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 Starting Issues 
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Granny Driver

Joined: Thu Oct 13, 2011 11:45 am
Posts: 26
Location: Denver Colorado
Post Starting Issues
Currently I am having issues with my 928 starting. Here are the details: When the care sits overnight it will fire right up in the morning. If I drive it for a while and turn it off but start it within about 5 minutes it will start back up. But If I wait 10 minutes to 2-3 hours it will take at least three to four tries and sometimes more get it started. Even when it starts it is sluggish and I have to feather the gas to get it going. When it finally starts it sends a puff of smoke out of the tail pipe after and during the starting process.
What I have tried so far is to wait before starting and just have the key turned for 30 secs. I have pumped the gas before and during the start up process. And I have also tried just starting it with no gas pedal assistance. The only way it will start is if I give it gas during cranking.
Per my “Running Rough” post I have done several things. To include new fuel lines, O2 Sensor, New vacuum hoses, spark plugs, new battery, cleaned the intake, adjusted the MFA and it has a new K&N filter. Probably other stuff but that is all I can remember.
I would love to get this running so I can drive it everyday.
Thanks

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Jay

81 Porsche 928
95.5 S6 Wagon
00 S4
72 Audi 100 LS


Tue Oct 25, 2011 9:31 am
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Location: Sunny San Diego
Post Re: Starting Issues
In the right rear wheel-well behind the forward panel, there is an Accumulator in some years. They leak and cause hot start issues. I would at least there and see if all looks ok.

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1981 Porsche 928 "Euro" 4.5 Litre Auto Gunsmoke Metallic Flat - Black Interrior
1983 Porsche 928S "US" 4.7 Litre Auto Light Bronze (Copper) Metallic - Brown Interior


Tue Oct 25, 2011 12:48 pm
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Granny Driver

Joined: Thu Oct 13, 2011 11:45 am
Posts: 26
Location: Denver Colorado
Post Re: Starting Issues
Ok so I looked in the wheel cover and there is not an accumulator. There is a plastic small filter looking device but that is all. Is there a chance it is located in another place or is there something else that I should check? Thanks for the help.

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Jay

81 Porsche 928
95.5 S6 Wagon
00 S4
72 Audi 100 LS


Tue Nov 01, 2011 8:52 pm
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Joined: Mon Jan 07, 2008 8:43 pm
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Location: Sunny San Diego
Post Re: Starting Issues
Yeah, some models don't have one. Can you take a pic of what you see? Have you gone through all your grounds, 14 Pin cleaning? I still think you have a fuel pressure issue, hence why I mentioned the Accumulator.

Post pics please.

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1981 Porsche 928 "Euro" 4.5 Litre Auto Gunsmoke Metallic Flat - Black Interrior
1983 Porsche 928S "US" 4.7 Litre Auto Light Bronze (Copper) Metallic - Brown Interior


Wed Nov 02, 2011 7:42 am
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Granny Driver

Joined: Thu Oct 13, 2011 11:45 am
Posts: 26
Location: Denver Colorado
Post Re: Starting Issues
Do we think that a faulty fuel pressure regulator could be the culprit? I just took some and will put some up this evening. I did notice when I had the fuel and vacuum lines taken apart that fuel was coming out of the vacuum lines end of the fuel pressure regulator. I think this could be causing an issue unless fuel should be coming from there?

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Jay

81 Porsche 928
95.5 S6 Wagon
00 S4
72 Audi 100 LS


Wed Nov 02, 2011 9:23 am
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Joined: Mon Jan 07, 2008 8:43 pm
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Location: Sunny San Diego
Post Re: Starting Issues
Your leaking somewhere and that is a good indicator. Replace it, sounds dangerous too.

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1981 Porsche 928 "Euro" 4.5 Litre Auto Gunsmoke Metallic Flat - Black Interrior
1983 Porsche 928S "US" 4.7 Litre Auto Light Bronze (Copper) Metallic - Brown Interior


Wed Nov 02, 2011 9:28 am
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Speed Limit Obeyer
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Joined: Thu Mar 17, 2011 7:37 pm
Posts: 71
Location: Van Nuys, CA
Post Re: Starting Issues
Fuel present in vacuum lines is the failure mode for fuel regulators and dampeners showing that the vacuum diaphram is broken, id check each regulator at the rear ( i think yours has 2 like mine) and the front dampener indivdually to isolate the failed devices, unless you wish to replace all of them at once which couldnt hurt. test vacuum w/ a mitty vac, should hold up to 20 psi for minimum 2 minutes if i recall. if you wind up changing both regulators, 928 specialists and motorsports i think sells adjustable ones if your into tuning your fuel system later down the road. i recall 928specialists recommending using a single adjustable FPR and switching the other with a fuel dampener so there is only one single point of regulation to the return line. See: http://928gt.com/pc-400-3-adjustable-fu ... 80-87.aspx
Fair warning though, you will need more diagnostic equipment for this route to make sure its in the desired spec (wideband o2 sensor and fuel pressure gauge). OEM will already be in spec so its just hook up and go.

Best of luck,
Jonathan.

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Porsche 928S - 84 (Quartz Grey Metallic)
Automatic
Euro Intake manifold/Cams/Injectors, Headers
Left to do/fix: Sunroof,electric locks,some interior, paint body,replace hood lining, bad gas milage
A little of a fixer upper, but a labor of love!


Wed Nov 02, 2011 12:19 pm
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Granny Driver

Joined: Thu Oct 13, 2011 11:45 am
Posts: 26
Location: Denver Colorado
Post Re: Starting Issues
Thanks for the help. This is what I have located so far. When the car is idling it fluctuates a little but when I unplug the II hose as shown in the picture the idle goes steady. So I unplugged the hose (which I thought was a breather hose) and left it off and fuel started to drip out of the hose. Am I right to assume that fuel should not be coming out of the hose?

My thought is that a hose (which lead to a three other hoses ) is sucking fuel in and putting fuel into the throttle housing and thus messing up the starting? What does the fuel injection pressure regulators do? I know 2, 3, 4 hoses should connect but should hose 1 be connected to them also? By the way the third picture is from a link MpDano sent me and it is not my car but it looks the same.


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Fuel Breather hose locations.JPG
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Fuel.jpg
Fuel.jpg [ 1.13 MB | Viewed 1117 times ]

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Jay

81 Porsche 928
95.5 S6 Wagon
00 S4
72 Audi 100 LS
Mon Nov 21, 2011 10:18 am
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Granny Driver

Joined: Thu Oct 13, 2011 11:45 am
Posts: 26
Location: Denver Colorado
Post Re: Starting Issues
It has been solved. I replaced the fuel regulators and it works like a champ. I have not been too motivated to work on it because of the weather.

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Jay

81 Porsche 928
95.5 S6 Wagon
00 S4
72 Audi 100 LS


Mon Jan 09, 2012 12:44 pm
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Joined: Mon Jan 07, 2008 8:43 pm
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Location: Sunny San Diego
Post Re: Starting Issues
Excellent! Thanks for following up on your topic. Let's hope for warmer weather for you.

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1981 Porsche 928 "Euro" 4.5 Litre Auto Gunsmoke Metallic Flat - Black Interrior
1983 Porsche 928S "US" 4.7 Litre Auto Light Bronze (Copper) Metallic - Brown Interior


Mon Jan 09, 2012 2:07 pm
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