odd shaped fuel cell

[ANDREW SMITH]

2005 Searay 180 Sport, the fuel guage reads 1/2 full when the fuel tank is way more than half full. The dealer does'nt understand why this matters to me but it does. I'd rather the guage reads the actual level of fuel in the cell. I think it may have something to do with the shape of the cell, it is "boot shaped", the top of the cell is tall but not much volume, and the bottom is much wider. The cell is odd shaped to fit around the aft jump seat. Can the sender be adjusted somehow, can the guage be re calibrated?? Your suggestions are appreciated.

 

[Chris1956]

Re: odd shaped fuel cell

They may be a way to add or remove resistance from the sender to achieve a nearly accurate guage reading. If the tank tapers (gets wider) from top to bottom, It may be a challenge to do so. All you EEs out there chime in with Ohm's law, and tell him the resistor value!<br /><br />Remember the resister value chant: Bad Boys R$%# Our Young Girls, But Violet G*&^% Willingly!

 

[jtexas]

Re: odd shaped fuel cell

Could you fabricate a curved sensor?<br /><br />ohm's law: isn't that something about an iguana, rabbit and vulture?

 

[Chris1956]

Re: odd shaped fuel cell

I had thought it was the iguana, rabbit and an emu. E = IR

 

[Richard Petersen]

Re: odd shaped fuel cell

You are stuck.

 

[18rabbit]

Re: odd shaped fuel cell

Can't we leave the rabbit out of this?<br /> <br /><br />A data display has no value if you can’t access the data. Your fuel gauge is your data display, it is not displaying the correct data ... it has no value!<br /><br />I’d start by calling Sea Ray and inquiring into their fuel tank design intent, and see if they intended for the fuel gauge to read correctly. I image so. Then it’s up to the Sea Ray, the dealer, whoever, to fix the problem so your 2005 boat works as intended.<br /><br />I hate “why” questions…they always hide an ulterior motive. When the dealer asks “why does it matter to you” he is hiding something else he doesn’t want you to know. Whenever I am asked a “why” question I respond with (a) “what is it you really want to know?” or (b) “rephrase your question without using the word ‘why’”. It’s amazing how people pause and think before asking again, and their question always changes dramatically.

 

[ANDREW SMITH]

Re: odd shaped fuel cell

Rabbit you are totally right. Searay should take care of this, but they are too slow to respond. I also have a temperature guage that reads 190F in normal operation, Searay is pointing at Mercruiser and they are pointing at Teleflex. Teleflex has sent new guages to Searay, but the problem is not fixed. Anyways, I have contacted Moeller Marine, who built the tank assembly, and Linda has promised to answer my question. Then I'll yell and scream at Searay with facts from the Moeller. Just wondering if this challenge is common out there at Iboats.

 

[Perfidiajoe]

Re: odd shaped fuel cell

On boats, fuel gauges are known to be inaccurate, unlike a car which is usually level, a boat pitches & rolls, so the fuel sloshes all over the tank, giving false readings. The problem with an irregular shaped tank, is that even at rest, with the fuel settled, (not rolling), a mechanical arm on a fuel sender will read the level in the tank, not the amount of fuel. In other words if most of the fuel is in the bottom half of the tank, the gauge at a half full reading, is showing you the fuel level is half way up the tank, not that you have half the capacity of the than in gallons. Boats are always compromises, trying to stick the most into the most unuseual shaped spaces, it's just the way it is. Most boaters don't rely on fuel guages except for a rough idea of how much fuel there is, If you want to have a good knowledge of the amount of fuel you have, or have used, you need a fuel flow meter. That being said, if you can get the dealer to make a change to make the gauge more useable for you, by all means persue it. Good Luck, Joe

 

[Perfidiajoe]

Re: odd shaped fuel cell

P.S. excuse the typo's As I am doing this in the dark, could't sleep & not wanting to disturb anyone else. Good Luck again, Joe

 

[cp]

Re: odd shaped fuel cell

As said above, the common fuel measurement system is simply a tank level indicator, with resistance varying uniformly per given increment of height. As long as the fuel gauge/meter face is marked in uniform increments, it's possible to have accurate readings only if the tank cross-section is uniform throughout its height.<br /><br />When a tank is not of uniform cross-section throughout its height, there are two ways to get accurate gauge readings:<br /><br />(1) Develop a programmed interface that will convert the linearly varying resistance into a non-linear output to the meter. The program must be custom designed to the shape of the tank. Obviously this ain't cheap and unless a manufacturer is going to use very many of the same tanks and is installing the programmed meter on a high end ($$$) yacht, they're not going to make that investment.<br /><br />(2) Mark the meter face non-linearly to conform with the actual amount of fuel in the tank. This is something you can do yourself, but having the meter re-faced will still cost $ if you can find someone to do it. What you do is put masking tape around the periphery of the meter, then ideally start with an empty tank. You have to know the total capacity of your tank, then you start filling it. When you've added 1/8 the capacity, you mark the tape accordingly where the meter indicates and so on until Full. Then you take the meter out, complete with tape markings on it, and take it to an instrument shop and have them re-mark the meter face in accordance with your tape markings. Now the meter may end up with the markings for full through 1/2 scrunched up in the clockwise third of the meter and the markings for 1/2 through empty spread out over the counter-clockwise two-thirds of the meter, but the indications will be more accurate than what you get now.<br /><br />Of course after doing all this, your meter will still only read accurately when the boat is not rocking and rolling. And that's why I think most manufacturers say the heck with it and just give you a 'ballpark' fuel measurement system.<br /><br />Out here, most guys know about how many GPH they burn and just keep track of hours rather than worry about the fuel meter reading. Of course no one runs for more than about 90% of fuel capacity so there's always a safety margin.<br /><br />I respect your desire to have accurate fuel meter readings, but as you can see, that's not simple to achieve. Good luck.

