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Rod · Joined: 07 Jan 2008 Posts: 6 Location: Seattle

Had to pull the head to replace broken exhaust stud. Did the valves as well. Can't get started. Spark is good. Plenty of fresh gas & pressure on initial lines. Primed fuel system by jumpers at fuel pump relay. No gas going through fuel distributor to the injection lines. Tried cranking engine with 1/2" gap on throttle body. Need help troubleshoot getting fuel to injectors.

Thanks.
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Rod

Ozzie · Posted: Sat Nov 08, 2014 11:23 pm Post subject:

have you tried manually lifting the flap in the CIS
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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

Rod · Joined: 07 Jan 2008 Posts: 6 Location: Seattle

Thanks for your quick response. I'm not sure of the procedure you describe. We've tired holding the butterfly on the Mass Air Flow while starting. It moves down about 8 mm. Car was running fine / no CIS problems before pulling head.
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Rod

Ozzie · Posted: Sun Nov 09, 2014 8:58 pm Post subject:

The butterfly? should lift up to increase fuel flow
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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

Rod · Joined: 07 Jan 2008 Posts: 6 Location: Seattle

Is there anything else that would stop fuel flow at the fuel distributor? It seems to be mostly a mechanical device responding to the MAF butterfly with fuel metering adjusted by air flow quantity.
Seems like there should be an electrical shut-off valve like VW diesel injector pumps have.
What dangers are there taking the fuel distributor apart to look for obstructions & do general cleaning with carburetor cleaner? I expect small port restrictions in the distributor similar to needle valves in a carburetor to meter the fuel reaching the injectors. New injectors - figured at 170K mi. time to replace; likely poor spray pattern.
Thanks again, Rod
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Rod

gerben1986 · Joined: 13 Mar 2008 Posts: 232 Location: The Netherlands

And did you check if the cold start valve is spraying when you try to start? I believe it should also spray some fuel to get it running. It's on the back of the intake-manifold.
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911SC - 1980

emoore924 · Joined: 13 Apr 2004 Posts: 2822

Assuming this is still CIS rather than a later added-on EFI setup (there is no MAF on CIS...)

Stuck fuel distributor piston.

So, in the fuel distributor, when you lift the air flap (the 4" round disc on the little arm that you can see when you remove the intake boot), that movement moves the piston in the fuel distributor and allows fuel to move to the injectors. When it gets crudded up, it doesn't move or sticks and that causes the symptoms you're describing.

If you're lucky, you might be able to free it up. If you take it apart, DO NOT DROP the little piston. It is tightly machined and you'll bend it, rendering it inoperable. Then you'll be in for a fuel distributor rebuild for sure.