Fuel tank draining and cleaning

I not-so recently purchased an 82 V20 with OMC 5.7 i/o. The boat has sat for at least 10 years with a full fuel tank.

I have drained most of the fuel out but there is still some residual fuel left. I would like to completely drain the tank and clean it with out removing it. The tank has no leaks and it appears to be in good shape. What methods can be used to fully drain and clean the tank while still installed?

I have installed a new engine and had the outdrive rebuilt. I can't wait to get it out on the water. There are just a few things left to do. The fuel is the major concern at this point.

Thanks in advance,

BassOMaticII

[Franco]

just my 2cents worth - *First go buy a cheap electric fuel pump and 10-15 feet of fuel hose. Cut a long section (7-10 feet) od hose and put it on the suction side of the pump and the rest on the discharge side - make a wiring harness with aligator clips on the end of 10 feet of wire. I would pull the fuel tank sending unit out, and the siphon tube from the fuel tank.
I'd look for a cheap C02 fire extinguisher - gas only, no powder and discharge it into the tank a little at a time - then I'd *put a mixture of simple green and water into the tank and swirl it around as best as possible - tilt the trailer so it all runs to one end and the insert the suction hose into the tank, you may want to substitute some metal tubing for some of the hose - and put the discharge hose in an old gas can- connect to the battery and suck all the old stuff out - it should only leave a small amount in the tank. Just my thoughts!!
Note - C02 makes it safer to work with, and keep the electrial stuff away from the fuel.

[reelapeelin]

I didn't know that about the C02...sounds good...if you can somehow WEIGHT the end of the tube that goes into the tank so that it STAYS on bottom(and so weight does NOT come off)might help loosen crud on bottom of tank...once you've done all that, get a good filter and be prepared to change element regularly til gunk flows thru...and install a fuel/water seperator...good luck w/it...keep us posted...don't blow your a$$ up... :o...

[Franco]

Just recommended that because in the old days when we were into race cars, we would cut and section gas tanks, filled them with C02 so they would not explode when welding ot cutting them. My grandfather ended up in the neighbors backyard after cutting an old tank that aired out for weeks before he cut it open!!!

[Mac_Attack]

Weigh the tube down by wrapping solder around the tube, pinch the end of the wrap slightly so it does not slide off. Bill Mc ;D

Thanks for all the input. Went to Pep Boys yesterday looking for a universal electric fuel pump. They had no idea what I was talking about. They asked me what make and model car I was working on. I did'nt tell them.
Saw one in JC Whitney that I will order.

Co2 evacuation is a good idea. My wife has a 55 cu ft helium tank that I could use.

I'm very cautious with fuels. I used to work with things like 100% Hydrogen Peroxide, 100% Hydrazine, Amonium Perchlorate and the like. Boats aren't rocket science but I was a rocket scientist!

Thanks again,

BassOMaticII

[Franco]

Man, if you can adapt some of the rocket stuff to an outboard, you would have more fun than the law allows

[reelapeelin]

We are ZOOMING, now!!!... ;D...

[jaysea]

when i bought my v20 ,i had to drain my tank also,i removed the fuel gauge from the tank an used a hand pump bilge ,an pumped it rite out into 5 gal pailes let it all settle an put the good stuff in my old p/u truck an used it up,that sound easy ahh 8)

[macojoe]

well I removed my tanks and then empty the fule then I used a good degreaser and washed them as good as i could. then rinsed well and let dry in the sun.

My friend did the same as you when it was in the boat, the small amount left in the tank he used rags to sop it up.