Depending on the car, many of the simpler fuel flow/mileage
sensors (which obviously integrate speedometer data) didn't measure fuel
flow directly, but rather inferred it from either mechanical or
electronic fuel delivery system sensors (Bosch K- and L- Jetronic, etc.)
In other words, "the airflow sensor plate is at position x, which if the
fuel pump is providing the correct pressure to the injector loop should
result in fuel flow y, so that's what we'll assume." (Or, in the
electronic systems, "I'm commanding pulse width p to the fuel injector
magnets, which assumeing the fuel pump etc..."
Here in the Colonies, there are a number of relatively cheap fuel
flow sensor systems designed for the marine market. Most of them use
typical "pinwheel occulting an LED" sensors made by the FlowScan
corporation. While you can sometimes find the sensors alone, the whole
systems are often so cheap (ca. $250) that it might be worthwhile to
install them "as is."
|