New guy with a fuel tank question.

[Jamie Z]

I was referred to this site by a member of ADVrider.com. I'm not new to water, but fairly new to powered boats.

Quick overview: My roommate has a 28-foot cabin cruiser. At the moment, I couldn't tell you the manufacturer. It's got a I/O drive, I think it's a Chevy 350 with a Volvo dual prop outdrive.

Anyway, he's had the boat for a few years, but for the past two or three seasons the boat has just sat in storage. I told him I'd pay half the slip if he'd put it in the water and let me use it. So a couple of weeks ago we put the boat in a marina. I'm very enthusiastic about using it, but we've had a couple of minor problems.

The first time we took it out, the boat ran perfectly for about an hour. Started right up, ran fine with no problems. Then fairly suddenly the engine sputtered and stalled. We were able to restart it, but then it would barely run above idle and we had to putt back to the marina.

We figured that the gas was old and that was the reason behind the poor running. The boat has a 106-gallon aluminum tank. The dash gauge showed about half full. The gas in the tank was about two years old. I don't know if any fuel stabilizer was used when the boat was put away.

I went back to the boat a week later. Again, the boat started and ran fine at first. I had it up at full speed for a bit, and then did a couple of small loops at half-throttle. No problems. Then it stalled and sputtered again.

I added 30-gallons of fuel at the marina. A guy at the marina suggested that I try a new fuel filter. I parked the boat, removed the fuel filter and bought a new one at a parts store up the road. It's a water-separating canister type filter.

I later disassembled the old filter, and to my eye it looked clean without any stains or rust.

With the new fuel filter installed, I ran the boat. Again, it would barely run above idle.

Today I went back and the first thing I did was take the cover off the fuel tank. I removed the sending unit on the tank and found this:

Though the tank is aluminum and appears to be in good shape, the sending unit is badly rusted with thick flakes of rust.

What I believe is happening is that the rust is clogging the screen on the fuel intake inside the tank. That's why it ran fine at first, but then sputtered. I also believe that the fuel in the tank is not bad or contaminated with water.

Is it possible to remove the rust from inside the tank? If it's just the sending unit which is rusting, then there isn't a lot of rust inside the tank, just enough to clog the fuel flow. I was thinking I could strain the fuel through a paint strainer and run the boat from an auxiliary tank temporarily until the main tank is empty, and then somehow clean out the rust from inside the tank.

Any suggestions where to go from here would be greatly appreciated. Go easy on me. I'm fairly mechanically inclined, but boats are a new thing to me (and my roommate).

Jamie

 

[Bifflefan]

Re: New guy with a fuel tank question.

The rust on the sender is probably from condensation in the tank. After 2 years (depending on the climate) there is probably water in the tank.
Your going to have to clean out the lines, the tank (as best you can) and the carb probably.
You may try adding gas drier, but...

Boats die of NON use more than use. They need to be properly preped to storage that long.

 

[rebars1]

Re: New guy with a fuel tank question.

There may be another fuel filter right where the fuel line connects to the carburator. You should check it also. You might check the water/fuel separator to see if it filled up with water.

 

[Paul Ryan]

Re: New guy with a fuel tank question.

The bottom one inch of the sender doesnt look to be rusted as bad as the rest of the unit. Looks like that was the fuel line during it's none use. I'm think your looking at a serious water issues. The water has probbly made it up the the carb bowl by now. I would keep that in mind. The rust issue??? Like yourself I'm mechanically inclined but am just now learning the tricks of the boating trade. Would a magnet get the rust out? Drain the tank as much as possiable then a magnet on a string or coat hanger to get the rust? maybe? I was in Lowes the other day and came across little "horse shoe" magnets. It was small enough that it would go through the sender hole. I'm not saying leave it in but for cleaning out. Take the hose off the tank and blow compressed air backward into tank to clean out the pick up.

 

[Silvertip]

Re: New guy with a fuel tank question.

The fitting that the fuel line connects to (just to the left of the two hose clamps in the picture) is an anti-siphon valve. Remove it and clean it, or better yet, replace it. It also is probably clogged with debris. With that much scale in the tank the pickup tube is probably getting clogged with debris. When you initially start out all the gunk is on the bottom of the tank. But as you run the boat the stuff gets stirred up and clogs the pickup. Not an easy task getting this mess cleaned up. I won't even offer suggestions as an empty fuel tank is a bigger danger than a full one. Leave that job to the pro's.

