924Board.org

[autoxman]

I've been working on getting my '82 924 (N/A) running for the winter. I have spark and compression but im not getting any fuel to the injectors. On top of that I really don't know how the whole mechanical fuel injection works. I know the pump is creating pressure because I had to replace the lines on either side of the fuel filter because they were spitting fuel out. I pulled one of the hard lines to the injectors off the dizzy and cranked it then but just barely got enough fuel out to get about a quarter size spot on the dizzy wet with fuel. Are there any common problems with the fuel dizzy and how does it work? Thanks
-Ben
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1995 Acura Integra GSR 4DR (DB8)
1993 Honda Civic DX
1982 Porsche 924

[Mike924]

Not come across this one before.

It seems to be that something in the fuel dist is blocked (assuming your filter is OK). The resultant back-pressure in the lines could be what caused them to leak.

I'd start be removing the pressure regulator on the side of the dizzy and giving it all a good clean. It could be that the rubber o-ring has 'melted' causing the blockage, so a new o-ring would be a good idea.

Also, what position was the air meter flap in when you did your fuel flow test? If it was close to the bottom of its travel, chances are not much fuel will flow.
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1985 Porsche 924 'Lux', Kalahari Beige (my ex)
1993 Porsche 968 Coupe, Midnight Blue, 6 spd

'There is no substitute for a little grease under your fingernails.' - Chrenan, 924board.org

[Stampedetrail]

If you're not getting fuel, try this: pull one of the injectors out of the head-- they simply pull straight up but you might need pliers if they've been in there for many years. Then pull the cover (the air plumbing that ends at the throttle body) off the top of the fuel dizzy so you can see the metering plate. It's about 4" in diameter plate that sits in a bowl-shaped cylinder.
The plate is connected to a valve that controls fuel pressure. When the plate lifts up, the valve opens. When the plate is down, the valve closes. There's a 3mm adjustment screw between the valve and plate that lets you set the mixture.
Pull an injector & place the end in a jar. With the key switched "on," lift the plate, which should activate the fuel pump & open the valve to the injector, making it spray fuel. If you have a later model 924 you might need to jumper the fuel pump relay to get the fuel pump to activate, or have an assistant crank the engine over. Fuel should spray from the injectors into the jar. If not, the problem is probably occuring before the fuel dizzy, or with the dizzy itself (a remote possibility).

It may be a simple matter of adjusting the 3mm allen screw at the fuel dizzy, or there could be some air or fuel leaks in the system preventing vacuum from lifting the metering plate.
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1977.5 924 "Martini" head / New Old Stock rebuild
1985.5 944 Why? Because I can.