dirty diesel

[Rakuflames]

I have a 31' 1983 Hunter with a brand new engine that is intermittently sputtering, coughing and dying. If we anchor and sit a while, we can run again, but not at optimal RPM's. I have realized that the previous owner took care of *nothing* and that it's only by the grace of God that I have a sound boat.

I believe there's sludge in the fuel tank and I don't want to screw around with it. I *think* the fuel tank is at the bottom stern of the boat. Can anyone confirm that for me or provide me with a good drawing of the boat's design? I haven't been able to find one.

Is there any reason I couldn't put an access port in the top of the fuel tank? It would make it much easier (and therefore cheaper) to clean that tank out.

The engine is in very good shape. I don't want to risk scewing up my injectors. Any help appreciated!

 

[Nelsonhow]

I have an 83H-30 so i don't know exactly where your tank is. It sounds like you have an air or dirty fuel problem. Have you changed the 2 filters? If so did the problem go away ? If it came back with dirty filters again yes you probably need to clean the tank. Yes you can add a inspection port but as a temp fix you might just remove the fuel sender unit from the top of the tank then use a hose and a fuel transfer pump (you can get one that attaches to a drill from harbor freight for about $15) to pump out the old fuel. I drain it then strain it with a bajha funnel filter and dump it back in and bounce the boat around a bit or go for a fast sail. Do it a few times then discard the old fuel and start with new. Remember to put the sender back on the tank. There are companies around who will "polish" your fuel which is supposed to do the same thing.

Also check the thin rubber seal on the diesel filler cap. They go bad and are easy to replace from a hardware store or auto supply. If you fill is on deck and the seal is bad t can let water into your tank. Less of an issue for me since my fill is under the stern lazarett.

 

[Stu Jackson]

Back in the days when your boat was made, builders put inline screens in the ends of the fuel pickup tubes inside the tanks. They thought they were doing skippers a favor - NOT!

Catalina, at least, stopped doing that in the early 90s. Check to see if you have one, if so, remove it.

 

[Bill Roosa]

Before you go tearing things appart try this; take the fuel tank filler cap off and see if the problem goes away. it may be that all you have is a plugged up air vent.
Always check the easy quick things first. you eventually save yourself a lot of work.

 

[Rakuflames]

I have an 83H-30 so i don't know exactly where your tank is. It sounds like you have an air or dirty fuel problem. Have you changed the 2 filters? If so did the problem go away ? If it came back with dirty filters again yes you probably need to clean the tank. Yes you can add a inspection port but as a temp fix you might just remove the fuel sender unit from the top of the tank then use a hose and a fuel transfer pump (you can get one that attaches to a drill from harbor freight for about $15) to pump out the old fuel. I drain it then strain it with a bajha funnel filter and dump it back in and bounce the boat around a bit or go for a fast sail. Do it a few times then discard the old fuel and start with new. Remember to put the sender back on the tank. There are companies around who will "polish" your fuel which is supposed to do the same thing.

Also check the thin rubber seal on the diesel filler cap. They go bad and are easy to replace from a hardware store or auto supply. If you fill is on deck and the seal is bad t can let water into your tank. Less of an issue for me since my fill is under the stern lazarett.

Thanks, but the issue isn't water, and I want to clean the tank out completely. The engine is brand new and I don't want to do anything except a complete solution. The the question is really about where the tank is and whether I can put an access port in.

 

[Richard Bryer]

I have a 34 the same age so I am guessing the tank is in the same place- starboard side locker under the seat in the cockpit. I hope you are thin and flexible- it is a tight fit to get down to it. Open the locker and you can see the tank. I did cut a hole in mine and clean it- I took out about a gallon of stuff that you would swear came out of your eavestrough except for the odour. I coveredthe hole with 3/16 Lexan and sealed with Permatex.

 

[Stu Jackson]

Richard, when you cut the holes for the screws, how did you avoid droppings into the tank? Are they just sheetmetal screws?

 

[s sauer]

Follow you fuel filler dow from the decklevel and youwill find the fuel tank, most likely inthebottom of the sail locker.

