After replacing my fuel filter with the newer narrow mouth style, I attempted to prime the fuel pump using VCDS. I initially tried the 01-Engine->Basic Settings->Block 35->On procedure, running it three times for 60 seconds each. Despite hearing both fuel pumps activate, the filter remained dry, preventing the car from starting.
Next, I used the 01-Engine->Output Tests->Fuel Pump Relay Control Circuit and 01-Engine->Output Tests->Relay for Auxiliary Fuel Pump procedures. I ran each test multiple times, but the fuel filter still wasn’t filling properly.
Finally, I manually filled the fuel filter canister with diesel, which allowed the car to start.
My question is whether the incorrect VCDS procedure could have caused this issue. I believe I used “Selective Output Test” and manually alternated between the two pump tests instead of using “Sequential Output Test” as shown in some online guides.
Could using the wrong output test mode in VCDS prevent the fuel pump from priming correctly? Has anyone successfully primed the fuel pump using the Block 35 method? Should “Sequential Output Test” have been selected for this procedure? I’m concerned that this mistake might lead to future problems, specifically High Pressure Fuel Pump (HPFP) failure.
