Hi everyone! Just wanted to share my experiences running e85 so far.
I got a quantum ethanol compatible fuel pump and hacked up my fuel cage to bypass the internal regulator, running an external FPR that sits in the engine bay (supported by the stiffness of the hoses). I reused the stock feed line and ran a hose back as a return, and drilled out the top of the fuel cage for the bulkhead fitting. Seemed to work okay, and haven't had any fuel delivery problems yet.
I'm using a zeitronix ECA ran into the ECT2 input of the ECU, which isn't quite the best choice because there's an internal pullup resistor on the signal and the ECA output can quite drive the signal all the way to ground. It works out okay because the minimum it can successfully output to the ECU is ~15% ethanol, which ends up being a small difference in fueling compared to E10 which is within acceptable margins considering weather and etc.
I obviously needed to re-tune the base gasoline fueling to account for the FPR, which i have hooked up to the intake manifold (running KW SC).
I've been running E73 since January of this year and so far haven't had fuel sender issues. Highway mileage is comparable to gasoline, but city mileage...oof, it's like driving a freakin suburban.
No issues with the fuel sender unit yet despite not touching it at all. I am either lucky or just haven't waited long enough. I ended up with some small fuel tank vapor leak DCTs at first which never caused a CEL (but always got told to check my fuel cap). I assumed this was due to the nature of the external FPR which isn't designed to hold pressure without a pump running. Lately though I have been getting gross tank vapor leak CELs and I have yet to investigate. Possibly the nut holding the return fitting has gotten loose with time (it has seen some track time) or possibly some of the OEM components for the evap system are dying. Hopefully it is just the dang bulkhead fitting nut and I can fix it by trying harder. Anyone else have EVAP issues yet?
Last edited by ravotex; 04-18-2019 at 10:24 AM.