Came across this thread when looking at some C210 accident history.
I had an io550 conversion done on my 1980 C210 (in South Africa) and as far as I remember the fuel pump switch remained as a spring loaded rocker.
On another aircraft I had some interesting history with the same style of Fuel Pump.
I was ferrying a C206 from Joburg to Lusaka (same spring loaded rocker switch). The aircraft was straight out of some maintenance work. 50nm to go and the engine starts to wind down as if no fuel. Plenty in the tanks,so I switched to both tanks and pushed the rocker in. The engine picked up but only about 50% power. As soon as I released the rocker it starts to die. I was at about 7000ft agl. With the rocker held in I was able to keep the engine going but not maintain altitude, but it at least it gave me some extra minutes to try and select a forced landing site.
Bush was very thick and nothing was available so I just stalled it into the biggest tree I could find.
Got down with one broken wing and very bent airframe, but no fire. 3 pax were ok.
My Injuries were serious due to the fact I had to hold the stick with my left hand and leaning forward had my right arm across my chest to hold the fuel switch in position. Thus I only had my lap strap on and no chest strap. My face left an imprint on the control panel!
But the main point of interest was that the fuel failure was caused by maintenance not tightening the nuts on the fuel spider which sat on top of the cylinder block. Hence when they worked loose after 4/5 hours the fuel was spraying out instead of going into the cylinders. By activating the booster pump I was spraying a strong jet of fuel for several minutes onto a very hot set of cylinders. By rights I should have exploded in a fireball long before I reached the ground!
Another nugget of experience and I managed another 15 years of exciting bush flying.
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