Accel enrichment

[Dave Williams]

-> Why is accel enirchment (== throttle pump) needed?

 Theoretically (1) the air column responds faster than the fuel system,
so you would go lean on sudden acceleration.  The accelerator pump
temporarily richens the mixture to cover the lean spot.

 Theoretically (2) max power is to the rich side of stoich; the extra
fuel lets you make more power for acceleration.

 In practice it doesn't seem to matter all that much.  Millions of
British cars used SU side drafts with no accelerator pumps, most
motorcycles have no pumps, and I've disconnected the accelerator pump on
various carburetors with no noticeable change in driveability.

 Most EFI systems program an enrichment curve in anyway, but given an
EFI would have much less lag than a carb to begin with, I tend to think
it's mostly for a warm fuzzy feeling.

==dave.williams at chaos.lrk.ar.us======================================
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