 

[18rabbit]

Re: odd shaped fuel cell

Good post, Pchonda. But the prob as posted is the tank reads 1/2 full even when it is full. So there is no way to know ‘about how much’ fuel is in the first 1/2 tank. As far as accuracy of fuel reading for any tank size/shape, there is a couple ways to do that, (1) dip stick, yes, they really work, and (2) sight glass, but it requires visual access to your fuel tank. Both methods are still very much in use except on recreational vessels. A sight glass is a must on a rec boat that does long range cruising.

 

[18rabbit]

Re: odd shaped fuel cell

Oops! Double post.

 

[ANDREW SMITH]

Re: odd shaped fuel cell

Thanks for all your suggestions. I did get a reply from moeller marine and they said Searay specified an inexpensive linear level sender for this model of boat. There is a more accurate, calibrated sender that Moeler offers, but Searay declined. The dealer was slow to respond because Seayray claimed a calibrated sender was not avialable. With this "smoking gun" information, I have asked my dealer to swap senders. Should be an interesting next couple of days. I'll keep you posted. Again thanks for your help.

 

[Perfidiajoe]

Re: odd shaped fuel cell

Again a sight glass is only going to show level not amount, & dip sticks do work, I use one to double check myself, but will only work if you have a straight shot down into the tank. Also I did not read the tank was full & the gauge read half, I read the tank was way more than half, & the gauge still read half. Does way more than half mean full? Also I'm not sure a sight glass is legal where does the gas go if the glass breaks? I've never seen a boat, long range or other wise, especially gas, with one. I'd check with the Coast Guard or the Ins. co. on that. Other than on outboard, & then only above deck, can you even have a clear plastic bowl on a fuel filter/water seperator. Joe

 

[cp]

Re: odd shaped fuel cell

A dip stick and sight glass will both work to show the level of the fuel in the tank. For tanks of non-uniform cross-section that will not provide an accurate indication of the amount of fuel remaining unless one has previously determined how many gallons correspond to each increment of height. Half height indication on a dipstick used in RebelRipper's tank will not equate to half the total gallons remaining.<br /><br />"Calibrating" or marking the dipstick or sightglass to show actual gallons present for a corresponding increment of height is equivalent to method (2) of my previous post.<br /><br />RebelRipper seems to have found a resolution to his problem since the tank manufacturer offers something akin to method (1) of my previous post. Hopefully his dealer will absorb the added cost for the calibrated sender, or RebelRipper is willing to pay for it, 'cause SeaRay has already made the decision to go with the cheaper one and is not likely IMHO to open itself up to claims by every boat owner for the more expensive one.<br /><br />RebelRipper - Please let us all know how this turns out.<br /><br />Good discussion all; hopefully everyone gained a little knowledge from this thread.

 

[Perfidiajoe]

Re: odd shaped fuel cell

Hopefully it will work out for RebelRipper, but most likely he will have to pay for it, either way, it will still never have the accuracy of some sort of flow meter. Depending on the cost of the parts, & the labor to install it, & who installs it,(check to see what this does to your gaurantee if you do this yourself), it might be cheaper to get a GPS or Depth finder, with fuel comsumption option. Navman makes them, & so does standard if you don't want a dedicated flow meter gauge. Good Luck, Joe

 

[Richard Petersen]

Re: odd shaped fuel cell

USCG regs. prohibit any openings on any side or the bottom. Bad leaks can occur. You have a problem.

 

[ANDREW SMITH]

Re: odd shaped fuel cell

The fuel tank is plastic (rotationally moulded poly something or other) so, I can see the fuel level just by opening the motor cover. So no sight gauge is required. The dealer could remove the blower vent and access the fuel level sender and replace it with the more expensive calibrated one. I am waitng to hear back from Moeller Marine if the attachments for each sender is identical, then the fix is not too cosly for anyone. I have Searay on my side in a funny sort of way. Every time my boat is serviced, Searay sends a customer satisfaction card to me in the mail. I fill it out with "problem not soved" and the dealer gets a nasty memo from Searay. Then the dealer must contact me to resolve the poor customer satisfaction. In this particular case, the dealer will be willing to spend a few dollars to keep their dealership with Searay. I'll keep you posted.

 

[jtexas]

Re: odd shaped fuel cell

I thinkthis <br />is what you're looking for, capacitance-type sensor measure volume regardless of tank shape.

 

[jtexas]

Re: odd shaped fuel cell