Since I am looking to build a street/track car without using a ecu my idea is use a air speed sensor and voltage regulator for the fuel pump and the pressure regulator on the return line would be on the fuel rail just above the injectors and controlled with the time in advance from ignition
It will sure help the rest of us if we knew what engine you are talking about here - and why you want to do this the hard way.
If it is an old school American V8 then intake manifolds and carburetors are readily available.
If it is an in-line 4-cylinder then some enterprising people have adapted motorcycle carburetors to them.
If you want fuel injection then question 1: what's wrong with the vehicle's stock ECU? question 2: MoTeC, Magnetti-Marelli, Megasquirt/Microsquirt, etc.
Yes, this stuff costs money.
Re-inventing a wheel that has already been invented long ago, costs more.
Half-arse-ing it because you don't/can't/refuse to do it the right way, is a sunk cost when it doesn't work right and you end up having to do it again, the right way.
It would help if you research and understand the mechanical injection systems from the past. Hilborn, Enderle, Bosch Kugelfischer, Lucas, Bosch CIS. The last is the only one of these that can provide accurate fuel metering and maintain that over the life of a road car.
No such thing as a mechanical ECU, as it would be an MCU.
Look into how the old Rochester Fuel Injection system worked, or the old Mercedes Jerk pump system, those are good examples of a mechanical fuel system..
Bosch K-Jetronic CIS was on millions of cars back in the day, and it worked okay enough to give cold start, high altitude, idle, low speed, full load, etc. Still, its day has passed. The fuel distributor was a very intricate instrument.
I don't know how the Rochester mechanical system compared to K-Jetronic.
