What are the fuel pressure readings I should get on a 1979 450sl with bosch K-jetronic fuel injector system;
-"Key on", and "running" (taken at the cold start fuel line)?
- Run control pressure on a cold motor and after warm up (taken
between the fuel dist. and the warm-up control valve) ?
My fix-it books only give the volume that the pump should supply and not the pressure. I had a bad pressure control valve, ordered a new one and got a LOT of adjustment spacers. Any help???
I have learned that adding a 2mm shim increases the pressure about 10psi. Is 63psi too low for a 79 450 sl with the fuel pump running and the motor off?
UPDATED EDIT:
I found a non-MB source for the K-tronic and was given the following info-
System normal operating pressure is aprox 5bar (75psi). This is the point the fuel distributor's primary pressure regulator returns fuel to the tank.
Control pressure (controled by the warm up regulaor) will be aprox 1.0 bar on a cold motor and will increase to aprox 3.5 bar as the motor warms up.

Anyone know if this is the same for my 450 sl???

Those are good numbers. Here's some more detail (from Alldata, 380SL)

COLD ENGINE PRESSURE TEST

Place valve on pressure gauge in open position.
Disconnect the electrical connector from the control pressure regulator.
Place the fuel supply circuit under pressure by bypassing the fuel pump relay.
Make sure that the cold engine control pressure ranges fall within the specifications shown. NOTE: If the control pressure regulator incorporates a barometric capsule (altitude corrector), take this into account when reading the test pressures. Temperatures given represent ambient air temp.

0°C (32°F) No Value Given

5°C (41°F) No Value Given

10°C (50°F) 1.2-1.6 bar (17-23 psi)

15°C (59°F) 1.4-1.8 bar (20-26 psi)

20°C (68°F) 1.6-2.0 bar (23-29 psi)

25°C (77°F) 1.8-2.2 bar (26-32 psi)

30°C (86°F) 2.0-2.4 bar (29-35 psi)

35°C (95°F) 2.2-2.6 bar (32-38 psi)

40°C (104°F) 2.4-2.8 bar (35-41 psi)

If the pressure tested is incorrect, retest with a new control pressure regulator.

WARM UP TEST

Connect the vehicle harness connector to the control pressure regulator.
Energize the fuel pump by bypassing the fuel pump relay; after 5 minutes, the control pressure should be 3.4-3.8 bar.
If these values are not obtained check the power at connector.
If there is current at the plug, replace the control pressure regulator.
If the rise in pressure occurs too rapidly, replace the control pressure regulator.
Shut off the fuel pump.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Chuck,
Thanks for the info. I'll give it a try and let you know how I do.

Thanks again for the help!!!