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RarlyL8 RarlyL8 is offline
Crotchety Old Bastard
 
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Join Date: Jan 2000
Location: Huntsville, AL
Posts: 13,409
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As you have stated, a sudden rich condition can only be too much fuel, not enough air, or a weak spark.

A CIS engine depends on the air flapper valve to mechanically meter the fuel.
The fuel head and WUR regulate the fuel pressure.
The dizzy regulates the spark.

I would first check the system fuel pressure and the warm pressure. The WUR may have a blown diaphragm causing the pressure to dump.
If that's not it check the spark of each cylinder.
Let us know what you find.
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RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8
Old 08-03-2007, 12:21 PM
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