 

[ScottinAZ]

Re: New guy with a fuel tank question.

I would also jb weld a magnet to the outside of the tank when you get it mostly cleaned out. This will attract the smaller particles and help keep them out of the pickup

 

[PiratePast40]

Re: New guy with a fuel tank question.

Jamie,
When you're messing with the fuel system, keep a close eye on how things look before you take them apart. The suction hose attached to anti-syphion valve is a good example. It's double clamped as per Coast Guard regulations. If you remove it, remember to put it back the same way. Since you've got quite a bit of corrosion, take a good look at the ground and sending wires around the fuel system and make sure they're sound and secure. Keep taking pictures, it'll help tremendously when you get to putting things back together. "As found" isn't allways correct but it's a pretty good start.

 

[gss036]

Re: New guy with a fuel tank question.

I replaced my tank this past summer and the fuel outlet showing on the tank looks similar and mine did not have the anti-siphon installed, the new tank does and they are a pain as I found out today trying to remove some fuel for the mower. As stated above, you probably have the junk all through the system now, but if the old filter was a 10 micron water separator type, you may be ok if you can get clean fuel flowing. You didn't say what the old filter was or how it looked. Should have dumped it upside down in a clear qt jar.
I knew I had problems because I have a Racor filter and you can see all the junk in the tank. By running the boat you probably really stirred all the bottom up and now it is flowing with the fuel.
The bottom of the fuel pick up ( an aluminum tube) usually is about 1/4 to 3/8 inch off the bottom of the tank, some even may have a strainer and if it does, you can bet that it is clogged.

 

[Jamie Z]

Re: New guy with a fuel tank question.

Would a magnet get the rust out? Drain the tank as much as possiable then a magnet on a string or coat hanger to get the rust? maybe? I was in Lowes the other day and came across little "horse shoe" magnets. It was small enough that it would go through the sender hole. I'm not saying leave it in but for cleaning out. Take the hose off the tank and blow compressed air backward into tank to clean out the pick up.

We think a lot alike. The magnet idea was something I was considering. A long slender pole with a magnet on the end, spend an hour or so fishing around the bottom of the tank until nothing more sticks to the magnet. I don't know why that wouldn't work. And as you say, I figure a couple shots of compressed air should blow most everything out of the fuel pickup.

The fitting that the fuel line connects to (just to the left of the two hose clamps in the picture) is an anti-siphon valve. Remove it and clean it, or better yet, replace it. It also is probably clogged with debris.

Hm. This is a new one for me. What does the anti-siphon valve do? Is this a standard part sold at marine shops, or how do I "clean" it?

When you're messing with the fuel system, keep a close eye on how things look before you take them apart. The suction hose attached to anti-syphion valve is a good example. It's double clamped as per Coast Guard regulations. If you remove it, remember to put it back the same way.

Thanks. This is the kind of thing I'd never know. I was wondering why there were two clamps on that hose. Made for a real pain to remove, and I figured when I put them back, I'd use only one clamp. I didn't realize it was a Coast Guard rule.

Thanks for all the helpful replies! A quick update on what I've done since my initial post.

I brought a five-gallon gas can to the boat. Through the sending unit hole, I pumped gasoline from the fuel tank into the gas can. The gas from the tank looked clean. I ran it through a paint strainer, and there was nothing in it that I saw. (As an aside, is there a trick to removing the sending unit? I can't get it out of the tank. It's as if the sending unit is larger than the hole.) I added an inline filter and a short section of fuel line to the existing fuel line, and stuck the end of it into the gas can.

Boat ran perfectly. Took it out on the lake for more than an hour. Not even a sputter, except when the gas can went empty. Man, it goes through gas quickly.

As a test, I also had with me a five-gallon can of freshly purchased gas, and I ran the boat on that fuel. There seemed to be no performance difference between the fresh fuel and the fuel which was in the tank.

So now that I know the problem is with the fuel delivery system inside the tank, I have to figure out how to fix it.

Is there any reason simply blowing some air backwards through the pickup, and then fishing the rust out with a magnet wouldn't solve my troubles? As long as the tank isn't baffled, I should be able to reach the entire bottom of the tank, and with the magnet I should be able to collect any loose rust sitting on the bottom of the tank.

Jamie