If it has a bad ground, it could be heating up and contact improves
That said, most gauges use senders 180 (cold) to 33 (hot) ohms. The gauge is pegging so the gauge wire might be grounding out. If you have European gauges they work in reverse (cold low and hot is high resistance)
The gauge...
Never seen any fiberglass boat with on of those, looks like the ones used on watercraft like my Seadoo, Yamaha
From the looks of the sealant around it, I'm thinking someone replaced it with that type. If the one Yag doesn't work, look at a local watercraft dealer
Your first comment gave me the impression it didn't stop and kept going until it was re-torqued. If that isn't the case then take the other guys thoughts
Being retired we don't go out on holiday weekends. Do go to see my 1st Great Grand Girls BD party. All good there, and there will be a 2nd GGG come October, even better 😀
Right now its anyone guess. Start with removing the plugs to see if any are wet. If water is found then may have blow a head gasket.
See if a plug wire came off, and the distributor cap and rotor look good
New to you boat, was the raw water impeller changed?
Did you notice what the Temp...
Depending on access it could be better or worst. Your fuel pump is under the port side of the motor and behind the motor mount. Its in a black plastic box.
The antisiphon valve which connects directly to the fuel tank and has a barbed end which the rubber fuel line connects to. It's a spring...
No, because a Bimini would be an option for most boats. There should be a light socket around the stern for a long pole light. Requirements it it would have come with a pole light but marina would not leave it in the boat
Two ways to test pressure.
Can get Merc fitting 91-806901 buy removing the fuel line at the TB.
On the opposite side of where the fuel line connects will be a plug. Remove the plug (item 3) and find a adapter (don't know the thread) to connect gauge...
