Converting to run E85 is relatively easy. Simply change the injectors to approximately 25% larger ones. Dump in the E85 and go.
If you want to get fancy you could recurve your distributor (if so equipped) for better power and mileage. Edit: Your '91 probably has computer controlled timing, so you'd be out of luck there unless you went with an aftermarket ignition and a duraspark distributor or something like that, or found another way to change timing.
It gets a whole lot more complicated if you also want the option of running gasoline.
Last edited by rusty70f100; 05-18-2007 at 11:57 AM.
You could always do some experimenting to see how much E85 your car can handle. Start with a 20%E85 80%Regular mix then work your way up till the car starts running crappy. Then back it down to where the car is comfortable with it. If you have a high compression engine it can handle more E85. Right now Im running a 50/50 mix in my 99 F-150 and 98 Stratus and it works ok but I lose about 20 miles per tank. Currently E85 is only 10% cheaper than regular gas (at least where I buy it from) so Im barely comming ahead with the price differance.