Engine will not crank over?

Interesting observation about it flooding during the summer. That would suggest a leaking injector, not a leaking regulator.

Every time you turn on the ignition switch, a priming pulse of fuel enters the intake manifold. That extra fuel can be the cause of flooding. It probably doesn't happen in winter because very little of the raw fuel vaporizes and enters the engine. Most of the fuel just puddles in the intake manifold rather than drenching the spark plugs.

Caradiodoc

Leaking o-rings will bleed off fuel pressure, but you'll smell it and it would be a severe fire hazard. More likely the pintle valve isn't sealing, dribling fuel into the engine. Your mechanic will remove the 4 or 6 injectors attached to the fuel rail, flip it over, then watch to see which ones are wet on their tips. Only the leaking injectors need to be changed, but the better shops will try to get you to replace the entire set because they are matched for flow rate. GM has a lot of performance problems due to not spending the few extra bucks to match injectors on the assembly line. Chrysler has very little trouble with injectors.

Injectors are kind of expensive, so you might want to consider doing nothing. This isn't a serious problem. In my case, I consider it to be a very minor inconvenience. It's been doing this for over ten years. It hasn't gotten any worse and I doubt it will get worse in the future.

You can test for a leaking regulator yourself. Fuel that goes through it goes right back into the tank. Use a special plastic hose pinch-off pliers to pinch the return hose when you know the car will be sitting for a few days. Remove the pliers just before you start the engine. If it solves the problem, suspect the valve in the regulator or the o-ring around the stem is leaking. This too is not a serious problem.

Caradiodoc

There's no fuse in the starter circuit so disconnecting it isn't going to affect anything. That starter draws up to 150 amps.

Plug in a pair of spade terminals in place of the fuse, then connect a pair of jumper wires to them and to a 12 volt light bulb. When the circuit is turned on and the short is present, the bulb will be full brightness so be sure it's not resting against a plastic door panel or on the carpet. Now you can unplug things and move wire harnesses around to see what makes the short go away. When it does, the bulb will get dim or go out. In particular, check for the wires to the oxygen sensors to see if they fell down onto hot exhaust parts.