1989 23WA Seacraft fuel tank replacemnt/maybe?

[gss036]

Let me start with yesterday. It was the last day (until 7-1-09) for salmon fishing here in our area and I was determined to go. It was windy and 3 ft chop, still fought my way out to the area I wanted to fish, just as I got almost there, my Honda started surging. I knew I was running with only about 25 gallons of fuel and brought along an extra 5 gal container in case my Northstar fuel flow gauge was wrong, as it turned out it was right on the money, said I had 26.5 gallons left, I pulled 26 gallon out of the tank. I had started to season with 75 gallons. Obviously the rough ride really washed the inside of the fuel tank and mixed things up.
A quick check showed that the primer bulbs on the main and Yamaha T9.9 kicker were sucked down flat. Thank goodness I had an extra 3 gal tank for the kicker (carried it for years and never needed until now), disconnected the line from the main tank and hooked that up and fired up the kicker and managed to get back away from the shore line, I had been pushed to within 200 yards of the shoreline by now.
Next step, I checked the SMALL Racor/Honda fuel filter in the motor well and saw that it had a LOT of rust sediment in it. I drained that into the motor well and let it run out the drain hole (no tree hugers around). Re primed the filter and engines and they started for me, possibly averting a disaster or at least was able avert a long slow 13-14 mile ride home. I got back home and spent the afternoon sucking fuel out of the tank. The tank is a 115 gallon factory installed tank. The junk that had managed to plug up the filter continued to flow, but slower since I was using 1/4 hose on the filter, after draining the filter a couple of times, I would guesstimate that I had pulled 1/4 to 1/3 cup of junk out of the tank. Surprisingly, no water was present. I have had a very slight gas odor for some time in the hull, but no leaks.
My question is basically, IS IT TIME TO REPLACE THE 115 gallon tank? If so what is the easiest way to do this? There are 2 deck plates that will come out to give access. How is the tank fixed to the hull? Are they totally foamed in?
I do not need that big of a tank for my usage here in the islands. I am getting really good fuel economy with the new 225 Honda and would only use 20 gallons at most on a day of fishing. Should I go with another aluminum tank or go to a Moeller plastic tank, maybe 75 gallons?
There is a lot of questions here and I apologize for the length of the post. Gary

[Old'sCool]

Needed tank replacement would take inspection, pressure testing, etc. I would say welcome to the ethanol world.

[gss036]

I have never used ethanol in the tank. We still good gas here. The only stations here with alcohol in the gas is the AM/PM markets.
I wish there was an easy way to pressure test it in the boat. I have all the gas out that will come through the fuel pick up line.

[htillman]

You can try to clean it yourself, pay someone, or remove the covers and inspect the tank and then decide your course of action, you have a 20 year old tank. I have found some tanks to be foamed in - creating the problem, some neglected and some just no good. My advice, remove the deck and give it a thorough inspection.

[gss036]

Stopped by a shop that makes tanks for all the local boat builders. Got an estimate of about $500.00(ballpark)for a 65 gallon tank.
Should I put a larger tank back into the boat or go smaller. How would it hurt future selling price. Around here most boats this size run around 60 gallons.
Next project is going to be removing the deck plates and do a closer inspection and a look into the tank.

[salvagefirst]

RDS in fla built the original tanks in 1989,and they still have the diagrams for it. i replaced the 135 gal tank in my 89 23cc 3 years ago for 565 and shipping from Fla to eastern NC was 125. Les

[gss036]

I got into the tank today through the fuel sender hole and managed to get the rest of the gas out. I can see about 1/2 of the tank and it looks good inside, there is some junk on the bottom, but not rust and I was able to get a towel into the hole and swab out a lot of it. I think by tomorrow it will be completely dry with the gas evaporating. I am still pondering the next step. The tank looks to be foamed in so cannot see anything but the top.

[htillman]

At a minimum, block/plug all connections - use a bicycle pump with a gage installed through a cork in one of the blocked lines and see if the tank holds pressure. If it does, then it is your risk to use. If is does not then you have no choice replace.

[JohnB]

Gary,
I have a 1989 Sceptre, and when I pulled the tank out last year, this is what I found. It wasn't leaking, and 95% of it was fine, but there was deep pitting where the foam that held water was touching the gas tank. I don't know if it would of gone one or 10 years, but the pitting was more than 1/2 way through. As for the junk, you might want to remover your anti siphon valve, you really don't need it on an outboard as long as the lines are all above the top of the tank. Those will give you fits if you have junk in the tank. I put a 148 gallon tank in mine, but I run a lot of long distances.

[gss036]

I don't think there is an anti-siphon valve installed. There are 2 outlet/pickup tubes going into the tank. Both are within 1/4 inch or (probably) less of the bottom and nothing on the bottom of the tubes that I can see, they just look to be open. One of the tubes is plugged on top of the tank.
Where would the anti-siphon valve be located?
When I bought the boat new in 1989, there was a hose connected to the second connection and they just left it laying on the bottom of the hull with an open end. I removed it and put is a plug into the tank outlet.