# Clean Fuel in-hull fuel tank



## Snelly (Oct 3, 2007)

Hi all,

I need to get my in-hull fuel tank cleaned and the hoses to the engine flushed.

I've had periodic (getting worse) problems with the outlet hose getting blocked while running.

I emptied the tank myself but I only have the sender unit hole for access and can't clean it properly. Fuel back in and same problem.

So what I need is for someone to clean it all out properly and hopefully re-claim the fuel.

The tank is 116 gallons and the deck can be removed. I probably should replace the fill and vent hoses as well.

The boat is a 1986 23' Sea Ox.

Any suggestions?


----------



## Chapman5011 (Mar 7, 2013)

What is clogging it. Where is it clogging


----------



## JT Powell (Jun 20, 2012)

I'm not going to say your tank shouldn't be cleaned, but this is most likely your problem if you've been running ethanol fuel. You could probably replace all the lines and be good.


----------



## Fielro (Jun 4, 2012)

Ethanol is probably your culprit


----------



## Snelly (Oct 3, 2007)

Thanks for the replies.

I've replaced all the fuel hoses (from the tank up to the engine) and the fuel/water separator.

When it clogs, I remove the inlet to the fuel/water separator and blow back down the pipe into the fuel tank - that clears the blockage.

I've always used treatment for the fuel (Ethanol) and when I drained the tank and had a few samples set in glass jars and no evidence of separation of the fuel - not saying there wasn't any though.


I'm not sure what is doing it. My problem seems to happen mostly when I've been trolling at slow speed for a while and then open up the throttle to go fast.

It's like something gets drawn to the feed pipe in the tank and then when a sudden gulp of fuel is demanded it gets suck into the feed pipe and blocks it.


----------



## JT Powell (Jun 20, 2012)

Can you feel a blockage when you blow the line back, I'm asking because it sounds like its a vent line blockage as your trolling your slowly creating a vacuum on the tank.


----------



## Snelly (Oct 3, 2007)

JT Powell said:


> Can you feel a blockage when you blow the line back, I'm asking because it sounds like its a vent line blockage as your trolling your slowly creating a vacuum on the tank.



Difficult to say.

I would say yes, but your suggestion might be correct. The resistance I feel could be the hose popping back out...


----------



## JT Powell (Jun 20, 2012)

This ones easy to diagnose, take it out and see if you can recreate the problem when it happens open the gas cap and see if it regains power.


----------



## floater1 (Oct 31, 2007)

On the pickup tube some of the tubes are 2 piece with a screen in the middle and most have a checkball nipple to prevent backflow and both give trouble in just short time I would reccomend removing the pickup tube and see if the problem lies in the tube it easy and like 35 for new pickup tube and nipple


----------



## Chapman5011 (Mar 7, 2013)

I have had a problem like this at times. Fuel would not pump into the bubble. I kept replacing pump bubbles. 
I would disconnect the fuel line from the front of the bubble, then blow toward the fuel tank. Then pump till fuel came out and then hooked bubble back up. It did it a few different times. 
The fuel pump bubble (2-stroke) would have the little orange plastic looking pieces In it which I feel was clogging the bubble from pumping correctly. 
Also when I change my fuel filters twice a year now they are slap full of the dried up orange plastic looking stuff. I've been told that is ethanol. 
You could shake the pump bubble and hear the pieces rattling inside.
Cut open your fuel filter an look at what's I side it next time you change out fuel filters. You might be amazed. I know I was a few weeks ago when I did it.
Has not happened in about 500 to 600 miles. So maybe I figured out what the problem was


----------



## DAWGONIT (Jan 16, 2009)

Call Nick Moore. They polished my fuel tanks and gave everything a once over.
They're mobile and will come to you.

Not associated with them, but a VERY satisfied customer.

http://www.dieseldone.com/ 850.456.9070


----------



## Snelly (Oct 3, 2007)

JT Powell said:


> This ones easy to diagnose, take it out and see if you can recreate the problem when it happens open the gas cap and see if it regains power.


A good simple idea...now why didn't I think of that 


I'll give a go. I think the vent hoses may the issue, the boat is 1986 and I'm sure they have never been replaced.

Where's the best place to get new hoses?


----------



## X-Shark (Oct 3, 2007)

Rubber & Specialties or Rubber & Gasket.


----------



## murfpcola (Aug 28, 2012)

Check the barb fitting that the fuel line hooks to on the pickup. Most have a check valve that go bad and will cause the bulb to suck flat. If opening the fill cap does not solve your problem then chec the check valve.


----------



## X-Shark (Oct 3, 2007)

murfpcola said:


> Check the barb fitting that the fuel line hooks to on the pickup. Most have a check valve that go bad and will cause the bulb to suck flat. If opening the fill cap does not solve your problem then chec the check valve.


