Pesky Fuel Tank Issue.

[KRH1326]

I have a 62 gallon, below deck, aluminum gas tank.

When I started working on this project, I had discovered that the fuel fill line had begun to disintegrate, and was dumping rubberized particulate granules into the tank. After replacing the hose, I tried my best to "vacuum" the tank out, using an electric fuel pump and filter/ strainer set up, circulating back into tank.

Last season, was the first season that I had her in the water, on mooring. Among the other problems that arrised with such a project, I started to develope fuel blockage issues. The pick-up tube was getting constricted.

I repeated the "vacuum" deal and didn't have any further problems with it last season.

This season has become very problematic again. Two days in a row, this scenario has played out:

Start up normally on mooring, engine running great. Clear the harbor under 1000 rpm, 5 mph. Cruise about 3000 - 3500 rpm, 23-25 knts, for 20-30 minutes, to my good fluke spot. Set up and fish.
Once underway back to mooring, carb starves for fuel, stalls etc. Wait, sit, clear pick up tube, start up and proceed until engine starves again. Repeat if neccessary.

What I believe is happening is, that at rest on mooring, particulate is settled on tank bottom. Once out and running, drifting in chop, whatever, the particulate is getting suspended and jamming the pick up tube.

I have access to the forward part of tank, where fuel fill, vent and guage mounts to tank, and the rear part of tank where the pick up tube and line to filter is. I know that there are baffles in the tank, and that makes it very difficult to do my little vacuum trick.

I intend to try the vacuum setup (and no I do not mean the stupid shop vac thing that keeps finding its way into fuel tank posts) and my question for the forum is this:

Does anyone know of any other tip or trick to try while doing this?
Is there any kind of additive or 'detergent' that would help in this situation?
Any other input?

Just to clarify, The rig I use is an electric fuel pump with a filter and strainer that I try to manipulate around the bottom of the tank, while the pump is discharging back into the tank.

And also, I have gone through Don S. 's fuel system trouble shooting guide and do know that the clogging of the pick up tube is causing a blockage or restriction. Especially when it starves and dies, and I pop the first connection from the tank and can hear the hiss of vacuum air. It is not a case of clogged vent. Have clear passage there.

Thanks for any input.

 

[KRH1326]

Re: Pesky Fuel Tank Issue.

By popping the the first connection, I mean the first 3/8" hose barb at the tank pick up tube. The pick up tube is clogging. The fuel pump has been pulling through this hose, and the restriction has caused it to 'go dry' and created a small vacuum. Like if you were sucking on a straw, then put your finger over the end, you pull a vacuum.

The disintegrated hose was the fill hose. 1-1/4" hose from fuel fill on gunwhale down to tank. Not part of the engine side of fuel system, but common to the tank.

 

[KRH1326]

Re: Pesky Fuel Tank Issue.

Yeah, I did that with two inline glass screens (set up in paralel, just in case ) right at the tank. They do scuz up quick.

I don't remember if I completely removed the screen from the pick up. I think I did, but that was one of many inaugural problems I had, I just don't remember. I do recall the tube was disgusting and really old. I think it has to be original 1976.

I was looking in the Iboat store at what some new tanks cost, worst case scenario

You know what I didn't think of...

I may be able to outright replace the dip tube. They seem to have some universal stuff with 3/8" pick ups.

I am done for the day with this. Just nursing her back to mooring, and getting the kids ashore was enough excitment for me.

I will get to investigate further on Tuesday evening. Will pull and clean the two prescreens, and pull the dip tube, if it looks rough, I will just take it and try to replace it. Go from there.

If I remeber it correctly, it was a metallic tube that was pretty corroded, internally. May just be so junked up, most particles aren't even reaching the screens, just getting jammed up there.

Oh well, Tuesday will tell.

Thanks for the ideas.

 

[dingbat]

Re: Pesky Fuel Tank Issue.

This is one of those projects that you'll spend more time trying to cobble a fix than if you just bit the bullet and pulled the tank. On a boat that age, the tank is long overdue to be pulled and inspected anyhow.

Pull the tank and inspect for signs of corrosion in the area where the tank sits in the cradle and where the retaining mounts sit. If everything looks good, clean the tank and pull the pick-up. Most aluminum tanks I?ve dealt with have a welded pickup but you never know. Replace the anti-siphon valve on the top of the tank while you?re at it. While you have the tank out, replace the vent hose; replace the fuel lines running to the motor. Add a good quality, 10 um spin-on filter while you?re at it.

Guarantee your fuel problems will be over

 

[KRH1326]

Re: Pesky Fuel Tank Issue.

Yeah, that is true.

All is new. Fuel fill, fuel vent, anti-siphon and new lines out to the new sierra filt/ seperator.

My issue is this, if I cut up the deck to remove the tank, a new one is going back in.

There was a threaded fitting for the pickup, as I did have it out at one point. I kick myself now for not changing out that tube at the time. I only wish I could remember if I removed the screen, when I installed the glass inline screens.

Tuesday, Tuesday...tuesday