System Pressure

There are 2 versions of Fuel Pressure Gauge (100 589 00 21 00) available. One version has junction block with 2 valve handles which are numbered "1" or "3" in the following procedure. The hose exiting from the side of junction block by No. "1" valve handle is hose "1".
The second version of Fuel Pressure Gauge (100 589 00 21 00) has a single valve handle on junction block. Hose leaving junction block 180 degrees from valve handle is hose "B" and hose leaving junction block 180 degrees from line to gauge is hose "A". When testing system pressure using first version of fuel pressure gauge, close valve "1" and open valve "3". On second version, open its valve.
Remove plug from test port in lower chamber of fuel distributor. Connect fuel pressure gauge line "1" or "A" to test port in lower chamber of fuel distributor. Use M12 X 1.5/M8 X 1 Reducing Bushing (102 589 06 63 00) to facilitate connecting hose to chamber port.
Remove fuel supply line for cold start valve from top of fuel distributor. Attach pressure gauge line "3" or "B" to cold start fitting on fuel distributor upper chamber. System pressure is checked with engine off. Engine temperature has no effect upon system pressure test. Remove fuel pump relay from relay board (under hood on fuse panel). Bridge relay board terminals No. 7 and 8.
System pressure should be 76.9-79.8 psi (5.4-5.6 kg/cm² ). If not, check for defective fuel pump, restricted fuel return line or defective differential pressure regulator. Open pressure gauge valve "1". Remove bridge from fuel pump relay board.