Dirty fuel / Fuel Tank

[Mike G.]

Hello all:

I was having some problems with periodic drops in RPMs, and asked the boat yard to take a look. Their comments on my invoice are: "The fuel system is badly contaminated. Drained out 15 gallons of old fuel and replaced with 10 gallons new... Replaced filters...We would recommend that the fuel tank be replaced. It has an old galvanized and copper line."

The boat is an early model Pearson 323 (1977). It once had an A-4 and was replaced with a Yanmar 3GM30 about 10 years ago. The tank is original. I have all of the conversion receipts which indicate that the tank was thoroughly cleaned prior to the conversion to diesel.

My research indicates that the tanks on those early models were Monel. It is my understanding that they have a very long life. Is that true?? Should the tank just be polished and fuel lines replaced? What questions do I ask of the yard that led them to recommend tank replacement?

Thanks for any advice. Mike

 

[Ross]

From what I have read, galvanized tanks for diesel

are not recommended and an Exxon site indicated that copper is not the best choice for fuel lines. But I have never seen annealed steel tubing for sale.

 

[Don S/V ILLusion]

how confident are you in the yar's recommendations?

Copper and steel are not the ideal combination for a fuel system but before replacing both, I'd consider their recommendation to be "too easy". There are a whole host of things which could also cause your rpm to drop, some of which are much easier (read- cheaper) to fix. An indication why I'd tread lightly over their recommendation is that they should know simply replacing the old fuel and filters won't remove all the contaminants on the tank walls which can easily re-suspend in new fuel.

 

[Warren Milberg]

There was a long thread on this type

of problem, and solution, recently. In sum, a friend of mine had his fuel polished. No troubles until then. After, he kept experiencing engine failure after the engine ran a while == and he was away from his slip. In short, the fuel polisher did not get all the gunk out of his tank. He eventually had an access port installed and the tank cleaned -- and lots of gunk came out. He spent a couple of boat units arriving at the conclusion that he could have just replaced his old fuel tank and lines for a lot less money, and lots of tows back to his slip. I would replace the tank....per the instructions of the yard.

 

[MoonSailer]

Did they fix the problem???

If there is no problem with the boat use it. If there is a problem you might consider removing the tank for cleaning. I think that I can remove my person 323's tank. Just undo the connections and then slide it out through the cockpit lockers. IF I ever replace my tank it will be with two tanks that are smaller. Fresh fuel is the secret. Nothing good happens when fuel is aged two or three years!!!! I always keep my tank about 1/4 full unless taking a trip. In 5 years I've had no problems.

 

[s sauer]

Fuel System Options

IMHO, we've seen the discussion on filling or not filling the tank several times on this site; also the discussionon 'polishing', vs installing access ports for cleaning.

A lot depends on how much you use your boat. I personally agree with Moon Sailer that less fuel is newer, fresher and cleaner fuel.

I've also gone the route of installing a clean-out access panel and new CG approved flexible fire resistant fuel lines on a Poly tank with a 10 mic. Raycor fuel filter followed by a 2 mic. Yanmar engine filter and also keep a check on the 'O' ring on the deck fuel fill. Like Warren, I buy a couple gallons of fresh ultralow sulphur diesel at a very active truck stop whenever I plan a trip and add a litttle Cetane boost.

It was the change to ultralow sulphur diesel fuel that led me to add the access panel, clean out the tank and replace the lines along with the new filters two years ago.

I'm personally very happy with this combination and don't see condensation as an issue with the poly tank, although I try to run it down as empty as possible before haul out and put new fuel in in the spring. The Yanmar has OEM soft metal fuel lines from the low pressure pump to the engine filter, OEM reinforced flexible fuel line to the high pressure pump and again OEM soft metal fuel lines to the injectors and the new fire resistant flexible fuel line on the fuel return to the tank.

 

[Mike G.]

Sounds like I should first pull the tank for cleaning?

