Blow wiper fuse when car runs?

[Geo's66]

guys- working out problems on new restoration.. 78 Monte, replaced wiper motor, new electrical system, new switch, wipers worked fine when car was off, but key was on for accessories. Start car this am for a second, run wipers for the dew, wipers go up 1/2 way, stop!!!.... Blew fuse (15 amp)... Why would fuse blow when car is running vs wipers worked when engine wasn't running???

 

[fleming442]

Up the fuse to a 20, see what happens. If it's an all new build, check for pinched wires.

 

[Geo's66]

Ok, will try that- thanks

 

[Geo's66]

Although why would they work when engine isn't running, ran fine, but then when engine was on, failed?

 

[fleming442]

Not to state the obvious, but the circuit is overloaded. Did you do something like pull power for the HEI from the circuit? Also could be an insufficient ground (engine pulls the ground from the wiper motor while running). IIRC, there should be a little strap on one of the wiper mount screws that bypasses the rubber isolators to provide ground. Is that present?