Your Receptacle is Wired Incorrectly
Top picture shows wires going into the white back section of the receptacleOriginal answer deleted - it was based on my erroneous assumption that this was all 14-50. The green ground and white neutral should be opposite each other, withIt turns out the redhouse connection (inlet and black hot wires on either sideone of the groundcord) is SS2-50 while the generator is 14-50. InsteadNot sure why, black and white are on either side of the groundbut that's what is being installed.
Interlock and breaker connections look OK. The junction box looks OK, though I can't tell foram not sure which way itwhy there is a junction box and not just a single cable run from panel to inlet.
Which leaves testing the extension cord and the receptacle wiring with a multimeter as the next steps. If the generator runs by itself should be(others already suggested checking that) then the remaining possibilities are:
- Ground in the current position
- Black and red next to ground
- White in the current red positionExtension cord - miswired or internal short
or
- White in the current greenInlet - miswired or internal short (ground) positionunlikely because OP tried two different inlets
- Black and red next to whiteJunction box - looks OK but some testing wouldn't hurt. And fix up the open cables outside the box.
- Green in the current red positionBreaker/panel - looks OK, but again testing wouldn't hurt.
but I'm willing to bet it is oneMost of those possibilities. Itthis testing should be pretty clear just by looking at the front and back ofdone using a multimeter to check resistance/continuity with the receptaclegenerator off for safety. AndIf/when you can always check for sure usingfind a multimeterproblem and resolve it, then put everything back together and try the generator again.