Converting a 1994 volvo penta 7.4 to a 1 wire alt from a 5 wired

[llewis01]

I have a 5 wire alt on 1994 volvo penta 7.4 carb engine with electric choke. I going to a 140 amp 1 wire alt. I have the fuel pump connected to the oil sending unit. I have the purple wire going to the coil and the purple/white going the carb elect choke. One wire is going to the batteries(on a larger wire) and 1 wire going to ground. All the other wires I'm using. In the diagram that is attached. The circled one in blue is my old prestolite alt. Everything to work ok. It starts and cuts off and the fuel pumps cuts off. My 2 problems are that the choke pulls off to quick and after maybe 50 hrs of runtime I keep burning out the regulator. What could the problem be?

 

[Scott Danforth]

Is the alternator marine rated?

I wouldn't do a 1-wire in a boat. You discovered why.

You have to run a dedicated ground (second wire)

The choke is run off the ignition (purple wire). and having the sense hot-wired to the B terminal (as all 1-wire alternators do) kills the battery. Plus your fuel pump is driven off the alternator so without being properly rewired, the fuel pump drops out after cranking

 

[llewis01]

The fuel pump is wired correctly and works as it should. The choke works off the purple/white wire as shown in the diagram. Plenty of people have switched to a one wire system. I think it is some kind of feed back in the system but can't figure out way. If the regulator in the alt went out quickly I would the is a short but, after running for hours and then goes out I just put finger on the problem.

 

[Donald0039]

Why go to a single wire alternator? They are mainly for hot rods. You need #4 gauge wire, possibly #2 gauge depending on how far away the battery is from the alternator.

The problem with a single wire alternator is they don't always properly sense the battery due to load.

I would guess your regulator burning out is a bad ground problem. Or intermittent ground problem.

Maybe a ground strap.