Nofly:
It is not about the hardware. That's the easy part. There's probably 100s of existing fuel systems that could be adapted. Matter of fact, you can legally pull the entire fuel-injected engine from a car and put it in an aircraft-- so long as you certificated it under Experimental. (FAA wise)
The problem is when you want to install it on a Type Certificated aircraft, or more precisely a Type Certificated engine. That's where the money comes in.
Even if you use an existing fuel system, the entire system must be de-constructed to comply with the requirements of FAA certification.
This is just the surface:
http://www.faa.gov/documentLibrary/m...4C-CHG_1-5.pdf
Now if the TC holder is not interested in development, your only option would be obtaining a Supplemental TC. The kicker is you would have to do this (i.e., pay for) for each TC model you wish to install your system. This includes a bunch of engineering approvals, test beds, prototypes, etc.
I think it can be a little ridiculous as there is some neat stuff out there that could very easily be adapted and provide safe flight. But it's the regulatory system we have.
My personal favorite: EC135 helicopter transmission requires a "very special" oil as part of a modification. When you open the fancy box it contains a Castrol oil for Mercedes Benz transmissions. The only difference is a small sticker that says "ZF approved" with an additional cost of $25 a quart because it is "certified oil."
W1