how to clean a fuel tank in your keel

[EuanMcKenzie]

I have an HR Rasmus with original MD21A still fitted.

It was running a bit rough but a good service sorted that. it still occasionally cuts out at inopportune moments usually when its bumpy but restarts immediately.

Conclusion is I have some bits in the fuel tank which is located directly under the engine in the keel

It has a draw pipe which i think has a open end that sits proud of the tank floor. There is a separate hand pump which draws from lower down in the tank and allows draw off of water and sludge.

I have already treated the fuel with Redex and gone through the pain of frequently changing filters as the sludge came through for most of last season and this. I also have a new pre filter fitter so the main filter doesn't sludge as quickly.

I've concluded that I have bits of something in the fuel tank that can be shaken up and occasionally are drawn over the end of the fuel pipe cutting the fuel flow.

When the engine stops the bit drops and hence its easily restarted. This also corresponds to the fact it doesn't happen at low revs

The only inspection hatch is full length along the tank and is an engine out job so not my preferred solution. I have considered getting the fuel polishing brigade in at great expense but:

- The fuel itself is not dirty
- and I am not sure if they will get out the bits

another thought was to fit another take off pipe in copper with numerous holes drilled in the end inch or two so that a single "bit" cannot stop the fuel flow. This would be awkward but doable into the metal at the front end of the tank inspection plate.

There are no traces of gelcoat in the coarse filter so i think the tank is ok I suspect there are bits that have been knocked into the filler point at some point or come in via the fuel

Has anyone solved this problem successfully before I invest in fuel polishing of clean fuel?

 

[wotayottie]

The HRs I have looked at have an external drain plug built into the keel. Is this only for water or is there one for the diesel tank?

Sounds as if you have the bug. Have you got any way of emptying the tank and flushing it? You could do a sort of fuel polishing exercise yourself pumping diesel round a circuit until you had the muck in suspension. Then pump the diesel into 5 gallon containers, treat with biocide and leave undisturbed to settle. You dont need filters taking this approach, just let the muck settle and decant off the clean diesel on the top.

I found that when I emptied the tank that flushing it with Gunk killed and helped remove the bug. Then washed out with water and detergent etc and finally left to dry.

Failing that, it isnt that difficult on most boats to slide the engine forwards which will giove good access to the tank and allow you to do a proper job

 

[robbieg]

This may help...

Just done this job to clean a 60 litre stainless steel tank which difficult impossible to remove from the boat. Considered fitting an access hatch but in the end did the job as follows.

Used a drill driven pump (£5 from Toolspot) and a couple of bits of 15mm hose to remove diesel to some 25lt Jerry can (bought from Towsure at £10 each). Then removed the sender unit and the filler hose which gave me one 20mm and one 30mm access hole and used a Snake scope-basically a waterproof web cam on a long fexible shaft (had one already since it has a number of uses on the boat but if you need to buy one about £40)-to check the condition of the tank through the sender unit hose.

Made a wand from 10mm copper pipe and squashed end nearly flat so it sprayed fuel at quite a force. Attached to 15mm pipe with some hose I had as a spacer and couple of hose clips to keep it together and then put 10 litres of clean diesel in tank. Sucking hose went in the filler hole and wand in the sender hole-easy to bend spray wand to shape and move about. Set the pump going and had a mini pressure washer that blasted the crud off the floor and walls. Sucked up the dirty diesel and repeat until clean. Use the Snake scope to check the tank from time to time and indentify remaining crud.

Built a hinging sqeegy tool attached to more copper pipe which I could put throught sender unit hole and then fix in position and use to scrape tank floor. Sucked up last bits with a Pela oil extractor and then wipe round with lint free cloth attached to another piece of copper pipe!

A final check with the snake scope to confirm the result- a shinny clean tank! Took about a day in total with sourcing kit, making up the wands,doing the job etc. My tank has no baffle which simplifies things but may still be possible to use above system with the baffled tank.

Hope this helps anyone who is considering this project.

 

[neil1967]

I'm about to build a simple polishing kit, which just comprises a filter, an electric pump and a length of 8mm copper tube. Intention is to put the copper tube through the inspection hatch and then get it right to the bottom of the tank to get any crud and water out. This would not be permanently installed device, just something to polish the diesel once or twice a year. With a suitably wide bore and coarse filter I suspect you could use something similar to remove the bits you think are stopping your fuel flow.

