Flushing Fuel Tank

[JohnV8r]

Guys,

I need some advice on how to prep my fuel tank for the conversion from gas to diesel. Based on the response to the photos I put up and Capt. Patrick's assessment that it doesn't look to be in bad shape, I am going to keep my existing fuel tank. However, I want to make sure before I put any diesel fuel in that I have flushed the tank as thoroughly as possible.

I have removed all of the gas that I can see at this point. What is the best way for me to "stir" the tank with some removable liquid to ensure that any dirt, etc, is removed before I put diesel in it?

Alternatively, should I put diesel in and set up a fuel polisher for a few days?

Can I/should I "stir" the tank with something like an aquarium pump to try to create enough turbidity to keep any dirt suspended?

Thanks in advance,

John Vietor

[CaptPatrick]

John,

How clean/dirty was the gas that you removed?

If it wasn't that dirty, I'd just put in 30 gal or so of diesel so that you can get through the repower start up and brief runs then, once in the water again, top off the tank and closely monitor your Racors, changing the filters as often as necessary. If you get less than 5 hrs on the first two filters per side, then have the tank polished.

"rinsing" out the tank with anything other than diesel fuel or, at the worst, plain water is risky business...

[JohnV8r]

Patrick,

I'm not really sure what is dirty and what is not as I've never drained a tank before. There was some sediment in the bottom of the chamber I could look into through the inspection plate closest to the transom. I thought it looked like most of it settled out in the back half of the last chamber of the tank when Shambala was coming up on plane. My biggest fear is that of the unknown - in the areas I can't see because of the baffles.

If I want to have the tank polished to be safe, should I fill the tank up completely with diesel and then have it polished or am I better off with just 30 or so gallons to polish up what is in the bottom of the tank?

As always, thanks for your help.

Sincerely,

John Vietor

[CaptPatrick]

John,

Initially you're safe with only 30 gallons while on the hard. No need to be carrying all that weight while on the jack stands and you'll probably use less than 10 gallons before launching. Adjust your blocking so that the boat is clearly bow proud and higher on the starboard side so that 98% of what's in suspension drains back into the aft corner below the access manifold. You'll be fine...

[JohnV8r]

Thanks Capt Patrick!

[matt ciarpella]

The boat I have is 1973 from florida. After the diesel conversion I could not keep the racors clean. Had the tanks flushed and still the same results.
Decided to get to the bottom of the issue, literally. Took a power saw set to 45 degrees and cut a hatch center of each baffle. Could not believe the amount of what looked like petrified fuel was in the bottom, average 2" thick. Like a rust colored granular stone dust/ sand mix. Vac ed it out scrubed each section ceiling and all walls. Thickened resin to set each hatch back inplace, cloth over the seams. Cost nothing to fix in two days. No problems since.
John if you find issue after the flush, you may want to consider this method. Best of luck
Matt

[Tony Meola]

John

When we repowered, no issues. When I removed the fuel I had very little sediment. We started out with 50 gallons of diesel then filled it once in the water. Not an issue. If you did not have a lot of sediment when you pumped it out, you should be good.

[JohnV8r]

Thanks Guys. I appreciate the feedback!