I have a 1986 Ford E-350 motor home. When I turn the ignition on only sound is a brrrrr (for lack of a way to explain) I have seen this many times and has been a bad ground. I put in new positive and...
Sounds like maybe the starter motor is turning, but the solenoid is not kicking the starter gear out to engage the gears on the flex plate or flywheel. JMO