TheBaywatchKid Posted 13October, 2020 Report Share Posted 13October, 2020 I bought my SC about a month ago, knowing that it had a warm start issue. If it was within a few hours of me running it, I would try to start, and it would just crank and crank and never start. The only way I could get it started, was to pop the engine cover, and manually flip up the air dump valve. I suspected Fuel accumulator, given it only was an issue when warm. I'm still very new to 911's so my diagnosis skills are rudimentary. My mechanic tested the fuel pressures, and it was indeed not holding fuel pressure. I had the fuel accumulator replaced and now there is no issue with warm starts. On warm starts, it fires immediately and it idles around 900. The issue now is that on cold starts, regularly the car will crank for quite a while, and then splutter and start after 4-5 seconds. Still have not had it never start, but nearly every time on cold starts now it takes a while to fire up, and it seems to be taking longer to fire over time. In terms of what I should be doing, I assume buy a fuel pressure test kit, and test all 4 pressures as per https://www.pelicanparts.com/911/technical_specs/Testing_Bosch_CIS.htm Check fuel filter. Anything else? Thanks in advance! Looking forward to getting my hands dirty in this. Quote Link to comment Share on other sites More sharing options...
Dreamr Posted 13October, 2020 Report Share Posted 13October, 2020 Just as a possible quick fix ... When I started my SC, I would turn on the ignition (dash lights on) and wait till the radio came on (only a couple of seconds) ... this gave the fuel pump a chance to “charge” the system. I had the same hot start issues as you and fixed it the same way you did. With my few second delay starting procedure, I never had a cold start issue. Worth a shot at least ..... 😁 Quote Link to comment Share on other sites More sharing options...
TheBaywatchKid Posted 13October, 2020 Author Report Share Posted 13October, 2020 A free solution, definitely worth a try. Will give it a go and report back! Thanks @Dreamr! Quote Link to comment Share on other sites More sharing options...
TheBaywatchKid Posted 19October, 2020 Author Report Share Posted 19October, 2020 Tried this, unfortunately no change. Thanks for the suggestion though! Dreamr 1 Quote Link to comment Share on other sites More sharing options...
Merv Posted 20October, 2020 Report Share Posted 20October, 2020 I assume that all earths are great. I always add an additional one to the body and ensure there is no resistance within the one from the starter to the body. I have lost track of how many problems result from inadequate earthing. Most problems are electrical. There is the possibility that the WUR (Warm up Regulator) is faulty. Can you hear the fuel pump working before start? Are all the vacuum lines connected correctly? On the fuelling side, there is a parallel thread on the Pelican https://forums.pelicanparts.com/porsche-911-technical-forum/1075779-1980-911sc-targa-cold-start-issue.html Quote Link to comment Share on other sites More sharing options...
TheBaywatchKid Posted 20October, 2020 Author Report Share Posted 20October, 2020 25 minutes ago, mrar said: I had a similar problem on my 78sc. Ended up being a dodgie terminal on my starter motor solinoid (this terminal supplies power on start to enable extra fuel when cold) . It had disintergrated inside the housing not allowing the coldstart injector to supply initial fuel squirt on cold starts. New recond starter motor with correct terminal setup solved the problem after many hours of looking elsewhere. Maybe same for your 82, worth a look. Great to know. Is there a way you can identify the dodgy terminal? I'll have a look around the starter motor and see from there! Thanks a lot! 9 minutes ago, Merv said: I assume that all earths are great. I always add an additional one to the body and ensure there is no resistance within the one from the starter to the body. I have lost track of how many problems result from inadequate earthing. Most problems are electrical. There is the possibility that the WUR (Warm up Regulator) is faulty. Can you hear the fuel pump working before start? Are all the vacuum lines connected correctly? On the fuelling side, there is a parallel thread on the Pelican https://forums.pelicanparts.com/porsche-911-technical-forum/1075779-1980-911sc-targa-cold-start-issue.html Okay will check the resistance on the earth line to the body! Yep I can hear the fuel pump alright. I will check the vacuum lines, is that mainly from the WUR? Yes i saw this thread! Their engine does have the same cold start issue, but theirs always cuts out, which mine doesn't ever, so I initially discounted it but im going to keep an eye on it. Thanks a lot! Quote Link to comment Share on other sites More sharing options...
Merv Posted 20October, 2020 Report Share Posted 20October, 2020 The WUR and O2 relays just get old and eventually need replacement. To test the starter grounding put your Ohm meter on the starter earth terminal and on a clean body earth point. There should be minimal resistance. Ignition switches also can tired with age but this doesn’t sound like your problem. Always a good idea to clean all earth connections as well. However, the are all just standard preventative measures and the problem is probably the cold start valve operation (start enrichment valve). It is a likely culprit. See the diagram in the link below of the valve and its connections. https://dorkiphus.net/porsche/showthread.php?t=24552 TheBaywatchKid 1 Quote Link to comment Share on other sites More sharing options...
TheBaywatchKid Posted 27October, 2020 Author Report Share Posted 27October, 2020 On 20/10/2020 at 13:52, Merv said: The WUR and O2 relays just get old and eventually need replacement. To test the starter grounding put your Ohm meter on the starter earth terminal and on a clean body earth point. There should be minimal resistance. Ignition switches also can tired with age but this doesn’t sound like your problem. Always a good idea to clean all earth connections as well. However, the are all just standard preventative measures and the problem is probably the cold start valve operation (start enrichment valve). It is a likely culprit. See the diagram in the link below of the valve and its connections. https://dorkiphus.net/porsche/showthread.php?t=24552 Awesome, thanks a lot mate. Will give it a look over this weekend and see if i can isolate to the cold start valve! Quote Link to comment Share on other sites More sharing options...
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