Itinerant Air-Cooled

All my life (or maybe just since 1990 or so) I was under the impression that it was pointless at best, damaging at worst to press the accelerator pedal at all before or during the starting of any f.i. engine. But owners manuals for the 1972 Type 3 says to always keep it fully depressed before and during starting.

How and why was I misled?

whc03grady wrote:All my life (or maybe just since 1990 or so) I was under the impression that it was pointless at best, damaging at worst to press the accelerator pedal at all before or during the starting of any f.i. engine. But owners manuals for the 1972 Type 3 says to always keep it fully depressed before and during starting.

How and why was I misled?

There are different fuel injection systems working under different principles and environmental conditions.

When you are fully apprised of the physics of how all of this stuff works, the owner's manuals and principles and conditions are actually in concordance.

The 1968 Type 3 owner's manual instructs to never touch the accelerator.
By 1972, Volkswagen had discovered that you get more reliable starts by adding air (fully depressed accelerator) AND a rich fuel signal for cold starts from the manifold sensor.

This was true for 411s equipped with D-Jet as well.

L-Jet equipped engines on all VWs kept the recommendation not to touch the accelerator when starting.

BUT we in the world have discovered a few techniques over time.

In extreme cold, a quick depress of the accelerator on L-Jet engines can offer a little shot of additional fuel, but as importantly, it offers AIR which many engines need more of. Carbureted and fuel injected engines that have not started the first time, can benefit from flooring the accelerator during cranking to air the engine out. *You* have to make the call, however, as to whether the engine has not started because of too little fuel, or too much. Your dual-carb bus has an almost fail-safe starting procedure if it hasn't lit-off immediately like the Road Warrior did for thirty six years. Pump the accelerator two or three times then hold to the floor while cranking. It will go from rich towards lean and it will find the happy place.
Colin

Amskeptic wrote: In extreme cold, a quick depress of the accelerator on L-Jet engines can offer a little shot of additional fuel,

Dear L-Jet guru: Can you please elaborate on how, exactly, this happens? There's no accelerator pump...

SlowLane wrote:

Amskeptic wrote: In extreme cold, a quick depress of the accelerator on L-Jet engines can offer a little shot of additional fuel,

Dear L-Jet guru: Can you please elaborate on how, exactly, this happens? There's no accelerator pump...

Opening the throttle plate during cranking moves the wiper towards richer a little, unless your valve guides or Raby cam have killed all idle airflow. Additionally, cold start fuel spray gets lofted into the intake runners more successfully when the throttle plate is fully open.
ColinGuruMyA$$