1986 911 Turbo - black/red relays

[tasturbo86]

Fooling with a no spark problem.
I lost track of where the red and black relays go on the main fuse panel.
Anybody got a picture?

[RarlyL8]

[tasturbo86]

Just for the two fuel pumps?
Hmmm, mine must have multiplied

Thanks!

[dap930]

The red relays have a flyback diode installed across the relay coil to prevent a voltage spike when the coil is de-energized.

[mark houghton]

Originally Posted by dap930

The red relays have a flyback diode installed across the relay coil to prevent a voltage spike when the coil is de-energized.

In other words, counter EMF as the magnetic field around the coil collapses and induces a voltage spike, which in turn can arc across the relay points and shorten their life. The spike still happens, but can't get past the diode. Layman's terms for what very little I know about electricity.

Or am I confusing this with capacitors in old-style points ignition where a person had to set the gap and thus the dwell? Showing my age and fuzzy memory once again, so never mind!