'87 4kq: fuel pump noise

[Huw Powell]

>>When I first turn the ignition key, I get a whine from the fuel pump for maybe
>>a second or less, every time. 

> Perfectly normal.  The fuel pump relay has logic in it that closes the
> relay contacts when the ignition is on and where there are ignition pulses.

Which is a safety feature, of course.

> The initial ignition on state often causes the circuit to close the contact
> momentarily because the startup-state "looks" like a single ignition pulse.
> This has the beneficial side effect of pressurizing the system to make
> starting easier.  Note that this applies only to the 70s to 80s CIS and
> CIS-E non-turbo cars.

Wow, I always thought it was a "feature."  Turns out to be just a 
friendly "bug!"

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/