My boss and I were discussing fuel injection a few minutes ago, and I was curious as to how mechanical fuel injection works.
I understand that there are probably a lot of different types of mechanical fuel injection (or maybe not) but I'm just trying to figure out how you run fuel injection without any sort of ECU.

I'm guessing a vaccum box perhaps?

I'm honestly clueless.

 

I had a '74 BMW with mechanical FI. It had an injection pump that worked kinda like a diesel injection pump. It was driven with a little timing belt that had to be synchronized with the crank, because the injection was sequential & multipoint. There was a lever on the side of the pump, connected to the throttle, so with closed throttle it injected a small amount of gas. As you opened the throttle it would inject more & more gas. You had some mechanical linkages & cams to adjust your mixture. There was no ECU of any kind.

The earliest Bosch CIS was mostly mechanical, too. The airflow meter was kinda like a big flap in the air stream. More air flow moved that flap, which opened some tiny needle valves, which increased the injected volume. That system was multipoint, but the gas was sprayed continuously, not pulsed. (CIS = continuous injection system)

 

I don't know how it works,but try Hillborns web site thats what oldtimers used and it's still used in some circle track apps.