Backward battery now gauges dead?

[AlphaJustin]

The previous owner (I swear it wasn't me) put one battery in right and the other in wrong then both in wrong engine still cranked over so I bought it. Now I've got the batteries and wires i could see melted corrected. The fuel gauge is pegged past full no movement at all even if I disconnect it. Tachometer doesn't do anything, and the voltmeter reads 9-12v so alternator isn't charging. All fuses are good lights and everything else works and the engine fires right up like a 165 hour engine should but I can't figure out what's with the gauges. If it was all of them I could understand a bad ground behind the pannel somewhere but it's just half of them. Anyone have any idea why only some gauges and alternator would be effected and nothing else?

[prowlersfish]

Anything with a diode will short instantly ( alternator for example ) some gauges way be more sensitive to this the others .

[Jimmy]

With (2) batteries wired with negative to positive and vise versa, quite possible you could gave had 24 volts push through your system. May explain the pegged meter. I would imagine you may have damaged more components as well. Lucky you did not have a fire (melted wires).

Fuel gage works off resistance. Ignition only works the gage, but could also be fried. Try unplugging the leads on the sender and putting them back on again with wire brushed leades. Slight corrosion can block the very low resistance

Good luck, and hope not more damage.

[AlphaJustin]

Thanks guys I'll replace the alternator in the morning and try to clean the connections for the fuel gauge and see if I can figure out why the tachometer quit it could just not be hooked up there's a few wires disconnected but it's a replacement engine so I don't know. I'll update tomorrow though.

[AlphaJustin]

Any chance there's a place with a good price on a blue alternator to match? It's not worth 100 dollars more to me but maybe 30 so around 100 total? Thanks

[prowlersfish]

If you want blue , your going to have to paint it . I suspect your going to spend a little more then you planed for a marine alternator

[Jimmy]

Prowlerfish is correct. Don't buy an automotive alternator for the boat. Asking for trouble and danger. Always get MARINE certified parts for your engine or anything that goes in the engine room. Yep, They will coat more but it is for a reason.

Gauges etc, you can use automotive.

[The Dog House]

My best guess would be your fuel gauge is dead and needs to be replaced. Hopefully the tachometer is just not hooked up. The alternator most likely also needs to be replaced. As said before, you must buy a marine alternator. It might not happen often, but boats do go "BOOM" when sparks and gas vapors find each other.

[prowlersfish]

As far as gauges go being 45 yeas old its very possible there were gauge issues before the batteries were installed wrong . That topic comes up all the time .

[AlphaJustin]

All good points, I won't put an automotive alternator in I've seem the gifs they also have clearly visible shielding over the coil so if that's there, there must be a reason. Was just trying not to spend 200 dollars is all but time to put on my big boy pants and find the correct replacement which is proving hard enough most alternators im finding aren't correct at all. That's unfortunate about the fuel gauge oem replacement probably don't exist anymore either do they? so I'll have one different gauge maybe I'll put an external with the tank and just keep an eye on it. There are loose wires around the engine but it starts and runs so I'm worried about hooking things up and causing problems.

[AlphaJustin]

Just went to test the sending unit in the fuel tank I think I found the problemunder the wire when I took it off I just put it back so I didn't forget where it connected.

[The Dog House]

All good points, I won't put an automotive alternator in I've seem the gifs they also have clearly visible shielding over the coil so if that's there, there must be a reason. Was just trying not to spend 200 dollars is all but time to put on my big boy pants and find the correct replacement which is proving hard enough most alternators im finding aren't correct at all. That's unfortunate about the fuel gauge oem replacement probably don't exist anymore either do they? so I'll have one different gauge maybe I'll put an external with the tank and just keep an eye on it. There are loose wires around the engine but it starts and runs so I'm worried about hooking things up and causing problems.

The tachometer connects to the coil.



You can see the red wire and black wire from the tachometer connecting to the coil (horizontal black cylinder) in the picture. If the coil doesn't have any wires connecting to it that's probably your problem.

[AlphaJustin]

Mine does have wires connected that run into the loom and disappear but they are connected which is a good sign but also a bad sign. I'm going to have to try to buy one to test if it's just the wires in the loom don't connect to the wires in the dash or if the tach is shot. Local marina sold me on an entire electronic sending unit for the fuel so when that goes in I'll be able to see if the gauge works or not.

[AlphaJustin]

So I put the new electrical sending unit in (checked it first for resistance band at different float levels) and no change in the gauge it's still pegged past full but it isn't touching the wall anymore it's now just floating in the way over full area. I can see the bottom of the tank so it's not full at all maybe a gallon or 2. The light bulb in the tach gauge doesn't work either even though it doesnt look blown and is wired with all the other lights that are lit up. I havent actually started it again to check but I brought the alternator to a shop to have it repaired and the guy tested it and said it worked perfectly so there must be something with my wiring somewhere I am not seeing anything though. This issue persists through each battery on single and both together on with no change. No blown fuses or melted wires anymore that I can see I'm so confused I may just give up and keep the tank full and the throttle at or below half and just use the boat even though it'll gnaw away at my soul.

[prowlersfish]

Make sure you have a good ground in the tank sender , and make sure its a match for the gauge