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#1
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W124 M103 fuel pressure regulator leaking?
I'm seeing fuel in the clear vent tube, been that way for ages, always ran fine, just turned 100K miles. Is it normal or does it mean a diaphragm leak?
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1988 300E Last edited by tilac1; 06-15-2015 at 01:37 PM. Reason: more info |
#2
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Are you looking at a device under the hood or under the car near the fuel pump?
The pressure reg is under the hood , fuel accumulator under car. The pressure reg should have a vacuum line , fuel return. Accumulator has fuel in / out then a vent hose that leads to the suction side of the fuel pump. This was done so if the diaphragm tears, fuel circulates back to the tank rather than being dumped on the ground / hot exhaust like some cars. |
#3
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Not the accumulator. The FPR has a clear vent tube connected to the valve cover. Sometimes I see a bubble of fuel in the line.
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1988 300E |
#4
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Typically, if you see fuel in the line, that means that the diaphragm within the regulator has broken down and the reg should be replaced. Notice where the clear line leads to... the breather hose from the valve cover to the air cleaner. Fuel isn't supposed to be in that system. Too much fuel and you'll have idle issues or have a hot mess on your hands. It's a relatively cheap and easy fix to replace it with even a used one. Lots on ebay to find.
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03 CLK430 Cabrio 211K Pweter Silver/ Oyster Leather 90 300SEL 214k Pearl Black/ Alto Grey/Black Leather Prior: 85 190E, 88 300TE, 89 300TE, 90 300E 2.6, 90 300TE, 92 300E 2.6, 91 and 93 300SL, 87 Ferrari Mondial Cabrio |
#5
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Break and undo all the fuel connections before you loosen the mounting bracket bolt.
Easiest way I found for the replacement is to reattach the smaller connection first, the fuel distributor line second and then the last one. THEN bolt down the mounting bracket.
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1985 300D 198K sold 1982 300D 202K 1989 300E 125K 1992 940T "If you dont have time to do it safely, you dont have time to do it" "The democracy will cease to exist when you take away from those who are willing to work and give to those who would not." |
#6
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Bosch FPRs are over $200 and I don't want to replace it if seeing a fuel bubble is a normal occurrence. It's been like this for a long time but seemingly runs fine.
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1988 300E |
#7
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Since the FPR vent/leak line is connected to crankcase ventilation components, the liquid that is observed in the line is most likely condensed water vapor, not fuel.
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#8
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Good idea. I'll check and see if it's gas or not.
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1988 300E |
#9
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$6 at pik a part
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1985 300D 198K sold 1982 300D 202K 1989 300E 125K 1992 940T "If you dont have time to do it safely, you dont have time to do it" "The democracy will cease to exist when you take away from those who are willing to work and give to those who would not." |
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