37c fuel tank cleaning

Jun 18, 2006
49
hunter Cherubini Hunter 37 cutter Cocoa Beach
First picture is looking through the hole that the fuel gauge sits in on the fuel tank, down at the fuel intake pipe. Second picture with the red arrow shows the end of the pipe where fuel is sucked up and delivered to the engine. Obviously there is way too much gunk in that fuel tank. You can see from the filters how nasty it was. I used a little electric pump to empty the fuel tank out into 6 gallon Jerry cans. It is a 38 gallon fuel tank according to the tank tag. I'm going to use one of my outboard motor fuel tanks and fill it full of diesel and use that to run the motor with until the main tank is cleaned.
Cleaning the tank will be accomplished by putting about 10 gallons of gasoline in it and hooking up an electric fuel pump that will draw fuel out of the tank, through a filter, through the pump and then back into the tank via the fuel return fitting. The pump will cycle continuously and I will check the filter often as I'm sure that I will need seven or eight of those clear filters that are 20 micron. Once I get out sailing in open ocean, the 10 gallons of gasoline in a 38 gallon tank will slosh around real good and the solvent action of the gasoline will dissolve all of the gunk and I figure by the time I get to Brevard I will have dissolved everything that needs dissolving and then I will pump the gasoline off through a smaller filter, 10 microns as opposed to 20 microns, and I will put it in my car's gas tank. The car has a single throttle body injector so the orifice isn't so picky. but a 10 micron filter should have the fuel clean enough to use regardless.
I could have built my dream catamaran with all this money and effort!( been working on the boat full time for 4 months) But having a fuel issue and having to change a fuel filter, and it's always at a very inopportune time, middle of the night big waves nearing a lea shore, is no fun. If I ever get the thing in the water before I croak, it will be reliable! Me on the other hand, I'll never be reliable.⛵
 

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RitSim

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Jan 29, 2018
455
Beneteau 411 Branford
On my previous Catalina 30, I opened the fuel gauge hole and saw gunk. I thought it would be nearly impossible to clean the tank thru the gage hole. I used a 3" hole saw to cut an access hole. My tank internals were all covered with a dark film but little of it was loose. Purged the tank and hung a low voltage light thru the gage hole. Used a solvent to clean the tank insides completely. Cut a piece of 3/16 aluminum into a 4.25" circle. Carefully marked 24 holes and drilled with the tap drill for #10 screw. Marked the lid location on the tank and used the drilled cover as a template. Checked the tank interior for chips. Then tapped #10 machine screw threads into the tank. Drilled the cover plate holes to clearance holes for #10. Cut a rubber/cork gasket (diesel tolerant) and installed the cover. worked for years with no cover leaks.