75 Explorer 440 charging problems

[povertycoach]

Background
Charging has always been a issue with this coach, so I decided to put in a GM 10si internally regulated 3 wire alternator.  I have used them before in hotrods and they are cheap and easy to install.  Easy until I tried to put one in Creampuff.
Installing this alternator accomplishes several things.  It eliminates the finicky external Chrysler voltage regulator and the notoriously poor performing Chrysler alternator.  Also, unlike the MoPar components, the 10si is available at every auto parts store, and is usually $15-$20 dollars cheaper.  The 10si can also be modded to be quite an amp making monster as well.

10si 101
This is not a one wire alternator.  It has a bat + connection and 2 field wires.  One field wire is connected (in a GM vehicle) to the charge idiot light.  When the key is on, engine not running, the alternator acts as a ground, thus completing the idiot light circuit and the light comes on.  Once the engine is running and the alternator is charging, the light goes out, and this wire provides positive current back to the alternator to excite the alternator.
The other field wire is the "sense" wire.  It  is usually connected to main splices or power distribution points in the electrical system.  It senses the voltage in the system and tells the alternator when to turn on.  The bat+ wire is just the charging lead to the battery.

My plan
I decided to just bypass the VR and existing charge circuit altogether by just running a new 4ga. wire from the 10si bat+ directly to the positive battery terminal.  I also ran a new 6ga ground from the alternator case to the main chassis ground.  I ran the excite wire to the fuse panel and connected to the ignition circuit.  To simulate a charge idiot light, I installed a resistor and diode inline to prevent current from back-feeding from the alt preventing me from turning the engine off.  I ran the sense wire to the positive battery terminal.  What could be a better indicator of system voltage than the batteries...right??  The main battery connection to the dodge chassis is at the starter solenoid, so that remained unaffected.

The moment of truth
Everything was wired up in the form of jumpers to test the install...Multi-meters connected all over the place.  With battery voltage on a the  new battery at 12.72, I tried several times to start the engine, but it only cranked.  I disconnected the sense wire and the engine fired immediately. Scratching my head, I reconnected the sense wire to the battery while the engine was running.  I could hear the engine RPM drop slightly and watched in delight as the voltage rose to 14.35 volts.  But within 10 seconds the engine started to falter and died.  It has done this every time despite every diagnosis and remedy I have thought of...bad diodes in the alt, bad rectifier, bad ground, poor connection, low battery.

The next thing
I was going to try is to electrically isolate the engine, charging system and ignition from the chassis.  I am convinced something in the existing wiring is causing this problem.  So my next plan is to use a remote ignition switch, jump the solenoid wire and the ignition hot from it and directly cable the battery to a new starter solenoid and ground.

I would welcome any of your input on my electrical shenanigans.

Poverty

[povertycoach]

The healthy 14.65 volt charge of the new alternator was causing the electric fuel pump to over-speed and over-pressure which flooded the carburetor and caused the engine to die.  Unplugged the pump, truck runs like new and charges perfectly.