I've been having an issue on a local Evo 10 with some fuel delivery problems on E85 that we had kept chasing and couldn't quite get...
1. Fuel Relay OK
2. Upgraded Injectors
3. FuelLab AFPR (raised pressure no change)
4. Walboro in-tank pump...
This, as far as I know, was the first Evo 10 tuned on E85 in America. We tuned this back in March, on the stock turbo (it now has a Blouch Dominator 2) so it most likely has the most miles on E85 of any other, you can see the results here: http://forums.evolutionm.net/7044333-post55.html
Today it came back in after upgrading the underhood fuel lines, adding a upgraded fuel rail and a FuelLab AFPR. Still same issues.
I finally decided to take the pump out and check things out. Here is what I found:
Notice the orange Ultimate Racing Supplied slinky fuel line. Guess what color they are in regular gasoline and stock? Semi-translucent white, like this:
The line was also sticky to the touch which I imagine is because it has been breaking down in the E85. The black slinky line was as well. (disregard the loose pump)
The fuel pump sock used was also the "walbro" kit cotton based sock which had all the cotton broken down and missing, which is probably now in the fuel pump and filter.
We will be replacing the slinky OEM line (which is pretty ghetto to begin with) with real fuel hose.
I *HIGHLY* recommend all Evo 10 E85 users to replace these lines with real fuel hose and do not use the cotton based fuel sock, but a Evo 8/9 OEM sock or some other non-cotton based one.