Neil

 

[EuanMcKenzie]

Rasmus has no external plug that i can see. I think that thought must have come later.

I definately don't have diesel bug as I think the tank is quite clean now as i haven't had a blocked filter in some months now. Also when you draw a sample from hand lift pump and let it settle it looks bright when held to the light.

My rough running was years of accumulated sludge etc that the redex did clear. Also bug would steadily block filters and wouldn't allow almost immediate restarting.

I definately think its bits of debris in the bottom of the tank so am reluctant to pump out the tank if I can avoid it. Boat is still in and i hadn't planned lifting it this winter

Like the idea of a recirculating filter. That could work. I have a removable lid for putting in the dip stick which is about 1" diameter and could enter the tank there with a hose.

I also have the spare water separator centrifugal prefilter unit which was changed out that I could butcher

What type of pump are you thinking of using? would a High flow electric fuel pump from a car work?

 

[sarabande]

Redex won't kill the diesel bugs. It improves the way that the diesel burns, and cleans pumps and injectors.

You need a proper bug killer, and then remove and polish the fuel back into a cleaned tank. DIY polishing is a very practical way to achieve 80% of that.

 

[neil1967]

I'm planning to use a spare pump that was previously fitted to a now-departed fischer panda generator. I don't know if it will have enough umpf or capacity, but I'll give it a go. If not there are plenty of car pumps available at up to £30-40 that should be man enough - or just go to a scrappy.

Neil

 

[KevinT1]

The keel drain plug on a Hallberg Rassy that is referred too earlier is to drain the remaining water out of the bilge / keel stub to prevent freezing ( the tank is a seperate alloy assembly ).

I had a similar problem - mainly due to water in the fuel and resulting diesel bug waste ( black jelly ) and the way that I resolved it was with a PELA Vacumm Oil extractor.

On my HR 36 the fuel takeoff is a square plate on the top of the tank, removing that gave me access and I could vacuum up the mess using the PELA and a long piece of copper pipe. Pumped out around 5 gallons of diesel and **** and the left it to stand for a few weeks in a large plastic barell - most of the sh t sank to the bottom and I could reuse the diesel.

Don't know if you can access your Rasmus tank in the same way - but even if you can get the draw off pipe out and wiggle the copper pipe / PELA around the bottom of the tank it should improve the situation.

best of luck

Kevin

 

[pvb]

The external keel plug referred to is only into the bilge, not the tank.

HR tend to use the Volvo Penta tank connection plate, which is a green circular casting on to which all the fuel pipes fit (see diagram below).

If you have one of these, remove the diesel flow and return pipes, undo the 5 screws and lift out the fuel pick-up pipe. This has a mesh gauze filter at the lower end, and this can get clogged with debris (see pic below).

If your engine installation is anything like mine, the suggestion that you might slide the engine out of the way isn't going to work. You could try fuel polishing using the access provided by taking off the tank connection plate, but it's likely your tank will have baffles which will obstruct the job. However, repeated circulation of the fuel will remove most of the rubbish eventually.

I wouldn't necessarily assume that you don't have any sort of bug in the tank, and would recommend you dose it anyway with a decent biocide as a precaution.

 

[EuanMcKenzie]

not arguing that redex doesn't kill bug but i don't think its bug that is jumping onto the end of the fuel pipe and causing it to stop flow then dropping back off again letting the engine restart. Also my filters arn't blocking any more.

I may find some in the bottom of my tank but its not what I think is causing the problem I described.

I was looking at car fuel pumps on ebay but note most don't have a very good lift capacity. what does look attractive is the pumps sold to pump volume from drums at circa 50 litres per minute. That would let me pump out of the dip stick hole and return it back round via filters through the deck fill connection.

50 litres / min may be too fast....

Pela pump looks really interesting - I see a deal online now for one so I may just go for it. Does it suck quite hard.

I am thinking about maybe 10mm copper pipe bent to a curve and flattened at the end to allow scraping the tank bottom while I hoover up gunk connected via hose to the PELA. Will it still prime do you think. The fact it is designed for oil makes me think it may and that it would be more robust. any thoughts?

