924Board.org

MN-Michael · Joined: 10 Jun 2005 Posts: 2 Location: Minnesota, USA

I have a 1979 924 that has not been run since the early 90's. I want to flush the fuel system to remove any varnish build-up and make sure that the fuel lines, fuel distributer, and injectors are clean and working well before I even attempt to start the motor. I read a post about a year ago, about the flushing process, but can't find it again. I want to know if someone can give me a good step-by-step of this process. I have never flushed a fuel system before and am an average mechanic that can follow the book and perform most things. I planned to bypass the starter using the jumper process described in the Haynes Manuel for testing the fuel pump (after disconnecting the lead to the alternator) so I can run the fuel out with the fuel pump. I read on a post in the past that someone used acetone to clean the system, but I don't know if I should run that through the fuel pump. What I do recall from the previous post is to run the fuel with cleaner/acetone through the fuel line to the fuel filter up by the motor. Disconnect the line by the filter and run until clear, then continue step-by-step through the fuel lines, fuel distributer, injectors. Any tips or tricks that others have used would be great as I attempt this process. I would like to avoid pulling the gas tank.

Ozzie · Posted: Fri May 26, 2006 12:37 pm Post subject:

A few people put a filter on the low pressure line between the tank and external pump.
Not a bad idea if you want to protect the pump and you can drain and flush the tank at the same time.
Remove the injector lines.
Bypass the puel pump relay and run the fuel pump with fresh fuel and injector cleaner in the system.
After flushing the lines remove the injectors.
Reconnect and check the spray pattern.
Clean them if blocked.
Refit and that should be it.

If I have forgotten anything I'm sure people will add to it.
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

doomer77 · Joined: 10 Jan 2006 Posts: 266 Location: Huskvarna, Sweden

regarding the fuel dizzy, would spraying some WD-40 through the air intake plate dislodge crud in there?
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Why drink and drive when you can smoke and fly?
Carpe diem. and if that doesnt work; get drunk!

1980 924 n/a - engine swap begun
1989 Volvo 480ES

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

I would drain the tank by removing the internal pump (or screen if your 79 doesn't have the internal pump). You might get some sediment to drop out of the bottom of the tank that way. Then, with the internal pump still out of the bottom of the tank, pour clean fuel into the tank to clear out anymore sediment. Then install the internal pump again and reconnect your hoses and fill the tank with clean fuel. Then put your key in the ignition and turn it to "on" but don't run the car. Remove the injectors but leave them attached to the fuel lines. Place all the injectors in a large bucket. Take the rubber boot off the air meter plate housing and lift the metering plate by the nut in the centre. This will cause fuel to flow through the system and out the injectors, do this for a while, and then change the fuel filter.
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1987 951 - M193 Version for Japan

MN-Michael · Joined: 10 Jun 2005 Posts: 2 Location: Minnesota, USA

Thanks for the prompt responses. I will try to get to this soon and will post back how it went.

Michael
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1979 924
Ext: Mexico Beige
Int: Brown Vinal
Condition: Last ran early 1990's
St. Cloud, MN, USA

Paul · Posted: Sat May 27, 2006 10:50 am Post subject:

Do this outside and have a couple of fire extinguishers nearby.
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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.

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Very good point Paul. Any fuel related job for me usually results in me taking a bath in gasoline.
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1987 951 - M193 Version for Japan

D Hook · Joined: 02 Nov 2002 Posts: 3158 Location: Omaha, NE

If you find rust, you really might want to drop the tank and have it serviced. It will only continue to be a problem.

Also, I don't know if you want to FILL the tank. If you get into a situation where you have to empty it again, you don't want to have to drain more than a few gallons. And don't do like some guy in the newspaper did; he was draining his gas tank from his car, dumping the fuel down the toilet in his basement right NEXT TO HIS WATER HEATER! Blowed up real good!
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'80 924 n/a SOLD