how much fuel is in my tank

[natsgrampy]

89 Sea Ray 200 closed bow with 3.0 Mercruiser IO with 35 gallon fuel tank in the floor
On the water, the motor stalled and it wouldn't start. Gas gauge said 3/4 of a tank of gas, which I thought was accurate. Couldn't recall last time I filled the tank, but thought I had filled it end of last season, and this was the first time I was able to get out this season. I put about 3 gallons in the tank from a jug I had at home.
The boat started and ran well on the muffs. I thought maybe it did run out of gas, especially the way it just died.
I took it to the gas station and filled it up. I t would only let me put 9 gallons in. The filler hose was filled almost to the top.

How can I tell how much fuel is in the tank, assuming the gauge is incorrect? Are there any places I can "look" inside the tank?

Then, if there was fuel in the tank, where do I look to figure out why it died. It was a very hot day, mid 90's, the day it stalled. It is a carbureted engine. Is a vapor lock a possibility

 

[Grub54891]

If you truly filled the filler hose to the top, it tells me the vent hose is plugged. Fuel should have been spillin out the vent at that point.

 

[dingbat]

If you truly filled the filler hose to the top, it tells me the vent hose is plugged. Fuel should have been spillin out the vent at that point.

Not necessarily. Lots of vented cap systems out

 

[Grub54891]

Not necessarily. Lots of vented cap systems out

True, some have checkvalves. Being an 89 , figured it didn't.

 

[harringtondav]

Pull your fuel level sender. Drop in a tape measure and note the depth of your tank and the level of the gas on the tape. This ratio against 35 gal. is roughly the amount of fuel in your tank. It sounds like your sender and gauge may have been telling you the truth. While you have the sender out, move the float up and down and see if the gauge follows.

If so, you may have a fuel delivery issue, bad fuel pump, bad old fuel in the system/carb, or a vent problem preventing fuel draw into the engine. It doesn't take much fuel to allow an engine to idle/rev on the muffs. It takes much more to generate power.

 

[Chris1956]

My '88 Searay had a carpeted removable panel over the fuel tank, behind the seats. The tank had a removeable fuel gauge sender (5 screws). You will be able to see how much fuel in in the tank.

However, the way your motor is acting up, you need to check the fuel tank vent for clogs, and I would clean the antisiphon valve. On my SR, the fuel pickup was removed from the tank, and the outer tube unscrewed from the pickup, exposing a filter, that can clog.

 

[Scott Danforth]

could be a bad vent, could be a hole in the siphon tube 3/4 way up

 

[natsgrampy]

have a day off tomorrow so will check the vent and fuel gauge sender.

will check back here after that.