74 US Carrera WUR advice and graph needed

drvee12 · 09-22-2022, 03:10 PM

While waiting for a buyer of my 2.7 motor ( listed on Pelican here ):

F/s 2.7 cis engine complete

I decided to try my luck at solving the running issues of this motor as its definitely fuel system / CIS related. Bought a pressure test kit, and began the process. First thing I find is the Warm Up Regulator on this motor is not listed in any of my factory manuals, so I am unable to locate a graph for control pressures. Does anyone know if this WUR is correct for a 74 US Carrera: 043 8140 129. All of my books say it should be 0438 140 009 for vacuum controlled regulator but some online sellers list the 129 as well for a 74.

The cold control pressure is 3.7 Bar so its either the wrong one or defective…..
( System pressure is OK at 4.5 )

Pelican collective wisdom appreciated.

fanaudical · fanaudical's Garage

The 009 is for, I think, a '75 S motor. What are the part numbers are the fuel distributor?

Zuffenwerker · 09-23-2022, 09:36 AM

CCP for the 129 should be 1.8-2.3 bar @20c.

I believe the correct WUR for your car is the 001 used from 73.5 to 75. That’s what is in the 1974 Porsche spec book and workshop manual.

drvee12 · 09-23-2022, 09:54 AM

Correction, my current WUR does NOT use a vacuum port.

The Fuel Distributor currently on the engine is 0438 100 004 / 4843 325. Since this is an unstamped replacement motor from the 80's, maybe that will help identify the actual year and model of this engine ?

RarlyL8 · RarlyL8's Garage

-004 FD is correct for 2.7L engine '74/5.
-009 WUR is correct for the 2.7L engine '74/5.
-129 WUR is the factory replacement for -001 and -008 units.
If it runs rich all of the time check the system and warm fuel pressure then electrical current to the WUR and fuel pump.

drvee12 · 09-25-2022, 09:49 AM

thanks, looks like the WUR on the car is a correct replacement for a 74 motor, so definitely a defective regulator, will get it rebuilt and see how it goes.

drvee12 · 09-25-2022, 11:13 AM

Before I start ripping into rebuilds, a bit of major confusion on test procedure. The fuel distributor on this car has a line going to the WUR, and a banjo fitting with a fuel line running to the
Pressure Regulator.

I see most CIS Pressure testing hookups online do not have that small auxiliary line going off to the regulator. My test kit comes with a fitting allowing me to include or exclude the line going to the PR. When using the CIS test procedure on this particular Fuel Distributor, should that line be hooked up to the test circuit or omitted? I get crazy results either way...