Lights on no start

[BurninRubber]

I turn the key on and the light is on. But when I turn the key to start it the power goes out till I turn the key back to the on possition. But if I disconnect the battery then it will start. The battery, starter and alternator have been tested. I even checked the relays.

 

[corvairbob]

i had the same thing a year ago and they said the battery was good and the starter checked out good. turned out to be the starter. the contacts inside the solenoid were corroded. i would up junking out a good battery because the second opinion said a bad battery because it seemed the battery was low but it was always the starter. i got a junkyard unit and it has ran good since. i took the old one apart and found the contacts and electrical corroded.