fuel gauge ???

[buckw13]

i recently bought a used boat and i am having a couple of issues. First off, the fuel gauge reads half full when it is out of the water but it reads full in the water. I am going to fill the boat up to see which is right but why does it do this. Also my tilt/trim switches are wacky. the one on the throttle will take the engine down but not back up and the one on the dash will take it up but not down. any answers would be greatly appreciated. The boat is a 1990 Larson Senza 210 lx br with the mercruiser 350 alpha one 260 hp. Also what should the top speed for this boat be. Right now it has a five blade stainless prop on it but i cannot find any numbers on the prop. Thanks for the help

 

[Silvertip]

Re: fuel gauge ???

Fuel gauges read differently because the attitude of the boat changes the attitude of the fuel tank. Fuel tanks are long, narrow and very shallow so the float arm on the sender will read the "level" of fuel. The boat probably sits fairly level on the trailer but will sit stern-low in the water. Once fuel level get to about half, fuel sloshes around and attitude of the boat will affect the gauge reading. There is nothing you can do short of replacing the sender with a more expensive linear version or buy adding a fuel flow monitor. Filling the tank proves nothing since it will obviously show full. The trick is fill the boat (on land or water) and then refill on the water when the gauge reads half. You then know how much fuel you actually have when the gauge reads 1/2 sitting in the water. You have probably noticed that the gauge dances around under way and even running on smooth water it may read different than when sitting at the dock. It's all because the way the sender works.

 

[buckw13]

Re: fuel gauge ???

I filled it up this morning with 18 gallons. It now reads full whenon the trailer. I was told it has a 60 gallon tank. So by what you said the gauge seems to be working ok. It was reading full becaue of the boat angle. So when the boat gets low on gas it should read fine. It will just say it has more gas on the water than the trailer. so i should be ok with this gauge as long as i don't let it go all the way to empty in the water......

 

[Silvertip]

Re: fuel gauge ???

All you've proven is that the guage reads full when you KNOW the tank is full. The next step is to refill on the water when the tank reads 1/2. If you have a 60 gallon tank and it takes 40 gallons to fill it when it reads 1/2 on the water, you know there is only 20 gallons left. This is why its so important to know how the gauge reacts on the water vs on land. On land you don't care what it reads. On water you do.

 

[buckw13]

Re: fuel gauge ???

thanls for the reply. I will keep this in mind and make sure i check that when i run the gas in the boat

 

[jim.little]

Re: fuel gauge ???

FYI, my Senza fuel gauage does the same thing.

BTW, it definitely is a 60 gallon tank. I bought mine new and have run it out completely before...took almost 60 to fill.

I have original brochures for the bot if interested. Let me know.

james.little@covidien.com