1981 911 CIS fuel system pressures

[gregguillaume]

I followed the procedures to test the fuel system pressures and got the following results. Can someone tell me if they are in spec? The residual pressure bled off quite quickly. Is that normal?

Car: 1981 911 US 3.0L CIS
Ambient temp 60F
WUR resistance cold: 26 ohms, warm (after the test below): 9 ohms

Pressures below were taken between the Fuel distributor and the Warm-up Regulator
System pressure 65 lbs, 4.5 bar
Cold control pressure 25 lbs, 1.7 bar
Warm-up
0 sec - 25 lbs, 1.7 bar
30 sec - 30 lbs, 2.0 bar
60 sec 35 lbs, 2.4 bar
90 sec 40 lbs, 2.7 bar
120 sec 45 lbs, 3.0 bar
150 sec 50 lbs, 3.4 bar
180 sec 52 lbs, 3.5 bar (max pressure reached)

Pump then turned off
Residual pressures
Immediate drop to 20 lbs, 1.5 bar
30 sec, 15 lbs, 1 bar
40 sec, 0 lbs - some bubbling noises from the fuel accumulator, possibly.

Thanks for the help.

Greg

[RarlyL8]

Your fuel system should hold pressure after cutting the engine off. Typical culprits are the fuel accumulator and/or fuel pump check valve.