It looks like most people here mount their Flex Fuel sensors near the fuel rail - logic being that ethanol content can change by the time it goes from pump to fuel rail on an returnless system.

I however have an NA which is of course a return style system. I am thinking of mounting the sensor near the fuel pump location as opposed to in the engine bay - is this not a good idea? I haven't seen anyone mount it like that yet, so wondering if I should just go for the way everyone else does it.

 

Mount anywhere between pump and rail, but only on feed side not return
Most people mount in bay for easier wiring and plumbing

 

Really? I always thought it was only on the return side, not the feed. Blockage in the sensor results in a rich condition as opposed to lean.

mine is in the passenger side rear fenderwell area by the fuel filter.

 

when we tuned psyber's car he had it on return and e content readings would drop pretty significantly during a pull. moved to feed and problem solved

 

Your fuel should stabilize by the time your car primes and runs within the first 30 seconds of you have a return system.... Unless you have an alternate tank your hard switching from.

As Vlad said, save yourself headaches and put in on the supply line. On mine it would drop ~20% at full tilt and do all sorts of weird things with map interpolation.

 

Thanks everyone! I'll be mounting in the gas tank area on the supply line.

 

I put mine on the "frame rail" where it turns upwards to the rear of the car.