You can run E50 (most of the time) without a HPFP. Very very rarely do some trucks have a hard time running e50.
E50 is a blend of E85 + pump 91oct/93oct. You need to know the "e85" content coming out of the tank (use something like this, https://www.fuel-it.com/ethanol-content-tester/) Once you know that then you can blend a certain amount of 91/93 into the e85
E50 is a blend of E85 + pump 91oct/93oct. You need to know the "e85" content coming out of the tank (use something like this, https://www.fuel-it.com/ethanol-content-tester/) Once you know that then you can blend a certain amount of 91/93 into the e85