The warm-up regulator PN 102353 [WUR], also known as the control pressure regulator, generates a secondary fuel pressure that sits on top of the plunger in the fuel distributor to offer resistance to its movement. It is located on the driver's side valve cover, just behind the oil filler cap. It can be identified by the two fuel hoses and grey electrical connector.
NOTE: There is a curved vent hose that comes off the top of the regulator, bends 90 degrees, and is left open to the air. This often causes concern to people unfamiliar with the system. (The hose is held on by a red clamp in the photo below). This is normal. It is a good idea to inspect that hose from time to time as small insects have been known to nest in the end of the hose.
This control pressure varies with ambient/coolant temperature. This causes the deflection of the main air metering plate to vary with temperature, causing the fuel distributor to furnish a richer mixture when the engine is cold. This pressure varies from around 25 psi up to 50 psi and can be measured directly at either end of the hose that connects the WUR with the top of the distributor.
This pressure test requires a gauge set that can be "tee'd" into the line between the regulator and the top of the fuel distributor. Instructions for the use of the gauge, and expected readings, are given in the Workshop Manual on pages D:02:01 and D:02:02. The gauge set can be purchased from common tool sources, ask for a "Bosch K-Jet Test Gauge".
Problems associated with the WUR are rough running when cold and generally lean operation, including backfiring or poor performance.
When cold, the vacuum connections cause the control pressure to drop under sudden acceleration to give an enrichment "spike" to avoid hesitation. If the vacuum hoses are not properly connected, or if there is a fault in the vacuum circuit (failed thermal vacuum switch, cracked hose, loose hose, missing or backwards delay valve) the car will be almost undriveable (will stall on any acceleration) until the regulator warms up, and may then be just fine. The best diagram for the vacuum connections is attached to the inside of your engine cover. The label is PN 105241, and shows up in the Workshop Manual on page D:08:01 as figure 44.
Consistently poor (lean) operation is more serious.
Cleaning the regulator is the only repair that is available to the shop mechanic. Remove the two banjo fittings (they are two different sizes so they cannot be put together incorrectly). Clean or remove the filter screens at the inlets to the regulator. If the screens are plugged it will cause very lean engine operation. This is also a good indication that there will be other fuel system issues, as there are similar screens in the fuel distributor and fuel injectors.
Any other problems must be addressed by changing the unit. This unit, like the fuel distributor, is sent in to DeLorean Motor Company and core-exchanged for a rebuilt unit. DO NOT take apart the unit as this may make the core unusable.
The electric plug is for a heating element that shortens the warm-up period for better warm-up emissions. That is its only function.
Revised DAS 6/22/2016 [edits and elaborations, added photo]