Questions About Fuel Tank Cleaning

[Lancer76]

1976 Chris Craft Lancer with same model year Mercruiser 233 and MC1 outdrive.

I have only been on the water twice in 2019 (short season in Maine). I noticed that the engine starts and runs great until I've been 3/4 throttle for 10-15 minutes or so. At that point, the engine drops out as if its run out of fuel. In fact, I believe the engine is running out of fuel due to a fouled fuel filter. The boat will restart right away and I can idle around for hours. When I push the throttle open again, the same thing happens.

Came home and removed the fuel filter, which I installed mid to late last season. The picture below shows some of the sediment that accumulated in the filter. Based on this, I am assuming I need to clean my tank. The other picture shows my tank. I have great access to it.

I've watched videos where folks have cleaned there tanks by recirculating fuel from the tank through a filter or two and then back into the tank. That seems like a reasonable idea when your access to the tank is via a pie plate access panel. My access is quite different.

I am thinking of siphoning the fuel left in my tank into my truck and fuel containers, I am then thinking of pulling the tank and cleaning it with some lower vapor pressure liquid (maybe diesel). I'll add the diesel and slosh it around to get the sediment into suspension, then pour it out of the tank through one of the holes. The spent diesel will be disposed of.

That's my thought but I'd like to hear other ideas. Thanks .

 

[wellcraft-classic210]

That sounds reasonable -- I have heard some using repeated flushing with water based detergents ( to reduce disposal concerns ) it their is a lot of crud left in the tank.

Plastic vs metal would require different cleaners -- and drying the tank would be important as well.

 

[Scott Danforth]

Your metal tank is rusting from the inside

You will need to clean and then inspect. If there is significant rust damage, you may need to replace

I would drain, then fill with oxalic acid and water. Let sit, then drain, and inspect

 

[scoflaw]

Unless you hate your truck, forget that idea. It's spring, burn some brush.

 

[Lancer76]

Well, I've already lit off two brush piles this spring. Not sure I have more to burn :joyous:. Also, I dont like using gasoline for that purpose - vapors go BOOM to easily.

I will filter the fuel before using in another motor.

Oxylic acid is a good suggestion and I've seen where others use muriatic acid, too. I'll try one of those and report back.

Anyone have experience with POR15 tank coating? If so, can you recommend it or against it?

 

[achris]

I've used the POR15 system, but only on the outside (scuba tanks). Works remarkably well. There is a fuel tank specific lining system. Can't remember the full name, but it starts with 'Red'...

Chris...

Edit: Red-Kote

 

[scoflaw]

I've done several tanks with excellent results. Lengthy 3 step process and you have to be able to turn and flip the tank in all possible directions to coat everything.

 

[Lancer76]

I pulled the tank and cleaned it with water and soap and water. There was some debris in there. Some looked like regular old rust, but some was ferrous but was hydrophobic (see picture). As you can see from my previous picture, the tank is a steel cylinder. Toward the bow is the hole for the fuel level sender. Toward the stern end (which is typically lower) is the hole for the fuel pickup. One picture shows the bottom of the tank at the fuel sender (bow) end, while the other shows the bottom of the tank at the fuel pickup (stern) end. The front end of tank is like new. Not a problem. Looking in the stern hole, there is surface rust. The rust spot is triangular, about 5 inches at the base and about 8 inches in height. Not too bad at all.

The tank appears galvinized or treated somehow. You can see this in the fuel sender (bow) hole picture. If it were you, would you treat the stern end with muriatic acid to remove the remaining rust and then coat with Por15 or the like? Or would you leave it alone as good?

Thanks.

 

[Lancer76]

To close the loop on this thread, sort of, I used some muriatic acid to remove the rust from the very bottom of the tank and then applied Red-Kote.