I think you get the best results in getting rid of the existing contaminated fuel. replacing the fuel filters and maybe new fuel lines considering the age of the boat. Google Seabuilt Access Ports; install at least a 4" to 6" port in the top of the tank so you can physically wipe out any sludge and wipe down all the interior surfaces with alcohol saturated rags.
Re-fill with five gallons of clean new fuel; replace what you use as you use it so you don't end up with a tank full of 'old' fuel. For the cost of the fuel polishing and new filters you have a clean system and can inspect or clean it any time you feel you need to.

 

[Sail123]

Diesel fuel today is not what it was when older engines were invented. Diesel fuel today is not as good as it was ten years ago. A diesel additive to bring back some of the old diesel properties may help, may not. You should check into that with a marine mechanic.

Also todays diesel can get a growth of fungus started growing in it, that clogs filters, and can make a big mess. An adtive to inhibit the growth of fungus is a real good idea.

 

[Joe Mullee]

Dan Johnson told me about www.seabuilt.com

Expensive but with my concave fuel tank it sealed it nicely.

 

[Richard Bryer]

I drilled the holes with a finer bit- I cant remember the size, then turned the screws in, removed them and cleaned the inside out carefully and made sure no bits were clinging to the underside of the holes. The holes in the Lexan ( actually it was just a polycarbonate not a Dupont product-) are larger and the screws are just self tapping sheet metal ss screws and washers. Think my total cost was <10$. It has worked fine for 5 years

 

[Steve Dion]

I has been a while, but as I remember the fuel tank sit right on top of the muffler. The fill hose goes right from the deck down into the tank. I do not know if you can remove the tank through the lazarette or take it out from the opening under the sink. Then you can just pressure wash it and reinstall.

You can also get a pump and recirculate the fuel through a filter and see how that works. Have you removed the fuel pickup tube to see if there is a screen on the end of pickup tube? You may have crap accumulating on the screen which you can remove and let the filter do it job.

I would NOT install a clean out unless you purchase a fitting like mention above http://www.seabuilt.com/ . Otherwise you wil probably be fighting a leak for the rest of your time with the boat.

 

[Scott]

On our '86 h-31 the fuel tank is in the lazzarette aft starboard side. Probably same as on your '31. Hope I answered your question.

 

[Bill Roosa]

Why do you think your problem is in your tank?
Engines sputter for a variety of reasons and I'm not seeing the diagnosis.
It could be that the good Lord has indeed spared the boat and is trying to see if you will listen to that small voice in your head.
Check the tank air vent.

 

[Bill Roosa]

The fuel filter will catch those big metal shavings from the inspection port install. Also you are going to actually clean the tank once you install the port right?

 

[Robert 47]

I go through this every season at our harbor. Some owners just don't care about marine diesel maintanence. Before you do anything, get 1 or 2 new fuel filters. New. Then I would suggest you get rid of all of the old diesel fuel.
You can do this buy getting a 12v pump at any auto parts house, and while you are there get some "SeaFoam" cleaner. This stuff is great. We use it in our repair shop all the time. Get a couple bottles. It is expensive, so don't cut corners. Then get some Power Service fuel conditioner. Read directions on bottle and put in your tank. This works wonders.
After you get the fuel out, put the SeaFoam in and sloush it around real good. Leave it in for several hours, then pump it out with your 12v pump.
I have a plastic fuel tank on our 1987 Hunter 31. I don't know what kind of tanks they put in the earlier models. Maybe some of the other sailors on the site can help you out with that.
Once you have done this, there is no doubt your fuel system is in good shape. You may want to put a new air filter in if it needs one. That should help you out with your problem. If after you have done this and you still have a problem, I would look at your lift pump, and fuel hoses.
I wanted to put an inspection plate in my fuel tank, but the ones I found are redicoulous in price, and they are for metal tanks, not plastic. I am wanting to put a fuel guage on our boat as well. I post that project when I get to it. Am replacing all of the wet exhaust hose this weekend, so I will be very busy I think. Good luck.

Robert 47