 

[EuanMcKenzie]

you posted as I was typing

i have put a biocide in and will do again.

I think my HR is too old in that they hadn't got to fitting the plate you indicate on mine. It simply has a machined plate over the full length of the tank

The attached website (not my boat!) is a good read and has pictures of a tank opened up

http://www.lizardheadone.com/2010 Boat Projects.html

It definately has baffles which I hadn't thought through so there could be bug in one section I haven't detected - it gets harder.

Think I'll buy an oil extractor pump and make a start and see how I get on

will keep you posted

 

[KevinT1]

PVB's theory that the pickup pipe gauze is getting blocked sounds promising - getting that out and cleaing it would be a good start.

The PELA 6500 empties my engine oil with 7 or 8 pumps - it will not have any problem sucking up the muck from the bottom of your fuel tank. I wouldn't bother with anything fancy at the end - when I did it then I just used a straight piece of copper fuel pipe ( it was less likely to bend than the platsic pipe supplied with the PELA ).

The by product of the Diesel bug floats around in the diesel - but does settle over time - so if your boat hasn't moved for a few days then you will find it all at the bottom of the tank. And yes it is quite sticky, so attaches itself to the fuel pick up pipe, sender and tank walls.

 

[myquest]

I had a similar problem that turned out to be a gauze filter in the water separator that wasn't obvious until completely stripped down. Engine ran fine at lower revs but would stop after a period of fast running, then restart immediately.

 

[richardm47]

My Rasmus has a fuel guage sender, which is fitted at the (accessible) forward end of the fuel tank. Removing the sender will let you get quite a large pipe into the fuel tank. Then you can start vacuuming up the debris from the floor of the tank. Doesn't get you past the baffles though.

If you haven't got a sender fitted there then the fuel filler fitting on the tank would be the next best thing. In the past, I've had the filler pipe off and then put a wide flexible pipe down into the tank through the hole. Used that to Hoover out the bottom of the tank.

The Rasmus water tank is integrally glassed into the bilges just like the fuel tank. In my water tank, the inner surface coating is flaking off. Quite large flakes. If that is happening in your fuel tank, you'll need a fairly wide pipe to suck the flakes out.

I wonder if fitting a day tank would be another way around your problem.

 

[wotayottie]

What type of pump are you thinking of using? would a High flow electric fuel pump from a car work?

I used a pump like this mounted on a board and powered by a battery drill. Used garden hose to take all the diesel out of the boat tank into 5 gallon plastics, took them home, dosed the fuel with biocide and then left it to settle for a month or more. The I put it all bar the crud back in the boat and had no subsequent problems.

 

[EuanMcKenzie]

I ordered a PELA type oil pump off ebay last night

My tank doesn't have a sender but it does have a capped t piece with removable lid to allow the tank to be dipped. This preceded the nice to haves i think - mine is 1972


This will give me about a 1" hole to push a pipe down through.

Will let you know how i get on.

ref water tank. No flakes yet though and I've used a few chemicals to clean it up a bit - hopefully that is indication the tank is still sound.

Thats for all you're input.

Whats the favoured bug killer additive. I better do it again as well!

Euan

 

[lw395]

The Pela is great, but the standard suction tube will clog with diesel bug.
Replacing it with a 8mm bore hose with a 1/4 turn valve in it made life easier for me.
With the valve you can pump up a vacuum first, then aim the suction tube better.

 

[EuanMcKenzie]

update

The Pela pump works great - a good tip

Its found my black gunge in the bottom of my tank

Good news is that it looks like a thin layer

I put a length of 6mm copper pipe on the end of the suction hose and tried to "hoover" it up from the bottom of the tank

I sucked out ten litres of diesel in all with lots of slugs of black gunge coming through off an on as i pushed the copper pipe up and down on the tank bottom.

I then chucked in treatment and hope that will get the rest

Here's hoping.

I guess the fixed sump pump must stop slightly short of the tank bottom as I've never managed to pump this sort of gunk using it.

I guess my delusion is over I have contaminated diesel in my tank! Hopefully the startron I put in will kill and breakdown the rest

At least it was a sunny day and its nice just to get some air and spend time on the boat