Just to put in some more confusion:
There are eight fuel Pumps in a Bf110 C.
Two pumps per engine, which are engine-mounted and driven by the engine itself. These two pumps are operated by two units 'Brandhahn Armatur' which have three purposes: first to filter fuel from any polluntant, second they work as a deshydrator, third they operate as a fuel cock. These units are fuel-cock-wise operated by the two red-knobbed levers on the left of the pilot. The lever either closes both units (Brandhahn zu), opens unit one P1 (pump 1 can deliver fuel) unit 2 or both.
Brandhahnarmatur is 'A' in following picture
'B' is fuel line connector to engine driven fuel pump
So thats only 4 pumps, right!
The Bf110 has 4 fuel tanks, 2 in each wing. The forward tanks are maintanks which can feed the engines. The rear tanks are reserve tanks. To use the reserve tanks you have to use fuel out of the main tank first and then feed fuel to the main tank out of the reserve tank. (remember engines only can be fed from a main fuel tank!)
Even if one main tank is damaged both motors can be fed by one main tank. To this every fuel tank is equipped with one immersion fuel pump for transfer pumping purposes. The direction of transfer pumping is controlled by the two lever switch to the right of the pilot.
C4 and C7 switching logic should be:
°|°
°|° normal switching for use of main tanks, left engines fueled by left main tank and right engines out of right main tank.
°\°
°/° transfer from reserve tanks to left main tank
°/°
°/° transfer from reserve tanks to right main tank
°\°
°|° fueling both engines from left main tank, i.e. if right main tank is damaged
°/°
°|° fueling both engines from right main tank, i.e. if left main tank is damaged
Whether that is correctly simulated, we have to find out.
http://forum.1cpublishing.eu/showthread.php?t=27050