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Banjo

Cleaning Inside of Fuel Tank

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I'm just preparing for when I put my 5K EFI engine into the KE30,  & want to have the "fuel system" all ready to go, once the engine is dropped in.

Luckily, I have a spare fuel tank, that came out of my KE55, when it went to "Rolla Heaven".

I'm preparing the tank, to have an in-tank high pressure pump, & a totally different fuel level sensor system, (hence additional opening at the other end of the tank top).

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The tank has been empty for several years, & has light rust on the inside of the tank, as seen in the photo above, through the filler opening.

Here is another photo taken through the top opening.

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I've never had the need to clean the rust off the inside of a fuel tank, previously, so Googled it, & found there are numerous "acidic" ways of cleaning, involving various acids, & home made mixtures.

However, there are descriptions of using an "electrolysis method", using the tank itself as the "cathode", & an anode of scrap ferrous metal suspended in a electrolytic solution, made up of water & bi-carbonate of soda.

Just wondering, if any of you have cleaned rust out of your tank before, & have a proven method, you employed, or would recommend.

Cheers Banjo

 

 

 

 

Edited by Banjo

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I had to resurrect an old tank when I removed my fuel cell for mod plating. I used a 2 step process...

1 I put a good few hand fulls of blue metal in the tank with some petrol and shuck the shit out of it. That removed any loose scale etc. 

Put a while bottle of CLR (Yes the old tv ad stuff) in the tank and let it sit in different positions over a few days. That left it sparkling inside!

Fyi looks like you're putting you're aftermarket level sensor in exactly the same place I did. 

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Usual one would be phosphoric acid, which turns the rust into black iron phosphate. Don't buy one with acrylic paint in, just plain H3PO4.

I've never worried about it, they don't rust when full of fuel so the only important part is stopping water getting in.  I don't know about using electrolysis on it, that will pit the steel and it may be quite thin already on the bottom if the tank has had water sitting in it in the past.

Either way, it should be interesting!

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Fyi looks like you're putting you're aftermarket level sensor in exactly the same place I did. 

What sort of fuel sender did you install, in your tank, Si ?  I've just about had those olde  rheostat type ones.  They are crude, wear away the resistance wire, until you get shorted turns. They are not very linear.  Either the fuel guage creaps down from the top, & races when it gets near the bottom, or visa versa.

I got hold of a vertical float type, where theoretically, nothing can go wrong, unless the float wears a hole in itself & sinks. (highly unlikely)

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It is 350mm long, & fits perfectly, in the Rolla  vertical tank, such that the bottom of the shaft, is proud of the bottom of the tank. by about 3mm, with a 10mm spacer mounting block at the top.

I can feed the signal into a micro, & linearize the output, by filling up the tank from empty with water initially; bit by bit, with a measured amount, & then work out the %  capacity of the tank for each switched output of the float.

I'll then switch a LED barograph, so that every bar has exactly the same "tank capacity %" between them.

My kids Toyota Echo has a barograph fuel guage, with just 8 bars.  This sensor has 14 off switched outputs, so I can have a fuel guage with 14 off LED bars.  That should be plenty.  Each bar would represent somewhere between 2.0 - 2.5 litres.

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 I don't know about using electrolysis on it, that will pit the steel and it may be quite thin already on the bottom if the tank has had water sitting in it in the past.

I've tapped to tank all over, & the bottom is showing no signs of being any thinner that the top of the tank.

P.S.  Si, after you cleaned your tank, did you coat the inside bare metal, with any proprietary product, for that purpose ?

Cheers Keith  

Edited by Banjo

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Hmmm where do i get one of those?

Still up in the air with the fuel system for my 11. IF I cut the tank for an "in-tank" it's nothing to add another hole for that.

I, fortunately have never had a tank that's needed any attention, soIcan't add anything to that sorry.

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Hi Stuart,

                I got that fuel level sensor off ebay.

https://www.ebay.com.au/itm/350mm-Marine-Water-Fuel-Sending-Unit-Boat-Truck-RV-Tank-Level-Sensor-0-190ohms/162421618044?epid=12013137635&hash=item25d115357c:g:f4oAAOSwi8VZTNBN

Think I got it for about AUD 52.00 from China.  Only took about 10 days.

Well made, in stainless steel, & comes complete with rubber flange gasket & 5mm screws.

The listings on ebay, depict them being available in a number of different lengths.

Cheers Banjo

Edited by Banjo

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On the weekend, I tried the electrolysis technique; not on the tank interior,  but on a very olde sickle, my wife picked up in a bunch of olde farm stuff, years ago.  It was very hard crusted rust, probably 50-60 years old at least.

I only stuck half of it in the water bath with some cheap washing soda added, (to make the liquid susceptible to electrical current flowing through it), so you can easily see the before & after results. 

