hi guys!

My friend's '91 W126 500SE FPR vac has no connection. (maybe this is why the engine drank so much fuel than it should be). To where to connect the vacuum side of the FPR? Can I get the source vacuum from the door locks? (the gray plastic one in the 2nd photo).BTW, the plastic yellow vacuum line is from FPR.

photos:

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PINOY PRIDE

the fuel pressure regulator vac line is only a drip line if the regulator fails it goes into the little spot on the air cleaner breather hose

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1962 220S
1966 200 Diesel
1981 300TD Wagon
1984 500SL
1989 560SEC Euro

i find it odd that the 91 has the green 2 sleve connector temp sensor for the cis where my 89 560 euro has the 3 pin black top

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1962 220S
1966 200 Diesel
1981 300TD Wagon
1984 500SL
1989 560SEC Euro

I'll move this from Vintage to general Tech Help for a better viewing audience Sorry I don't know your answer!

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Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

Necro has it right, not a vacuum connection, just a failsafe in case of diaphram rupture.

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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

Ok, then, what controls the fuel pressure? as you see the photo, the reddish color surrounding the FD is the fuel but the FD is fine though, still puzzled by high fuel consumption, I suspect OVP, maybe busted? or fuel pump relay?

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PINOY PRIDE

I'm sorry Tom, I thought this is general tech. wrong room

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PINOY PRIDE

The regulator controls the fuel pressure and doesn't use a manifold vacuum reference to do so. Remember this is CIS not EFI. The regulator sets system pressure but the ECU is in charge of control pressure.

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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