1987 Trazer

[overtimeracing]

Hey guys, my son and I are building him an 87 trazer. We are having trouble with the charging system. We are using an older 350 with an internally regulated alternator. We are also using the stock wireing harness from the 87. This had the fuel injection, we just aren't using it. When we remove the alternaton and had it tested, it checked o.k. but when it is on the truck it won't charge. What am I missing?? Thanks... I'll get some pics on here asap. Thx...