Ran the boat yesterday with few filter but still have issue with engine dieing after a few seconds at full throttle. Will replace fuel lines and verify float level. Anything else? Here's a restatement of the issue

"​I have only been on the water twice in 2019 (short season in Maine). I noticed that the engine starts and runs great until I've been 3/4 throttle for 10-15 minutes or so. At that point, the engine drops out as if its run out of fuel. In fact, I believe the engine is running out of fuel due to a fouled fuel filter. The boat will restart right away and I can idle around for hours. When I push the throttle open again, the same thing happens.​​​​​​"

 

[dohcdelsol93]

Red kote. We treat lots of tanks here at my shop for mostly outdoor power equipment some hot rods and more than a few classic motorcycles..

first off acetone. Get any varnish out of the system then you have some options.

To remove rust you can use 50/50 muratic(sp?) Acid and water. Electrolisis works too. Dilute about half a cup of washing soda in warm water, pour it in the tank. Then fill tank up with water. At top of tank make some sort of insulator and slide a section of rebar into the tank. Make sure rebar is secure in isolator(wood, plastic, rubber) make sure it doesn't touch any part of the tank.. Attach a battery charger neg to tank and pos to rebar. After 2 days remove and clean rebar. Repeat until no rust appears. Tank will be clean. May take a week or two but harsh acids are not needed. All the rust will move from tank to rebar. The rebar will look 10 yrs old when you're done.

wash tank out, then dry then clean with acetone. Then dry for 24 hrs. Then redkote. I then put it in front of a fan for a week. 7 full days to cure. Then por 15 the outside of tank. Redkote will fill pinholes. Por will also fill pin holes. Not recommended for a boat but many motorcycles are on the road today with oem tanks because of this.

tank must be removed for this process. Ive seen boat tanks sealed with jb weld, id trust properly applied redkote over jbweld any day. Personally if the rust looks bad id just replace the tank, surface rust is ok. Pitting is not.

good luck.

 

[dohcdelsol93]

Im properly cleaned or cured red kote can and will break free clogging fuel lines and carb. All fuel lines and fittings need cleared with dry compressed air sevral Times before redkote cures.

rust in fuel tank = rust contaminates in lines, filtet, fuel pump and carb.

 

[HT32BSX115]

Ive seen boat tanks sealed with jb weld, id trust properly applied redkote over jbweld any day. Personally if the rust looks bad id just replace the tank, surface rust is ok. Pitting is not.

good luck.

I had a 1966 MarkTwain 18ft I/O with a steel under-bow (18gal) tank that finally rusted through and started leaking.....I ended up removing the tank and replacing it with a 26gal aluminum tank. It didn't cost all that much and worked well.

I wouldn't EVER try to use an old severely rusted steel tank in any boat because the risk of future leaks are too great.

That under-floor area is perfect for either an aluminum or poly replacement tank. You might not be able to get an off the shelf tank of the same volume to fit but you can get pretty close.

Moeller has a variety of tanks as does RDS

You didn't post the dimensions of your tank or where the tank is installed but here's an example of what you could install to replace what you have (if it fits) and you can buy one right here on iBoats....

http://ww2.iboats.com/18-Gallon-Bel...4064251--session_id.540192130--view_id.732616

The company above (RDS, sold right here) also makes custom tanks. It might be expensive to get a "one-off" tank to make but it's better than 3rd degree burns(or death) ....... A new tank off-the-shelf tank + install might be about as expensive as the cost of fuel for a week of skiiing and pleasure boating.....

I would NOT use a gasoline tank in a boat that was "fixed" using JB weld, POR-15 and/or "sloshing" sealant......Those are great for cars and motorcycles. Not so much when you're right next to the tank in an enclosed area

Just saying.....


Regards,

Rick

 

[Lancer76]

"I wouldn't EVER try to use an old severely rusted steel tank in any boat because the risk of future leaks are too great."

I am confused - Who said the tank was severely rusted?

​​​​​​The tank did not have significant rust. It is constructed of 1/8 inch steel. There was very minor surface pitting, which I treated with acid, neutralizing caustic solution, water, acetone and then red kote. There is no threat of a leak so no need to put in a poly tank. If there was even a hint or possibility of a tank leak, I'd replace it. But as it is, the tank is plenty solid.