Fuel Pressure - Porsche 944 Workshop Manual

944 S/944 S2
Test Point 18: Fuel Pressure
Fuel collection pipe has a test
connection at left front. Unscrew
cap nut of the test connection.
Important! Inserted ball seal could
fall out!
Connect P 378 pressure tester on
the test connection. Start the
engine. Vacuum on pressure
regulator at idle speed:
Test pressure: 3.3 +- 0.2. bar
Build up pressure again by switching on the fuel pump briefly. Remove return pipe on the
pressure regulator (fuel pump must not be switched on).
DME - Diagnosing/Troubleshooting
Printed In Germany - XXI, 1989
Fuel System - Electronic Control
Hot starting problems:
Check with the engine stopped and fuel pump
running, without vacuum on the pressure regulator
(this requires removing the DME relay and bridging
terminals 87b and 30):
Test pressure: 3.8 +- 0.2 bar
- Stop fuel pump. Read pressure on the pres
sure tester (specitication: 3.8 +- 0.2 bar).
- Max. permissible pressure drop on warm
engine: 0.5 bar in 30 minutes.
- It the pressure drops below the specitied
value, proceed as described below.
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