I have a 75 with Fitech and a GM style one wire alt. I believe that i am having wiring issues that is causing my Fitech to act up.
Very possible. You may already have read some comments about just that issue with pretty much any brand or style of EFI conversion
The wire system on Broncos was ok when new, but add 42 years and things don't always work at their best. But you seem to have at least one problem that could be doing some mischief to your install.
Also, when a load is put on the engine in form of higher rpms or lights, the voltage drops.
That's not good, and means that your alternator is not putting out sufficient current to keep up. This is either due to a bad charge wire (it's the only wire, correct?) or a bad alternator. No matter how new it is.
I know the alt is good it is putting out 13.9 volts and is a brand new powermaster 100amp.
First, did you test your alternator? What about the charge wire? That 13.9 volts really is not high enough. Yes, it's "sufficient" but is also indicative of something not quite right because you should be reading more like 14.4 0 14.6 volts at the battery when the engine is running.
As said quite often here anymore, new does not mean good. Although Powermaster is a high-quality brand and makes good stuff generally, even theirs can fail.
But this is also an area where the chassis wiring can be part of the problem.
But let's talk about the details of the install. Did you create a new charge wire to go straight to the battery? Or are you running the original Black w/yellow wire from the old alternator?
The original wire is not good enough for this at best, and may also be deteriorating.
Is this a true 1-wire alternator, or does it have a 2-wire connector with a Red and White (or Brown) wires in addition to the charge wire? Sounds like it's connected and running or you'd never see that 13.9v, but it still needs more for one reason or another.
So I think I am going to go ahead rewire it. I may try to redo what is there. I may have jacked something up when converting to the single wire.
Definitely check into it. I'm not against re-wiring fully by any stretch, because that's the best way to upgrade your Bronco from an electrical standpoint. Everything just seems to work better with new wires and connections.
But let's check the basic stuff first just to get you up to a better snuff.
But what is the best kit to use with the single wire alt and no regulator.
They don't care what alternator you're running. The charging circuit of a 1-wire is obviously separate from the rest of the harness. The harness from American Autowire does not even include anything for the regulator and says to use a 1-wire. But even though the others have the provision for running a regular style of alternator, you don't need to use them.
What's the part number of your PowerMaster setup? Just wanted to check out the details.
Before making your decision, at least find out what's wrong with the alternator now. If it's the wiring, you can change it. But if it's the alternator it's better to find out now rather than putting all your time into a new harness only to have the alternator still not capable of supporting all the loads.
And that comes back to the FiTech. Any EFI is going to stumble with low voltage. Even your 13.9 is probably less than it wants to see under normal conditions. But as soon as you apply a load and the voltage drops, it hates it even more.
Good luck.
Paul