Then....Remove the fitting.....With a small pin punch....knock the ball out of the fitting. Then reinstall the fitting.

Do not use Teflon tape on any fuel fittings.

Use this:


----------



## Snelly (Oct 3, 2007)

*Update - still a problem*

Thanks for all the replies. I suddenly got sent overseas and have just got back and checked it out.

The primer bulb stays good.
The tank fuel outlet does not have a check valve.
I have now replaced the breather lines and the fill hose, and have previously replaced all the fuel hoses.
I've changed the fuel/water separator and even put in a glass bulb type.
I inspected what I could of the tank using a borescope, scanning the liquid surface and the bottom revealed nothing. It is a 116 gallon tank, so I couldn't really see every part clearly.

I ran the boat and got the same problem, when it was messing about I removed the gas filler and no change.

The only thing that seems to cure it is to remove the feed pipe from the tank and blow back into the tank.

My guess is that I still have an obstruction problem in the tank, so my next job is to find someone to empty, clean and refill the fuel tank, hopefully cleaning and re-using the fuel.

Thanks,
Chris


----------



## Play'N Hooky Too (Sep 29, 2007)

If you think it is a problem with dirty fuel, Perdido Marine Services has a mobile filtration system that they can use to clean the tanks without removing them from the boat. They are located in Pensacola.

(850) 912-4551
Ask for Leroy.


----------



## floater1 (Oct 31, 2007)

Snelly said:


> Thanks for all the replies. I suddenly got sent overseas and have just got back and checked it out.
> 
> The primer bulb stays good.
> The tank fuel outlet does not have a check valve.
> ...


Take the pickup tube back out and make sure it's not a 2 piece with a screen. I went through this with my boat before finding out there was a screen in the pickup tube

Sent from my SAMSUNG-SGH-I537 using Forum Runner


----------



## Sarghah (Jul 31, 2014)

Where is it clogging


----------



## Snelly (Oct 3, 2007)

Just had the tank cleaned out by Leroy and Keith at Perdido Marine - top guys and they did a fantastic job, going well above and beyond!!

We didn't find much debris in the tank, not even a thimble full and no water.
I had previously cleaned the tank and used Ethanol free fuel ever since.

Unfortunately, the problem is still there.
All fuel and breather lines replaced and blown through.
Tank cleaned
fuel water separator replaced
engine fuel filter replaced
tank pickup tube blown through
fuel pump replaced

I have a real problem with acceleration, the engine bogging down, almost like it is being choked.

If I 'pump' the throttle up and down whilst trying to accelerate I can sometimes get it to accelerate up to plane. Sometimes it is fine.
Once on plane the engine normally runs smooth but sometimes it slowly dies.

Whatever the issue is, it's erratic and I don't know where to go now.
Any other ideas???


----------



## Snelly (Oct 3, 2007)

Sarghah said:


> Where is it clogging


It seems that when I get the problem, if I remove the feed pipe from the tank to the fuel/water separator and blow back into the tank, the problem goes away for a while.

I've just used a compressor to blow back down into the tank (with a net on the end to catch anything) and had the fuel/tank cleaned - that didn't fix it...


----------



## Snelly (Oct 3, 2007)

floater said:


> Take the pickup tube back out and make sure it's not a 2 piece with a screen. I went through this with my boat before finding out there was a screen in the pickup tube
> 
> Sent from my SAMSUNG-SGH-I537 using Forum Runner


The pickup tube is welded into the tank, so I can't do that :-(


----------



## rustybucket (Aug 18, 2011)

Pull your pickup tube and replace the in-tank tube with a tube that DOES NOT have a pickup screen on it.

This will allow the debris to pass through the line and hopefully get caught in your water separator filter.


----------



## Snelly (Oct 3, 2007)

rustybucket said:


> Pull your pickup tube and replace the in-tank tube with a tube that DOES NOT have a pickup screen on it.
> 
> This will allow the debris to pass through the line and hopefully get caught in your water separator filter.


any tips on how to remove the welded tube?


----------



## Ocean Master (May 20, 2008)

You will have to add a new pick up assembly and cap the original one IF that is the problem.

This is if the tank stays in the boat..


----------



## floater1 (Oct 31, 2007)

Snelly said:


> The pickup tube is welded into the tank, so I can't do that :-(


If it is welded in there should be another one welded I next to it can u get a pic of the pickup tube

Sent from my SAMSUNG-SGH-I537 using Forum Runner


----------



## Snelly (Oct 3, 2007)

floater said:


> If it is welded in there should be another one welded I next to it can u get a pic of the pickup tube
> 
> Sent from my SAMSUNG-SGH-I537 using Forum Runner


There's not much room in the access panel area, see pics...
I've got a manual brass shutoff valve on the tank outlet.


----------

