Can anyone help here - I checked my fuel pressures today on my '91 300CE with the M104 motor and I get 3.4 bar with ignition on and car not running and 6.4 bar with car idling. Raising the rpm's does not change the fuel pressures at all...while idling, if I close off the ball valve on my gauges to the top chamber of the FD, pressure drops to 6.0 bar.

The only specs I can find are from FSM 07.3-0121 and they are for a M103 engine, and I'm not sure what they mean...sounds like 5.5 bar at idle...

I read a post by MBDoc indicating that it should be 3.5 bar at idle???

Thanks,
ryan

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RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE

3.5 bar is the spec for EFI, you have CIS which should operate at the higher pressures.

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90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
Milled & ported head, 10.3:1 compression
197° intake cam w/20° advancer
Tuned CIS ECU
4° ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff