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brealytrent · Joined: 28 Dec 2008 Posts: 414 Location: Goldsboro, NC

The Mixture Adjusting Screw got messed up and is now way out of adjustment. Do you know the factory setting of the screw so I can try to get it set to the right mixture? (so-and-so many turns left/right?)

Joes924Racer · Posted: Sat Aug 15, 2009 4:14 am Post subject:

That really doesnt work, ya gotta go hunt down a shop that has a machine to set the mix hopefully he has a tail pipe tester that checks parts per million. You could set it your self though its a crap shoot without the equipment jus do it till it doesnt blow black sooty smoke when reved..
_________________
1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

emoore924 · Joined: 13 Apr 2004 Posts: 2822

I just went through this exact situation. I had no idea what the mixture setting was. The car did not run. Based on advice from the board, here's what I did...

Disco battery (-) lead

Jumper fuel pump relay.

I turned the fuel mixture adjusting screw all the way CCW (lean). For me, it was like EIGHT turns. That's a whole lotta turns for something where 1/4 turn can make it go from great to terrible.

To clarify, the mixture adjusting screw is accessed by inserting a tiny allen wrench into a tiny port next to the fuel dizzy and the air-fuel flapper-thingie. (Flapper-thingie heh heh, that thar's technical jargon, son).

Carefully crack a banjo bolt at the fuel dizzy for one of the four fuel lines going to an injector. Have a rag handy to sop up any spillt fuel. Allow the fuel pressure to bleed out. Depending on how long ago the fuel system was last pressurized, it will drip anything from a few drips to a couple of CC's of fuel.

Remove the banjo bolt. Don't drop the little copper sealing washer(s). You should see a little fuel puddling in the hole.

Have an assistant ready at the battery. Be sure assistant has fire extinguisher handy. (You too, unless you can run faster than assistant...)

Do the following very carefully. You are working with fuel.

Have assistant touch (-) lead to battery. You should hear the fuel pump start. *Nothing* should happen at the hole in the dizzy. If fuel comes out, STOP! You have a problem with a sticking control plunger in the fuel dizzy and you ain't gonna fix that with the adjusting screw.

Slowly, carefully, turn the mixture adjusting screw CW. Do not push down on the allen wrench into the hole. Just turn it slowly. Turn until you see the fuel just start to swell from the port in the fuel dizzy. Have assistant immediately remove (-) lead from battery.

Reconnect fuel line. Remove jumper. Replace relay. Connect (-) lead. Start car

Check for leaks.

That should get you close enough for the car to run. Set your ignition timing. Then you'll need to take it to your favorite local mechanic (the one with the emissions tester) to have it dialed in so it actually runs right.

datatrain · Posted: Sat Aug 15, 2009 7:10 am Post subject:

Wow !!! you do sparky stuff under the hood with an open fuel line. That's a recipe for disaster. If you search here you'll find a safe procedure that 's simple and it works.

To paraphrase....
Make a test lead from a few feet of zip cord. Put a switch on the end and spade lugs on the other. Plug into the fuel relay socket and have the switch in your hand. Close the AF adjusting screw. Put your ear near the adjust screw hole and press the switch while you turn the screw open slowly. You'll hear the fuel start moving. Stop ! You should be able to replace the relay and start the car. Typically on mine that's about 1 1/2 turns more or less.

Now you also have a test lead for future troubleshooting.
_________________
'78 924 NA with Collector plate
33 year old car, with me for 21 yrs
Mint '92 318i BMW
Near mint '98 Buick LeSabre
VE7HFR

emoore924 · Joined: 13 Apr 2004 Posts: 2822

Yeah, well if you blow yourself up with two drips of fuel I think you need to have your head examined.

datatrain · Posted: Sat Aug 15, 2009 1:13 pm Post subject:

Try and remain calm, I was just suggesting there is an easier way to achieve the objective. Sorry if I offended you.
_________________
'78 924 NA with Collector plate
33 year old car, with me for 21 yrs
Mint '92 318i BMW
Near mint '98 Buick LeSabre
VE7HFR

Vince Ponz · Joined: 02 Nov 2002 Posts: 3581 Location: Florida

Have your wife/girlfriend/lover hold the fuel lines and stand back.
_________________
"Never let them see you sweat"
77.5 924 modified track car
79 931 Euro stock
88 924S SE
87 911 Targa stock

brealytrent · Joined: 28 Dec 2008 Posts: 414 Location: Goldsboro, NC

I must give kudos to Emoore924. I did what you said, except just turned the car to the on position and pushed up and the arm inside of the air box where the air filter goes. I got the mixture set now.
In addition, why is everyone so afraid of gasoline? Jeesh, it's not like the car is a $100,000 german cuckoo clock! I've spilled lots of gasoline with this car and no explosions have ensued.

El Chato · Joined: 22 Aug 2006 Posts: 205 Location: El Paso, TX

yeah those are the good ways porsche also says to get the starting mix, I suggest hunting ebay for a gunson exhaust gas analyzer, works great and the mixtrue just rigth, although it takes some time, like an hour or two, between calibrations, I went from 15 m/g to 27
_________________
1979 924 N/A, Snail Shell
1980 924 N/A
1976 924 N/A

It may be that your whole purpose in life is simply to serve as a warning to others.

Today's weirdness is tomorrow's reason why.

Paul · Posted: Mon Aug 17, 2009 11:08 am Post subject: