A valuable tip as it relates to fuel pressure.
In vintage Volkswagen engines, it's essential to pay attention when using aftermarket fuel pumps rather than the correct German Pierburg. Higher-than-optimal fuel pressure can lead to various issues with the engine's performance, and is a commonly known problem with aftermarket units.
One common problem arises when the float valve (also known as the needle valve) in the carburetor's top gets overwhelmed by the excessive pressure. This can result in hard starting and flooding, as gasoline forces its way into the carburetor bowl and overflows down the throat.
To avoid these problems, it is recommended to check and adjust the fuel pressure. The ideal fuel pressure for most vintage VW engines is around 2.5 - 3 PSI at 3400 RPMs, as specified in the official Bentley manual.
To measure the fuel pressure, you can install a fuel pressure gauge between the fuel pump and the carburetor and run the engine. If the pressure is found to be significantly higher than 2.8 PSI, you'll need to take steps to reduce by stacking extra top gaskets to avoid potential engine issues. I'll write about this more in the future.
By maintaining the correct fuel pressure, you can ensure your vintage VW engine runs as it was designed, keeping it healthy and reliable on the road.