When I remove the fuel cap on my 88 300 E w124 I get a very large rush of air from the tank. It seems like an excessive amount of air to be normal. I know the caps on these cars are not vented,but the air must go somewhere.
Also It builds pressure on short or long trips.
Can this be causing my poor idle,and long cranking on start problems?

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88 W124 3.0
96 R129 119eng
06 ML350
98 ML320 sold
02 CLK55 amg

This doc outlines the ventilation system for the fuel. up to 50 mbar is apparently ok. more than that and we need to either clean or replace the vent, or reroute the vent tube.

Attached Files

Fuel Tank Ventilation System.pdf (188.6 KB, 555 views)

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77' 300D, "Cartman" SOLD @ 150K (didn't know what I had)
83' 300SD, "The Superdon" 325k+ @ 28mpg
95 E320 wagon, "Millennium Falcon" 231k+ @ 24 Mpg
95 E300D, "Sherley" 308k @ 33.69 Mpg, currently anticipating a head
99 Suzuki Intruder "Trudy" @ 45 mpg

Thanx ,great info and diagrams. Now I know where that evap canister is.
I think my pressure in the tank is above 50 Mbar. The conversion chart shows 50mbar is equal to only .725psi I feel the pressure comming out of my tank is above 1 psi

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88 W124 3.0
96 R129 119eng
06 ML350
98 ML320 sold
02 CLK55 amg