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McGyver · Posted: Fri Sep 27, 2013 10:56 pm Post subject: Cold start problems?

Ok... i had some problems with cold start with my 931. Sometimes it starts just like that... after turn of key but it also starts after for example 5-7seconds of starter turns, what could be wrong... depending it's completly random. sometimes car is not used for few days and starts perfectly, sometimes in next day starts hard... sometimes on next day starts right away. When hot/warm it starts great without any problems and long starter turning.
Oh... when it starts (no matter fast or with long starter turning) engine works fine and respond good for acceleration). Pulls good even cold - which I don't do ... just for test purposes only.
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931 82' - 5000km after full engine rebuild

SOLD: 924 81' N/A- with turbo gearbox "dogleg" - great but mysterious car

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morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

Bad fuel acumulator?
Maybe sometimes you dont have enough pressure in the system to start..
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McGyver · Posted: Sat Sep 28, 2013 5:22 am Post subject:

I'm not sure... thats because sometimes car didn't run for a week or even more days and starts right away after key turn... fuel accumulator don't keep pressure for that long as I know or maybe I'm wrong.
_________________
931 82' - 5000km after full engine rebuild

SOLD: 924 81' N/A- with turbo gearbox "dogleg" - great but mysterious car

www.mauser98k.internetdsl.pl - if someone like german rifles (English version avalible)

morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

As far as i know it should have a one way valve.
Try holding the fuel pump open before cranking for a while and see if the problem is still there.
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McGyver · Posted: Sun Sep 29, 2013 6:08 am Post subject:

I have to check that

as I use relay without that prime pumping function... that could be good idea. But for me strange is that it sometimes works sometimes not. The worst failure to fix.
_________________
931 82' - 5000km after full engine rebuild

SOLD: 924 81' N/A- with turbo gearbox "dogleg" - great but mysterious car

www.mauser98k.internetdsl.pl - if someone like german rifles (English version avalible)

morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

Have you noticed any relation between the outside temps and the occurence of the problem? perhaps when it drops below say 15°C the valve bits contract more and bleed fuel back..?

Also if its temperature related...maybe you should also do a compression check...and take out and re-install all the intake connections.
Why? well for example my car starts perfect in any condition..but when its cold outside...somewhere in the intake tract there is a part that contracts more than the other and there is a vacum leak..and until the engine bay warms up..the car sputters and it cant be driven properly.
_________________
Supercharger and EFI kits
https://www.the924.com

McGyver · Posted: Sun Sep 29, 2013 9:08 am Post subject:

I'm not sure

I have to notice that. I keep my car in garage when is normal room temperature so changes are not too high as I suppose.
Engine was rebuild just 5000km ago and don't take any oil, head was full rebuild so I don't think anything is wrong with that but I take car somewhere and check it.
_________________
931 82' - 5000km after full engine rebuild

SOLD: 924 81' N/A- with turbo gearbox "dogleg" - great but mysterious car

www.mauser98k.internetdsl.pl - if someone like german rifles (English version avalible)