944S2 Hot Start Issue

[Frenchy]

posting for a friend as post, hot start issue on a late model S2, the eng temp sensor has been changed along with DME, he thinks he can smell fuel so possibly running rich which the temp sensor should have sorted.
Any Ideas Peeps ?

 

[bmnelsc]

posting for a friend as post, hot start issue on a late model S2, the eng temp sensor has been changed along with DME, he thinks he can smell fuel so possibly running rich which the temp sensor should have sorted.
Any Ideas Peeps ?

When this comes up on the PCNA forums the trouble is often attributed to vapor lock created when the fuel rail looses pressure (normally fuel rail should maintain pressure for 20 - 30 minutes after shutdown). Problems can be pressure regulator, fuel damper, check valve in the fuel pump (integrated - not a separate component on later models like the S2) or even an injector leaking slightly. The test is to put a pressure gauge on the fuel rail and monitor pressure after shut down on a hot engine.
I had similar problems on my S2. Intermittent - really depended on how long it sat after being shut off, where it would start up reasonably well but barley run for up to a minute. If it sat for a few minutes on a hot day it would have problems but if left until the engine cooled down some it was ok. The problem seems to have cured itself for me so probably lightly leaking injector finally cleaned by my use of additive rich premium fuels. I also started fueling more often with less gas to keep the fuel fresher and "turning over" more.
My advice is to add a healthy dose of fuel injector cleaner to the fuel for a tank or two while giving it a good run. You could test the pressure first and try this as a "fix" or just start here and see if the problem goes away.
If you do test and find a pressure drop then determining the problem is more involved. Checking injectors means pulling the fuel rail with injectors attached, put some paper towel under each injector and then cycle the fuel pump to build pressure. Hopefully the paper towel stays dry. Not sure of the procedure to check the other components individually but cheaper to test rather than throwing parts at it.
Good luck.

 

[Frenchy]

Bruce, thanks great reply, I will pass it on to Dave, fuel cleaner additive first then move on regulated, damper etc.

 

[robwright]

My vote would be with the fuel rail also mate.

 

[Frenchy]

Cheers fella, seems to be more common now due to age no doubt, time to stock up on fuel related bits.

 

[colin944]

I had this problem with my S2. I changed the fuel pressure reg, damper , DME relay , DME temp sensor all to no avail . I then put a couple of bottles of injector cleaner though it of a period of time and it hasn't done it since.