Based on most of the recommendations below, it sounds like most of you suggest that I pull the tank and try to give it a thorough cleaning. Also, change the fuel lines.

If the tank is in good shape, I would hate to get rid of a good monel tank.

I don't want to rehash the old threads of old fuel/new fuel ... condensation ...
etc. but to answer some of your comments: It is a 30 gallon tank. I have filled 22 gallons this summer. Last summer, I used 21 gallons. Biocides and stabilizers have been added. I have no idea what the PO did prior to last year (it was on the hard for almost 2 years). There was water in the fuel when I purchased the boat. I watched the previous boat yard replace the fuel prior to closing. I also changed the O-ring on the filler cap.

The engine ran great until this incident, and here is what happened: Motored for about 30 minutes at about 2800-2900 rpm. Rpm suddenly dropped to about 2300 then quickly came right back to the 2800-2900 range. Happened about every 10 minutes for the next 2 hours.

Now, here is another interesting fact. This is a very busy marina that sells huge amounts of fuel. I filled 9 gallons probably less than an hour after their tank was filled. Coincidence or not that these problems erupted right after their fill?????? I have asked the marina to advise if they have had other complaints from that fill, but of course, they will only be able to give me one answer!!!

Thanks for all of your input.

Mike

 

[s sauer]

Existing Fuel

From your description, you had water in your fuel when you purchased the boat; that fuel was pumped out--- however you usually can't get everything out of the tank unless you open it up and put a separatehose in to get everything out. The fuel pick-up in the tank is likely not right on the bottom; maybe 1/2" up, maybe it has a screen on it, maybe it dosen't
Anyway you added new fuel & biocide, but let's assume there was a layer of dead algae and/or some water on the bottom. When you re'filled, that crud was stirred up and went into suspension and then quickly cloggged your filters. Water in the marinas fuel could have exacerbated the problem.

A clear plastic bowl on the bottom of the fuel filter would alow you to see what's happening and confirm the above theory.

You could pump out 22 gallons of fuel; cut an access panel in and clean the tank. Or you can keep changing filters over time get the crud out but never be able to know when the engine may cut out. At the very least, use your oil change handpump to pump a couple gallons out by taking the fuel hose off the incomming side of the fuel filter or from the tank pick-up. Let this sit to settle out most crud and water and you should have an estimate of what's in the remaining fuel. I don't see that you'd need to pull the tank and get a new one if you can clean it.

 

[Mike G.]

Thanks for the follow up

Thanks, good advice that I will try.

Mike

 

[MoonSailer]

Maybe you bought bad fuel

I bought bad fuel and it clogged my filters until it was burned. Fortunately I bought less that half a tank. All was well until I bought the fuel and has been since I burned that tankful. I was warned after I had already bought fuel that they had been having problems with their fuel.

 

[EatDrinkHealthy]

Never buy fuel from a marina

I never buy fuel from a marina. They don't turn over enough even for a "busy" place. The remaining fuel sits in the tank over the winter. I am sure they won't add any bio or stablizer before winter shutdown.

I alway use a yellow can and get fuel at a truck stop. You can shine a light and peek into the can to confirm there is no dirt. And then when you fill the tank from the can, use a water separator filter funnel.

Marine diesel are small engines. It doesn't take much to clog the small filters.

 

[reserche]

I had my engine cutting out as a result of water in the fuel tank. I had a racor filter installed, which is great- there was a ton of gunk coming out of the fuel, which became easily visible. We installed new fuel lines. Lastly- pumped out and disposed of all the fuel, and had the tank thoroughly CLEANED and dried out the tank. Then will re-attach. I'm going to the final step of replacing the deck fill- as the gasket may be older and not making a tight seal. My frequent boat washing may be getting some water into the tank each time. SO! Hopefully, no more dead engine in the middle of the channel Will keep you posted if there's any more issues. The deal with replacing my fuel tank was it was custom made for this boat, so getting one the proper size was about impossible, so we opted to clean it instead.