Seadoo GS Fuel Gauge Circuit Repair

[odonnse]

Hey everyone — new to the forums and already neck-deep in Sea-Doo surgery.


I’ve got a 1997 GS with a completely unmotivated fuel gauge. It was DOA when I bought the ski, and after a summer of guessing how much gas I had left (spoiler: not much), I decided to dig in.


Pulled the gauge this fall and did a little “bench test” science experiment. Applied 12 V to the pink wire and ground to black — which, according to the internet, should’ve made the needle leap heroically to Full. Instead… nothing. Not even a twitch.


So now I’ve fallen all the way down the rabbit hole: removed the acrylic face, extracted the PCB, and started poking around with the multimeter like it owes me money. I’m an electrical engineer by trade, so I’m confident I can track down the bad component and Frankenstein this thing back to life — but before I go too deep into reverse-engineering mode, has anyone already mapped out or repaired one of these?


Would love to compare notes, or even just get confirmation that this gauge isn’t powered by Sea-Doo black magic. Also, if anyone’s got a spare fuel needle lying around, I’d gladly buy one — mine met an untimely death during an overzealous disassembly session.


Thanks in advance, and happy wrenching to all the fellow tinkerers out there!

 

[etemplet]

If you are speaking of the large 3-1/4" gauges those are difficult to find and when you do they are expensive. Prices are very unfriendly. I'd check the fuel baffle first to make sure it is sending a good signal to the fuel gauge.

 

[odonnse]

If you are speaking of the large 3-1/4" gauges those are difficult to find and when you do they are expensive. Prices are very unfriendly. I'd check the fuel baffle first to make sure it is sending a good signal to the fuel gauge.

Yes, that’s the exact gauge I’m dealing with. Do you happen to know if applying 12 V between the pink and black wires should actually make the needle pin to full? From what I’ve read, that’s supposed to be the quick “is-it-alive” test — but mine stayed flatter than my motivation to stop tinkering.
I completely agree that verifying the sender is step one in most cases, but the ski is currently hibernating in storage about four hours away. I’ve just got the gauge with me for some winter bench diagnostics. Based on my pink-to-black 12 V test, I’m leaning toward the gauge itself being the culprit — unless there’s some secret Sea-Doo voodoo I’m missing in the wiring or signal path.
Appreciate the tip though — and yeah, I’ve seen the prices on replacement gauges… definitely “unfriendly.” Makes me even more motivated to revive this one!

 

[mikidymac]

I don't think that circuit is supposed to get 12V, it only uses the resistance of the baffle. But I am no electrical expert either, so take that for what it is worth.

 

[odonnse]

I don't think that circuit is supposed to get 12V, it only uses the resistance of the baffle. But I am no electrical expert either, so take that for what it is worth.

You might be right about that — after digging into it a bit more, I’m starting to think my “12 V across pink and black” test may not have been the correct approach after all. I’ve got most of the internal circuitry mapped out and partially reverse-engineered at this point, and so far it looks like I haven’t fried anything (which is always a plus).

I probably have a few more hours to go before I’ve got the full schematic nailed down, but now I’m starting to suspect the gauge might actually be fine — and that my initial “bench test” assumptions were what needed repairing!

 

[etemplet]

Old wires change color so that is difficult sometimes. Generally 2 pick wires from the fuel baffle send the resistance measurement to the fuel gauge. Usually the purple and black wires see power. Black= common, purple = 12 volts.

 

[lagojaguarasp]

Is it possible to remove the fuel sending unit on those GS/GSX hulls without removing the fuel tank out of the hull?

 

[etemplet]

Is it possible to remove the fuel sending unit on those GS/GSX hulls without removing the fuel tank out of the hull?

I'm pretty sure you can get remove the sending unit. You might have to get ugly with it.

 

[odonnse]

Old wires change color so that is difficult sometimes. Generally 2 pick wires from the fuel baffle send the resistance measurement to the fuel gauge. Usually the purple and black wires see power. Black= common, purple = 12 volts.

That was how I understood it, other than the pink wire also being powered. The issue is the fuel signal goes through the MPEM. So as far as the schematic tells me, its fuel sender -> magic black box -> fuel gauge. If someone had a schematic for the gs MPEM, that would help.