Quote:
Originally Posted by NPT57
... [1] I have a good feeling the P1429 code is related to a fuse/wiring issues. I’ll have to track down
what fuse controls it as well as trace the wiring...
[2] The tank pressure builds while driving. When I open the gas cap, it seems to vent atmospherically from the neck out
of the tank.
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1) See attached ISTA ScreenPrints, showing the DMTL wiring & Connectors between DMTL & DME. My SWAG is that you
have an issue in the Black Red wire between X1714/2 & X6041/2, OR in the White/Black wire between X6041/2 &
X60002/17 at the DME. Since ALL THREE (3) DMTL components use same fuse (F06 in E-box), and you ONLY have ONE
Fault Code (for Heater), Lack of Voltage Supply is Unlikely. There SHOULD be Battery Voltage at X1714/4 (Red/White wire)
with KL87 active: Ignition ON & DME Main Relay (KL87) active.
WHATEVER is causing "Heater" activation to fail, that is NOT related to your PRIMARY issue of lack of tank venting during Fill.
2) I can't think of any reason that PRESSURE should INCREASE in tank when engine is running. The fuel pump is
pumping fuel OUT of tank, and if there were NO vent to allow air INTO tank, a VACUUM (less pressure than ambient)
would result. If you wrap Plastic/Saran wrap around cap and remove it, that should indicate if tank pressure is MORE,
or Less, than Ambient.
The Charcoal Canister is intended to absorb fuel Vapor after engine shutdown, to LESSEN Fuel Vapor escaping into
atmosphere after engine shutdown (Evaporative Emissions). If a vehicle is parked OUTSIDE in Warm Sunlight,
the Fuel Warms, and "Vapor Pressure" (Fuel Vapor) above the liguid Fuel increases with temperature, resulting in
"Evaporative Emissions" if NOT trapped in charcoal medium.
Cap "Whoosh" has NOTHING to do with Venting while Filling. Note that Vent line is BENEATH the Fill Cap. The Cap
is NOT Vented. Pump Shutoff while attempting to Fill Tank is due to some obstruction in the Vent line between
"14" & "16" in the diagram.
George