The pics below indicate it works well, so the technique should not have any issues removing the "light" rust on the inside of  my KE30 fuel tank.

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Haven't made up my mind whether to have the tank interior sealed professionally, or do it myself, with one of the proprietary products available for that purpose.

Open to any suggestions or recommendations, regarding the sealing of the tanks inner surfaces.

Cheers Banjo

 

 

Edited by Banjo

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Ah- so the sender unit is one of these.

https://www.ebay.com.au/itm/150mm-Fuel-Gauge-Level-Sender-Sensor-Tank-Water-for-Car-Boat-Marine-240-33ohms/183225155455?hash=item2aa911ff7f:g:03IAAOSwKVtcmuZA

I'll have to stick a tape in the tank and see how deep a KE70 one is. The rheostat one I bought is hopeless, even if labelled 'for a KE70', it only has half the range needed.

A write-up and a wiring diagram when you're finished please!   I'd like to stick with the KE70 gauge, but the resistances are probably incompatible.

 

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I've rarely come across a fuel guage & sender unit, that are highly accurate & linear, over the whole range.

I've given up on them, although there are possible ways of linearising them.

The European standard for these fuel tank sender units is . . . 0 ohms when empty to 190 ohms when full

The American standard for these fuel tank sender units is . . . 240 ohms when empty to 30 ohms when full  (they just had to be different & reverse the range)

There are a few people on the internet complaining their guages are now indicating backwards, because they swapped sender units, & weren't aware of the complete difference.

Even the American standard is not adhered to by all the American motor manufacturers.  I found this list on a fuel tank repair company's website.

  • Ford up to 1986 - 73-10 Ohms
  • Ford 1987 & up - 16-158 Ohms
  • GM up to 1964 - 0-30 Ohms
  • GM 1965-1997 - 0-90 Ohms
  • GM 1998 & up - 40-250 Ohms
  • Mopar up to 1986 - 73-10 Ohms
  • AMC 1950-1977 - 73-10 Ohms
  • Autometer -240-33 Ohms is the most common however other ohm ranges are made
  • Classic Instruments - 240-33 Ohms (excluding vehicle specific gauge kits which use factory ohm range)
  • Dolphin - 0-90 Ohms
  • Dakota Digital - Programmable to work with most Ohm range senders
  • VDO - 10-180 Ohms

I did find a company in the USA called Speedway Motors, that makes a little interface module that will match any guage, to any standard sender, & even reverse the guage's movement, if necessary.

https://www.speedwaymotors.com/Speedway-Fuel-Level-Gauge-Sending-Unit-Interface-Module,66534.html

The beauty of this sender I have depicted above, is that it has no moving parts, in contact with the fuel.  The switches inside the enclosed & sealed S.S. tube appear to be fairly evenly spaced.  However, that still does not result in a linear guage movement, as the tank's horizontal cross sectional area can change, depending on the shape of the tank.

Now I found a Toyota Celica sender unit, some time back, that was almost the same design as the KE series sender units.  It measured about 200 ohms approximately at one end, so I installed it, in another tank previously, & it didn't work too badly.

Because this new "vertical" one I purchased, was about the same resistance as the Toyota one, I actually connected it up, to see how it read.  It worked pretty good, but was in reverse.

To use it, I would have had to cut the hole & mounting point in the "bottom" of the tank, and mount the sender upside down, for it to read correctly.  That wasn't going to happen.

The linearising process is slow process, pouring small measured units of water into the tank, but it should work well.  Will show you the results, when I have completed it, in the next day of so.  Although, I have decided to use a LED bargraph display, it should be possible to control the current to the original thermal operated meter movement, to linearise its response.

P.S.   If you have a fuel guage that won't get to full, there is a quick way, you can partially fix this.  The fuel & temp guages in the KE series, do not operate on 12volts. They are supplied by either 7 - 8 Vdc from a little regulator, (on the rear of the dash console), that keeps the guages steady, irrespective of the cars 12V voltage system, which can vary over 11-14 Vdc nominally. However if your guage can't get to full, when the tank is full, you may be able to get it to read higher, by feeding the guages from 12 volts, rather than the regulators 7-8Vdc.  I did this once for about a year, in one Rolla, & it worked quite well.

Cheers Banjo

 

Edited by Banjo

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I made a little stand up for the tank, last night, so the tank sits vertically, whilst I do the linearising procedure, for the fuel guage sender.

It can then sit it near the "test engine" on its stand, whilst I play with the EFI setup, before mounting the tank in the KE30.

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I want to put a submergible hi pressure EFI pump inside the tank, but haven't chosen one as yet.

My criteria are, that it must . . . .

Be a commonly available unit.

Be very reliable.

Be quiet.

Fit through the existing 45mm dia. hole in the top of the tank.  (don't really want to open the tank up, if at all possible)

Have a "sock" type inlet filter, attached to the bottom of the pump.

