1/3 of the way down is not "just into the discharge side", it's discharging .... if it's not charging after a period of working properly, it's not the gauges fault, it's something in the gen/reg overheating although they work the first 15 minutes, that kind of problem won't show up on a normal bench test ... change the gauge and prove it to yourself, then try another generator and/or regulator - or have your guy run the current ones on his bench tester under load for 15-20 minutes .... also, running only the spark plugs shouldn't be drawing enough current to show 1/3 discharge, once it starts showing discharge, shut it off and starting at the battery with a meter, see if there's a current draw someplace that only happens when it's hot
and how do you "hand start" the truck, use a crank?
Bill
