Question about inspecting a gas tank

ERock82

Petty Officer 1st Class
Joined
Aug 14, 2014
Messages
230
Ever since I bought my boat a little less than a year ago, I have never used the original fuel tank that is housed underneath the deck. Instead, I have used an external 6 gallon tank above the deck. The man who sold the boat said it was because the fuel gauge is broken which I can see it is broken. I am replacing my rotten deck and just recently pulled out the original fuel tank to inspect. I would like to use it and get rid of the external tank. It was about a quarter full of rain water from an exposed valve opening on the end of the tank. The tank is very long and short so it is very hard to visually inspect for dirt and debris but the rain water looked clean coming out. Is there a way I can test it out to see if it would be good to use again? These tanks can cost a couple hundred so if not I would just use the external one again.

Also, how do I get the fuel gauge working again? The tank has a circular plate with two wires attached. I assume that is for the fuel gauge. Is there supposed to be something else in the tank to measure the level? Aside from the wires and an old fuel hose there was nothing in or connected to the tank. It is from a 14' Bayliner Capri. Thanks.
 

gm280

Supreme Mariner
Joined
Jun 26, 2011
Messages
14,605
Yes, that circular plate on the top of the tank is where the fuel gauge wires connects. Under that plate is the fuel sensor sender that tells the gauge how much fuel is remaining. If there are no wire(s) connected, that IS one of your fuel gauge problems why it is not working. There could be more problems, but until you connect the wires up to the tank and fuel gauge properly, it is never going to work... As far as cleaning out the tank and having it checked. There are places you can take it to have that done. OR you can clean it out yourself and look see if it looks nice inside and then close it up and pressure it to see if it leaks. Shouldn't take much pressure and if that pressure leaks down, find out where the leak is coming from and fix it... But I would use that tank again if it checks out good. Why not?
 

ERock82

Petty Officer 1st Class
Joined
Aug 14, 2014
Messages
230
Thanks gm280. How should I go about cleaning it out myself? I can only see about 6 inches into it. The tank is a very hazy yellowish plastic so I can't see inside otherwise.
 

GA_Boater

Honorary Moderator Emeritus
Joined
May 24, 2011
Messages
49,038
If you remove the sender plate, you will be able to see inside better. Not great, but better. I think some have used some diesel or kerosene to swish around to dissolve old crud.
 

GA_Boater

Honorary Moderator Emeritus
Joined
May 24, 2011
Messages
49,038
A short piece of chain is also a good crud loosening aid.
 

fishrdan

Admiral
Joined
Jan 25, 2008
Messages
6,989
Pressure test the tank with 2-3 PSI to make sure it doesn't leak. Nuts-bolts-chain- etc inside the tank and shaken will clean it. You could put the tank in the back of your truck for a couple weeks, and driving around will move the bits around and clean it out. I've used Simple Green in a plastic tank and it cleaned it well, rinsed well with water and then dried.

Test the sending unit with an ohm meter to see if it works, the range is something like 0-180ohms (that's not it, but close). I would replace the sender gasket if the sender checks out.
 
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