gas tank discrepancy

[crdenton]

OK, I am going crazy out of my mind. I have an 03 Lanuch. Went out to the lake the other day, and for the first time in my life (25 years of boating), I ran out of gas, of course, in the middle of the lake, with very few boats out. My gas gauge jumped from about a 1/8 full reading to just a tick below empty, and we ran that way for about 15 minutes, after which the boat stalled out and died. Numerous attempts to restart it resulted in it starting and running for a few seconds and then dying again. So, I am sure I was out of gas. Now the puzzling part. After we were towed back to shore, I took my boat home and the next day went to the gas station to fill it up. I was expecting to put 37 gallons in the tank, since the owners manual and sales brochure show an 03 Launch has a 37 gallon tank. Well, I could not put a drop more than 29.5 gallons in the thing. It kept running out the filler neck, and I could actually see the gas down in the filler tube. So I know the tank was full. But for the life of me I am trying to find out about the 7.5 gallon discrepancy between what the owners manual says I have, and what I was actually able to put in the tank. Before you ask, yes I am sure I ran out of gas, and the tank was empty, at least according to the gas gauge and the fact that the boat died. And I am sure I was only able to put in 29.5 gallons. Can someone explain what is going on? The dealer had no idea...
Thanks,
cdr

[jflock2]

I have never seen a gas gauge that really works...I've owned 3 boats (made by 3 separate manufacturers) and they were all the same - the gauges were totally inaccurate. I could share some interesting "out of gas and stranded" stories if you're interested. Now I fill up when she's on a quarter tank...

[flynndog]

I have an 03 comp LTS and do not believe the tank is 34 gallons as stated. I have driven it until the gas gauge read empty and have never needed more than 27 gallons at fill up. Although boat gauges are not percise, I do not think it would be off that much. I am going to run it empty and access the tank under the rear hatch to check it. The gauge accuracy should not affect capacity. If you ran it empty it should take full capacity at fill up. If it doesn't it may not have the correct tank. That is what concerns me about my boat. I also have not found the dealership to be much help.

[jflock2]

I've also heard that the fuel tank hose can not access the fuel in the very bottom of the tank to prevent taking any "sediment" into the engine. Not sure if that is true or not, but it would explain the false readings...

[02LaunchSSV]

Same problem here! Gauge jumped from 3/4's to 1/4 and have never put in more than 25 gallons after boarding for 2 solid days. I said the hell with it and took the boat to my local GM dealer and had a new sending unit and float put in and to this day, gauge never fluctuates and when it said it was empty, IT WAS!!!!!!!!!!!!!!!!

[flynndog]

03 Comp LTS

I took a look at my gas tank and was relieved to find that it does hold 34 gallons. With the float bottomed out (gauge reading empty) there was still 1/4 tank left. Also, my fuel pick up lines run to the bottom of the tank. Perhaps yours do not for some reason, as mentioned before.