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Hot start issue

 
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Mbean  



Joined: 11 Jul 2020
Posts: 9
Location: Maine

PostPosted: Fri Aug 16, 2024 12:11 am    Post subject: Hot start issue Reply with quote

My 931 has the hot start issue. I’ve replaced the accumulator, check valve, had vacuum lines replaced and it has new injectors. Starts great cold, runs really well but 15 minutes after shut down it doesn’t want to start. The funny thing is it starts great cold with the cold start valve disconnected. Does this make sense? System and running pressures were within spec when tested by my mechanic.
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BauerR  



Joined: 13 Apr 2022
Posts: 15
Location: Baltimore, MD

PostPosted: Wed Sep 11, 2024 10:21 am    Post subject: Re: Hot start issue Reply with quote

Mbean wrote:
My 931 has the hot start issue. I’ve replaced the accumulator, check valve, had vacuum lines replaced and it has new injectors. Starts great cold, runs really well but 15 minutes after shut down it doesn’t want to start. The funny thing is it starts great cold with the cold start valve disconnected. Does this make sense? System and running pressures were within spec when tested by my mechanic.




Makes perfect sense. You have way too much fuel at idle/start-up in hot start conditions.
Hot start issues usually stem from the idle fuel mix being too rich at the air meter.
I would back off the idle mix screw a full turn and see if that helps.
If you don't know, it's located i the air meter, to the left of the filter elbow. It requires a 3mm hex head to adust,
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996 Turbo ('04)
911 Turbo 930 ('84)
928 S4 auto ('89)
928 S4 manual ('87)
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931 Turbo S2 ('81)
951 Turbo ('87)


Last edited by BauerR on Wed Sep 11, 2024 11:37 am; edited 1 time in total
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Mbean  



Joined: 11 Jul 2020
Posts: 9
Location: Maine

PostPosted: Wed Sep 11, 2024 10:43 am    Post subject: Reply with quote

Ok, that’s interesting. I recently discovered that if I hold the throttle down with the key turned on for 10 seconds or so it starts great. It mentions that in the owner’s manual.
Thanks!
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BauerR  



Joined: 13 Apr 2022
Posts: 15
Location: Baltimore, MD

PostPosted: Wed Sep 11, 2024 11:37 am    Post subject: Reply with quote

Mbean wrote:
Ok, that’s interesting. I recently discovered that if I hold the throttle down with the key turned on for 10 seconds or so it starts great. It mentions that in the owner’s manual.
Thanks!


Yeah, sounds like you need to tweak the idle screw.
Counter clockwise to lean the mixture. I checked, it's a 3mm hex
_________________
996 Turbo ('04)
911 Turbo 930 ('84)
928 S4 auto ('89)
928 S4 manual ('87)
957 Cayenne Turbo ('09)
931 Turbo S2 ('81)
951 Turbo ('87)
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