Something like this . . . .

image.png.b6ee1228d88c2e44d8c6b597e984b7ab.png

Any suggestions, or recommendations of pumps you've used successfully, in similar situations ?

Cheers Banjo

Edited by Banjo

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Well I finally found an in-tank EFI fuel pump, that is "slim enough", to fit down through the hole in the top of the KE fuel tank. The hole opening in the tank is 45mm; & the pump I received today,  is just 38mm in dia.

https://www.ebay.com.au/itm/38mm-Fuel-Pump-for-Toyota-Rav4-Corolla-Camry-Echo-Hilux-Prado-Subaru-Impreza/332581529188

What's more, it used on several late model Toyota vehicles, like the Echo & Corolla.

DSC01477sm.jpg.e326e23ae9a53e883b698bfdba5ad4f0.jpg

All I have to do is now plumb it all up !  It comes with all the fittings & filters etc, so is good value.

Cheers Banjo

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Update on this little project, which was interrupted by work commitments.

The circuit I designed around a microprocessor, plus one of those multi_LED stack barograph thingies worked well. I set it up on my tank test stand, & slowly added, 1 litre at a time of water down the tank inlet, with a plastic funnel attached.  1 litre plastic jug, with markings, (courtesy of wife’s kitchen cooking cupboard), provided accuracy.

I also replaced the normal fuel pickup assembly, & fitted a bit of  fuel hose, so I could blow down it, after emptying each 1 litre jug of water. Once the water level reaches the tip of the pickup pipe, you can hear the bubbles.  When it covers the pickup point, you know, because you can suck on the tube, & the water comes up.

Well, that revealed my first lesson. The bottom two (2) switches of the fuel level sensor, had already illuminated the first two LEDs, before the water level was over the bottom tip of the pickup tube. So that limited me to only using 12 off the switches in the fuel level sensor, with 14 off switches.

It also revealed that there are approximately 8-10 litres of fuel, left in the bottom of the tank, when you finally splutter & pull over on the side of the road, when the engine runs out of petrol.

Initial thought was . . . I will have to get hold of a shorter level sensor. (There was a 250 mm one listed on ebay, identical to the 350mm I have.

So I continued to add 1 litre at a time, & the LEDs progressively lit up, until the very last LED was illuminated. By this time I had filled the tank with approximately 48 litres of water. However, the tank was not full, as when I removed the fuel pick up assembly, I could see the level of the water, was below the top of the tank.  I continued to add my 1 litre jugs of water, & can report that the tank was full, with a total of 55 litres of water.

That seemed to add up, as when I fill my Rolla, it always takes a bout 38-40 litres, (depending how close to dead empty it is)

So 55 litres less the 10 you can’t use, is 45 litres. That means when I fill up, there is still about 5-7 litres left, before the engine would have stopped.

So I’ve got a fuel sender, with 14 off level switches, the bottom two of which can’t be used, & the top two trigger/switch, before the tank is full.

It then occurred to me, that if I retained the level sensor I have, but lifted it up vertically, it may solve the issue.

All it involved was to build a little plastic mounting block for the sensor, sited on the top of the tank, that would lift it up vertically, so hopefully, at least one of the bottom switches could be used, & that the top two, could indicate right up to full tank.

So back to wife’s kitchen cupboard to cut three (3) x 100mm square pieces of plastic, out of her bread-board, which I then drilled & cut, using the level sensor top plate as a template.

Pictures below, show what it finished up looking like, when mounted to the tank.

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So tomorrow, will be the big test, when I borrow my wife's 1 litre jug again, & we will see if this theory, works out in practice.

Cheers Banjo

P.S.  Sorry, got to rush now, & get to the shop, before it closes, & grab a new bread board, before my wife returns home.

 

Edited by Banjo

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Lol!  I hope you bought a nice chunky wooden one, those plastic ones are rubbish! 

Did you factor in the arm of the stock sender unit, it sits away from the hole and measures depth at a different place. Maybe they read the last 10litres.

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Maybe they read the last 10litres.

No, if the standard fuel sender unit, read the last 10 litres, then the float would have to be below the bottom end of the fuel pick up point, & therefore you would run out of petrol, before the guage actually got to minimum.

My 1974 KE30 has a separate fuel guage sender unit at the end of the tank.  The tank I am using is out of my deceased KE55 Coupe.  It has the sender unit, in the centre,  as part & parcel of the pickup  point assembly.  I  have had that unit out of the tank, & when the float is hanging at minimum, the float is slightly higher than the bottom of the pickup point, as it should be.

P.S. Already got a "nice chunky wooden one".   It is my cheese board.  Luckily, my wife drives a Corolla also, albeit, a bit younger than my  KE30.

Cheers Banjo  

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