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Fuel Tank Cleaning/Replacement

11YearItch

Member
During the past month that I have had my recently purchased 1988 Spectra 171 powered by a 1988 Evinrude XP 150 V6 in the water I have experienced a couple of problems that lead me to think I may have to remove the fuel tank for cleaning and replacement of the filler, fuel, and vent lines.

Problem 1: Although the engine runs really well at boat speeds over twenty miles per hour at lower speeds it is rather jerky with a slight vibration. It feels like the engine is missing or running rough and several times the engine has died when running at a low rpm. Also sometimes when starting the engine for the first time in a day I hear what sounds like a loud cough (water in the gas?). I have always added gasoline stabilizer whenever adding new gas and over the past month startup has improved somewhat, but not totally.

Problem 2: Passengers riding on the back bench seat are complaining of a strong gas smell when the boat is running at low speeds.

Question: How big of an effort is it to remove the fuel tank from under the bench seat without damaging the seat vinyl and where can I purchase any new parts (tank, filler hose, vent line, fuel line, gauge)? Advice will be greatly appreciated.
 
Could be low speed jet plugged, do you know if the carbs have been cleaned recently? The cough at start up is a shortage of fuel, most older motors do it, I wouldn't worry about that, probably just needs a carb cleaning.
 
Thanks John, I'm not sure about the carbs but the marina I purchased the boat from told me the carbs had been rebuilt in September 2011. Maybe I will spray some carb cleaner into the carbs and see what happens.
 
That won't clean the carbs. If they need to be cleaned it's the internals that need it so yyou'd have to disassemble them. Could be as simple as carb and timing adjustment (aka link and synch). I would pump out every last drop in the tank, drain the carbs, put some fresh fuel in, pump the bulb with the fuel line disconnected at cowling, pump a pint out by squeezing the bulb to clear any contaminants out of the bulb, then hook up the fuel line again and take her for a ride. Change the fuel filter under the cowl too if it has one.
 
Thanks atc, Your advice makes good sense and seems easier to do than removing the tank. I think I may still have to replace the fuel and vent lines to eliminate the gas smell.

Another question for you. I purchased my boat from Greenwood Lake Marina in Hewitt, NJ this past June. I was told the boat had been on Greenwood Lake for at least 10 years. By any chance do you recognize the boat? The name "11YearItch" was on both sides of the boat when I bought it.
 
Could also be the floats are set too high, which you could resolve when cleaning the carbs. If you plan to clean the carbs out, make sure you order complete gasket kits for them. Another issue could be the seal on the gas tank where the sending unit mounts. If the gasket is worn out, a little gas will leak out when the tank is full and at a certain angle. You will also get strong vapor odors that leak out if that gasket is shot.
 
Thanks Ramifications for the good information. I had never thought about the tank/sending unit gasket but that sounds like it could be the source of the gas fumes to the back seat. I will check it closely when I replace the fuel, vent. and filler hoses.
 
If you do end up removing the tank, remove the rear seat completely, it makes the job much, much easier, and allows you to clean the seats really well while they are out.

When I purchased my Starflite last year, I noticed that the gas tank mounting brackets were fatigued and cracked after 24 years of use. I removed the tank and sent it out to a local aluminum welding specialist shop. They cleaned & tested my tank before and after welding the new brackets on, and also noticed a hairline crack at the "bung" where the filler hose connects to the tank. About $130 later I had a tank as good as (if not better) than new because they beefed up the mounting brackets for me. I took the opportunity to replace my fill hose, vent hose, and fuel line/primer bulb at the same time. All the rubber hoses were rock hard and ready to crack. I also found that the filler neck was not grounded to the tank correctly either.

While the tank was gone at the shop, I scrubbed my bilge sqeaky clean and rebuilt the lower seat base. Totally worth the effort, it gave me a chance to really inspect my boats stringers, transom, and floor behind the rear seat.
 
Fox88gt, all my hoses are rock hard also so I would like to do what you did but I haven't been able to figure out how to get the bench seat out without destroying the vinyl. All the vinyl in the boat is in such good shape that it is hard to face up to destroying any piece of it, but I may have to. Thanks for sharing what you did.
 
Does the rear seat in your Spectra flip open? Mine had angle brackets screwed down to the floor to keep the seat base in place.
 
fox88gt, this morning I took a harder look at how the rear seat box is attached in my boat and it looks like by removing a few screws it might flip open. I plan to pull my boat out of the water next week for winter storage and then will take the screws out and see if I can get to the fuel tank. If so, over the winter months, I will have the tank cleaned and repaired if necessary. Again your help is appreciated, thanks.
 
fox88gt, this morning I took a harder look at how the rear seat box is attached in my boat and it looks like by removing a few screws it might flip open. I plan to pull my boat out of the water next week for winter storage and then will take the screws out and see if I can get to the fuel tank. If so, over the winter months, I will have the tank cleaned and repaired if necessary. Again your help is appreciated, thanks.

Ok, I now have my boat out of the water and the rear seat box out so have access to the fuel tank. Much to my surprise the tank is not metal. It is a plastic tank manufactured by INCA. At this point I have not been able to determine where the gas fumes are coming from so once again I am not sure how to proceed. I don't see any cracks in the tank or any signs of gas leakage. The seal where the sending unit attaches to the tank looks ok. The three rubber fuel lines are hard as rock so I will be replacing them. I don't know if this will get rid of the gas fumes. Advice from anyone that has had a plastic tank cleaned and/or repaired will be appreciated.
 
Push on the top of your tank a few time to create some pressure and it should cause the fumes to come from whereever they are escaping.
 
Thanks RNGRDVE, I pressed on the tank and did smell fumes so have decided to remove the tank and have it pressure tested and, if good results, cleaned. Today I siphoned out the eight gallons of fuel in the tank and next week will be removing it.
 
As for the smell of fumes, I get them once in a while and that has been coming from the vent in the motor well. (Depending on the direction of the wind) You are right to replace all the rubber fuel lines. It is a cheap insurance policy against fire while out on the water.

Last year my 96 Johnson 200 V-6 did some of the same problems at low speed like you described. Eventually it stopped running (Coming back to the dock after a ride) about 10 feet from the dock. :o

After testing I found out it was the timer base that went bad. If you can, you may want to have that tested. Once it fails you are paddling home or looking for a tow. Since you have completed your season it is a great time to prepare for a trouble free season next year. :rolleyes:
 
If I push on the tank in mine you can hear the air coming out the vent in the splashwell and smell the fumes.
 
Thanks JT, in the Spring I will be taking my boat back to the marina where I bought it for some warranty work so will discuss the timer base with the marina mechanic.
 
atc, the fumes in my boat seem to be coming not only through the tank vent but also from other areas around the tank. Thanks for you input.
 
Sounds like it will be a good idea to have the tank pressure tested. I've always wondered what the effects of ethanol would be on a plastic tank. The stuff eats rubber fuel lines, could it effect a plastic tank?
 
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