'88, 80 Quattro, fuel probs. long

["Tilden, John" <tilden@data-io.com>]

So lets see if I can get this right:
I'm working on Tess's '88 80 Quattro, you may have already seen our hasty 
post
from last night, sent in panic mode!

Tess's Quattro has developed a nasty habit.
It Starts and runs OK when cold, but after warming up, it starts fine, but 
will not run above 1200 RPM!

Other symptoms:
     1. Temperature Indicator in Instrument Cluster, seems intermittent!
     It will initially indicate cold even after 10 or so minutes of driving.
     Opening Hood, and disconnecting, reconnecting will cause the Temp
     Indicator to register, apparently correctly.

     2. After additional driving, the car will start it's bucking, will run 
and pull
     the car at idle and below 1200 RPM. Above that the Engine cuts out 
until
     the RPM drops below 1200 when it will run again, at low speed.

     3. Disconnecting the Pressure Regulator (differential P.R.) on the Fuel
     Control Unit  (KE3 style) the car will run fine in all modes.

     4. Measuring the current to the Differential Pressure Regulator, shows
     approx. 10 ma at idle, below 1200 RPM, when increasing the throttle
     opening to 1200, the current then peaks at about 50 ma, and drops to
     10ma, in concert with the galloping of the engine, sort of a sawtooth 
RPM
     profile 800 to 1200 back down to below 1200 etc.

     5. When disconnecting the Differential Pressure Regulator connection,
     while idling, the idle speed increases very slightly, and the engine
     smoothes out.

     6. Just prior to the system failing, under full throttle acceleration 
in 3rd
     gear, the car starts to develop a miss, then shortly after it fails, 
into
     the gallop at 1200 RPM. limping home at 15 MPH, in 3rd gear.

     7. The Temperature Sender looks OK, resistance cold, approx. 4Kohms,
     Hot, 500 ohms. medium warm, 2.5Kohms.

     8. Slight sign of fuel weeping from the connector on the housing of the 

     Differential Pressure Regulator. i.e., Red fuel residue.

     9. Computer diagnostic codes indicate checking the Temperature Sender,
     and it's wiring.

So what you all think? Anyone have a similar problem with your '88 or later 
80/90
Quattro? I will order a new Temp Sender, but I don't think it will fix the 
problem!

John Tilden
tilden@data-io.com