If it is a Mini Starter Type of starter, I'd suspect the solenoid is bad...
FIRST, try rotating the engine BACKWARD about 1/4 turn, the Starter drive MAY be stuck, this will free it.
NEXT, To test, REMOVE the yellow wire, Jump (as you did before) The Small terminal, to the large Bolt (Battery Cable) Terminal, THIS WILL SPARK! The solenoid draws a lot of current, but should energize the starter if the solenoid is working. If it doesn't in a fraction of a second, and sparks like you shorted across the battery, STOP. If it won't turn over, the solenoid is bad or the plunger is jammed inside the solenoid.
NEXT, get out your DVOM, Set it for V X 50 or autorange, Measure the Yellow wire, With the KEY in run, It should read "000", Then have someone hit the key to start, It should read 12 Volts (or whatever your battery static is reading.) If it does your solenoid circuit is correct. If it has 12 volts in run, OR "000" in Start, it is shorted, or mis~wired, you'll need to check the wire to the neutral safety switch then to the ignition switch for shorts or opens.
AS FOR THE PUMP...
A Lot of Fuel pumps will pump up to pressure and STOP..until the pressure is relaxed, To check, Open your fuel line or Filter and drain the line..then connect it back up, and turn the key on, It should "Hammer" until the line fills again, then shut off..If so, It's doing it's job..
IF NOT, Check the Tank ground at the pump, be sure it is hooked up..and you have 12 volts to the power side of the pump. If you do have that..the pump is dead..(or internally clogged)..removel will be necessary. If you have NO Power at the pump, Check for a bad Pump relay (not sure Porsche runs them or not) And / Or a blown Fuel Pump fuse.
The AMP Gauge is a simple device that has the Current from the vehicle run through it (or it's remote shunt) If it is open, (depending upon how configured,) The car will Have no power to the electrical system. Since you say movement is there, but slight, it may be damaged by a high output alternator, where a low Current alternator came out..(GM Vs Porsche charging systems) You may have to replace it...OR better yet , and much safer and easier to install, put in a Volt meter.
Hope it helps!
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