont reseal very well or is it a case for just using new copper washers. Any advice much appreciated.
Suppose I could actually change the filter whilst im down there!?

When I replaced the pump on my 924 the banjo end looked more or less the same but after a quick bit of sandpaper action it turned out to be mostly surface rust. I painted them, put new washers on and it was fine.

More importantly I kept the one way valve of the old pump (long story but I kind of broke the pump) and the valve was fine. Let me know if it would be of use?

Thanks

Ok cheers, I let you know.
Is that the check valve, the silver bit he banjo goes onto?
Also, any idea what size the washers are?