'87 4kq: fuel pump noise

[Ti Kan]

Andrew Buc writes:
> When I first turn the ignition key, I get a whine from the fuel pump for maybe
> a second or less, every time. I just took the car to Al Swackhammer for some
> work, and he pointed this out, but I suspect it's been doing it for a while and
> I wasn't noticing it.

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.
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.

-Ti
2003 A4 1.8T multitronic
2001 S4 biturbo 6-sp
1984 5000S turbo
1980 4000 2.0 5-sp
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