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Fixed the cold start issue and now this is happening...
Hi Pelicans,
So, I've recently managed to fix a cold start issue I had on my '76 911S Targa. The issue was that when the engine was cold, it would cough and splutter till eventually it would bare stay on without the starter being engaged until the engine would roar into life and have a lovely high idle. I believe the issue was that the thermo time switch was faulty, which I've replaced. It could also have something to do with a wire hanging off my starter motor... whoops  However, now I'm experiencing a whole new issue. I drive the car for say 30 minutes, get it up to temperature, life is good. When I turn the car off and let it sit for say 10/15 mins and try and start it again - it wont start at all. Not even a glimmer of hope. You have to engage the starter for so long, I worry i'm damaging it. You can also hear the battery fading. Then a splutter. It sounds like one cylinder is firing, then another, and another until finally she roars and is fine. So, has anyone experienced this? Why would this happen after I fix the cold start? Thanks in advance! |
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06-10-2020, 09:57 AM
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Sounds like a fuel accumulator or an inline check valve is failing. Suggest a fuel pressure decay test to verify. Should hold 1.1 bars after 30 minutes.
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Walt 82SC 3.0 81SC 3.6 |
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06-10-2020, 10:07 AM
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Hi..do some search on this form on fuel pressure leak...
I would start replacing your fuel pump check valve-This valve is there to hold the fuel prss.in the system when you turn off the engine for about 25 min. The next could be your fuel accumulator..and ofcourse the best would be to have fuel press.gauges to install into your fuel system and see what is up... Start with the fuel pump check valve for now...but see what kind of fuel pump do you have.. here some reading for ya Ivan Fuel pump check valve
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1985 911 with original 502 191 miles...808 198 km "The difference between genius and stupidity is that, genius has its limits". Albert Einstein. |
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06-10-2020, 10:09 AM
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76 911S Targa
Join Date: Oct 2010
Location: Idaho
Posts: 1,150
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Agree. This sounds like your fuel/air mixture is way off at startup. Fuel pressures are the place to start and require the use of a fuel pressure gauge properly mated to your warm up regulator (WUR) and fuel distributor. There are many helpful posts on this forum. Here is a short video that shows the basic idea. Once you verify correct fuel pressure you can move on to finding any air leaks.
https://www.youtube.com/watch?v=5OHTH5uKYMg
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76 911S, 2.7, Bursch Thermal Reactor Replacements, Smog Pump Removed, Magnecors, Silicone Valve Cover Gaskets, 11 Blade Fan, Carrera Oil Cooler, Turbo Tie Rods. |
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06-10-2020, 10:20 AM
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Here's a pic of my fuel pump. Can't seem to locate the inline check valve, perhaps its internal?
Thanks for all the responses so far. At least now I know what i'm researching! 
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06-10-2020, 10:23 AM
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It's almost certain that the accumulator is the problem.
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06-11-2020, 04:13 AM
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CIS troubleshooting...........
Check your residual fuel pressure. This is probably the culprit. Second, test the fuel pump for max. fuel delivery. Must be able to deliver at least 90 psi. Keep us posted.
Tony |
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06-11-2020, 04:30 AM
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