Operation CHARM: Car repair manuals for everyone.

Fuel System Pressure Test


Test Values
^ Primary pressure - 5.0-5.6 bar (76-82 psi)
^ Control pressure, warm-up cycle completed - 3.4-3.8 bar (49-55 psi)
^ Acceleration enrichment with 500 mbar (15 in. Hg.) vacuum applied to lower connection of warm-up compensator with engine warm - 1.4-1.8 bar (20-26 psi)

- Control pressure, engine cold according to ambient temperature
warm-up compensator. Refer to charts below.

Temperature/Pressure Chart:




^ Chart for warm up compensator with Bosch part number ending in 068.

Temperature/Pressure Chart:




^ Chart for warm up compensator with Bosch part number ending in 155.

Special Tools

Pressure gauge - PN 102 589 002 100:





Clamp for hose lines - PN 000 589 403 700:





Vacuum tester 0-1000 mbar - PN 116 589 252 100:





Hand vacuum pump - PN 001 589 732 100:





Self Made Tools

Contact bridge:




- Use 12 AWG electrical wire
- Two single pole plugs - Part No. 004 545 84 88

Conventional Tools
^ Digital multimeter (volt-ohmmeter) - e.g. Sun Electric DMM-5

Pressure gauge, first version:




^ Connection 1 = hose to fuel distributor
^ Connection 2 = hose to pressure gauge
^ Connection 3 = hose to disconnected control
pressure line

Pressure gauge, second version:




^ Connection A = hose to fuel distributor
^ Connection B = hose to disconnected control
pressure line

Test Conditions:
Ignition system must be in good working order, idle speed, and ignition timing must be set to specification.

r�L���ШTest Procedure:







Fig. 1:





Fig. 2:





Fig. 1:





Fig. 4:





Fig. 5:




^ Fig.5 - 37 = Thermo-vacuum valve 50°C (122°F), red or 70°C (158°F), yellow