924Board.org

Ponz · Joined: 10 Jan 2013 Posts: 229 Location: Florida

My 931 will start normally and run but will not idle. If I stop for a light it will stall. I pulled the plugs and they are almost new looking and I have had them
in for years.
I am suspecting my fuel pump or fuel filter.

Any Ideas.

vince
_________________
77 1/2 track car
79 931 Euro
87 911 Targa

emoore924 · Joined: 13 Apr 2004 Posts: 2822

Strange, I was just talking to a guy yesterday who had the exact same problem on another kind of car (jeep). Car would start, run at speed, but when he came to a light, it wouldn't idle and stalled.

Turned out the negative battery cable was corroded inside the casing and wasn't providing a good ground. Looked ok on the outside but was all rusted out inside.

So, its a silly thing to check but stick a jumper cable from the (-) terminal to the block and see if it cures the problem.

Ponz · Joined: 10 Jan 2013 Posts: 229 Location: Florida

Thanks for your help.
I just had the car painted Forest Green Metallic and I have not been able to drive it far.
I will use your method.

I personally think it is the fuel pump or the fuel filter. I pulled and cleaned the plugs and they are light tan and too clean therefore I suspect the above.

I need help with this one. Anybody?

thanks again,
vince
_________________
77 1/2 track car
79 931 Euro
87 911 Targa

joemac · Joined: 22 Apr 2013 Posts: 44 Location: SE Pa.

Check for leaking injector seals.
_________________
Race car: my favourite palindrome.
Porsche: my favourite race car.

Paul · Posted: Sat May 11, 2013 11:10 am Post subject:

Try a new filter and install it in the correct direction.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

Ian89C4 · Joined: 01 Apr 2011 Posts: 561 Location: North Carolina

I would think that if it was the fuel pump or fuel filter being clogged it would have issues at all speeds and would actually get worse the more load (going faster) that you put on the system.

Check the connections to your idle switch (one of the two on the bottom of the throttle body and IIRC the one on the top as well) to ensure that they are not corroded and the wires have not frayed. Also ensure that you hear a 'click' from all of the switches as you open and close the throttle body.

+1 on checking for vacuum leaks and the negative to the battery.

I would also try checking to see if the coil is pushing enough juice to the dizzy.

Don't know if any of this will help, but just stuff I would try.

Good luck!

Ian
_________________
Ian Edgerly
North Carolina

Current:
1981 924 SCCA/ChampCar Weissach Race Car ("Serenity")
1987 924S ChampCar Endurance Car ("Der Weg")
1980 924 Euro ("Wahala")

leadfoot · Posted: Sun May 12, 2013 10:13 am Post subject:

how old is the ignition switch too, when this wears it cuts out the motor too...
check you AAV isn't gummed up,
you could try opening up the air bypass on the throttle and run a slightly higher idle, this may help you diagnose the air or fuel problem... if it still stalls then it's most likely fuel... if it doesn't stall then it's most likely air...
stu
_________________
1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...

Ponz · Joined: 10 Jan 2013 Posts: 229 Location: Florida

It starts then after a little while it wants to die. It will run okay but lift off the throttle and it will die. I think it is a fuel problem. I pulled the plugs and they were too clean. Light tan.

I will check the fuel pump and filter first.

thanks all
vince
_________________
77 1/2 track car
79 931 Euro
87 911 Targa

Ponz · Joined: 10 Jan 2013 Posts: 229 Location: Florida

I drained the gas tank and the gas came out clean. No rust or dirt.
Replaced with new gas same problem.

I will try to replace the fuel pump and see what happens. At over 200 dollars it seems steep.

vince
_________________
77 1/2 track car
79 931 Euro
87 911 Targa

Grenadiers · Posted: Tue May 14, 2013 4:03 am Post subject:

Things happen with the lights off, and car in garage! However, try opening up the air screw on the throttle body and see if it idles. Also, the piston on the fuel distributor might be gummed up and not moving correctly. Check fuel pressure as well, and pull the FPR on the side, see if it's varnished. Do this before replacing the 'spensive pump.
_________________
'83 944 Track car.
'88 924S Track car.
'89 944 Turbo
2004 Winnebago Vectra monster RV
2012 Jeep Wrangler
2014 Kia Soul
2001 Ford F350 powerstroke

Ponz · Joined: 10 Jan 2013 Posts: 229 Location: Florida

Thanks everyone.

I will try the suggestions. I will probably ask again. Sorry to say this but I don't work on engines. I leave to the experts. I really appreciate the help.

When I lived in NY I had a guy who worked for a Porsche tuner and then he now has his own shop. He is in NY and out of range. He charged next to nothing. I walked him through an adoption as I have two boys who are adopted. I believe my NY friend used him also.

I don't like paying $100 an hour unless I have to. Sad I know but I worked long hours running my business and never got into the engine work.

thanks for your patience
_________________
77 1/2 track car
79 931 Euro
87 911 Targa

Ponz · Joined: 10 Jan 2013 Posts: 229 Location: Florida

I reread my post............sorry Paul Celenta I did not mention your name.
_________________
77 1/2 track car
79 931 Euro
87 911 Targa