99 F250 7.3. Starter only makes a thump when i try to start,so i had batt's tested (GOOD),I had starter tested (BAD). So i replaced and tried again, truck started fine 3 times, Then it went back to just a thump,so i pulled starter (mabye i bought a defective one) had it bench tested (GOOD). Reinstalled and cleaned all terminals,same thing started 3-4 times, back to thump.batteries have 12.3 volts, solenoid under hood has batt voltage on one side,the other side has 11 volts during start, Samething to solenoid on starter seems to me it should work. But for some unknown reason it dosent. I"m probley doing something wrong or skipping something important but have NO idea what it could be.
Any help would be greatly appricated.