I'd like to add a fuel gauge to my H31, but am on a shoestring budget. My experience with auto fuel gauge senders is that they just read the angle of the float arm, which goes through a winding and the variable current is sent to the gauge. Since the gauges only measure fuel level, not remaining gallons, I'm guessing that the length of the arm is designed in relation to the depth of the tank. If I am right so far, I theorize that I could go to a wrecking yard and find a sender and gauge from a car with a tank about the same depth as mine. Provided I could find a way to mount the sender in the tank, it should give me a fair estimate of the fuel level [course boats rock considerably more than cars and on more planes, so one could look to the gauge only in relatively calm seas and not when healing. Still, that seems better than a prayer and a dipstick].
What's wrong with my fuel gauge theory?
- Thread starter wufibugs
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Nothing is wrong with your theory. It is useful independent of the accuracy. I usually add fuel in 5 gallon doses and have built up a record of how much the level rises from and to for a filling. By now I figure I know exactly where I am and also where I am going to be for x amount of running hours, even though the tank is an odd shape and the read out would not be linear with level anyway. Without the indication you wouldn't know anything.
For what it is worth I have used 275 gallons for 452 running hours on my 3qm30 in 8 years.
For what it is worth I have used 275 gallons for 452 running hours on my 3qm30 in 8 years.
Can you salvage one from a boat that has been destroyed? I don't "trust" my gauge, like Jonb, I use it as an indication and never let my tank get below a 1/4.
just get your self a WEMA sending unit and be done with it..they come with the mounting holes in a standard pattern...when you contact them they usually tell you about there EBAY store so you can buy it cheaper....if they dont tell you about EBAY then ask them the company name is BESTFAB when doing an on line search...
hope this helps....
regards
woody
hope this helps....
regards
woody
The best way to make sure your gauge is accurate is to know:
1- The capacity of your tank
2- Empty it.
3- Now fill it in fourths and mark each fourth on the fuel gauge with a Sharpie.....
Marine tanks are often not square or rectangular and thus it is impossible for a gauge to be accurate.
So for a 20 galloing tank drain it, then fill it in 5 gallon increments marking the gauge glass at each 5 gallon fill. While not "pretty" it works very well....
You can buy a marine sender and gauge for under $60.00 if you shop around..... Another easy way is to simply keep track of fuel use against engine hours...
1- The capacity of your tank
2- Empty it.
3- Now fill it in fourths and mark each fourth on the fuel gauge with a Sharpie.....
Marine tanks are often not square or rectangular and thus it is impossible for a gauge to be accurate.
So for a 20 galloing tank drain it, then fill it in 5 gallon increments marking the gauge glass at each 5 gallon fill. While not "pretty" it works very well....
You can buy a marine sender and gauge for under $60.00 if you shop around..... Another easy way is to simply keep track of fuel use against engine hours...
Are you serious? We're talking about less than $25 for a marine fuel level sender. Surely you would spend more on gas searching around for something that works, plus your time, plus the risk that it won't work, after all, etc., etc. I believe in the virtue of frugality, but in the extreme it is wasteful.
http://www.wholesalemarine.com/moeller-marine-electric-fuel-sending-units.html?gclid=CLjNtbio6bkCFcOh4AodWXcA6Q
Just google "marine fuel gauge sender."
http://www.wholesalemarine.com/moeller-marine-electric-fuel-sending-units.html?gclid=CLjNtbio6bkCFcOh4AodWXcA6Q
Just google "marine fuel gauge sender."
The WEMA tank gauges do not have an arm like this. They have a rubber float at rides up/down on a stainless shaft. I have had one of these units in our tank for about 3 years and it work as well as can be expected.
Before you do anything, I would be very careful cutting into one of these poly tanks and then trying to seal it. There are some solutions that work well, but probably not if you are on a tight budget.
You may want to just keep a log of the operating hours which can also work well.
Before you do anything, I would be very careful cutting into one of these poly tanks and then trying to seal it. There are some solutions that work well, but probably not if you are on a tight budget.
You may want to just keep a log of the operating hours which can also work well.
I still believe the "best" fuel guage is a No. 2 Pencil and a spiral note pad. You should know the fuel consumption rate of your engine at various rpms and just keep track of the hours it is running. Start with a full tank and you'll always know how much fuel is left in the tank. The worst thing that can happen is you may have to sharpen the pencil now and then.
I agree with Warren. When I first got my boat I was obsessive about instrumentation, and even added an oil pressure gauge where there once was none. My gauges have failed one by one, a bitter disappointment for fairly new gauges; but I have found I'm happier without them. I know my tank is 32 gallons, I fill it up occasionally, and I know what my fuel consumption is. I check when I think I'm just above 1/2 tank. For a while I used a stick in the hole where the sender is. Now I just use engine hours.
The only risk with this is that there are engine faults that can cause increased fuel consumption; hence checking at the halfway point.
I would rather have a sight-glass than an electric gauge.
The only risk with this is that there are engine faults that can cause increased fuel consumption; hence checking at the halfway point.
I would rather have a sight-glass than an electric gauge.
I just assumed sending units would be costly, but the comments sent me to Ebay for a price check. Indeed there are some at $20. So even though I do love rooting around in wrecking yards [if there were a pic-ur-own-parts boat salvage yard anywhere around, I'd probably work there for free], it doesn't pay to salvage an auto sending unit.
The fuel log idea has merit though it conjures up long repressed memories of the futility of trying to cajole offspring to make good on the blood oaths they took when paid in advance to do certain chores. My adult boys, to the extent anyone afflicted with my genetic material can be called adult, have begun short forays into the bay on Windmistress. The fact that they are both over 30 with families of their own does not even slightly dissuade me from calling them to make sure seacocks are closed. Fuel log? Right. I suppose I could rely on the engine hour meter since there is very little worry that they might actually have sprung for some diesel.
A fuel gauge seemed a good backup system, though I will have to rethink that in light of Steve's sobering comment about installation and sealing the tank.
The fuel log idea has merit though it conjures up long repressed memories of the futility of trying to cajole offspring to make good on the blood oaths they took when paid in advance to do certain chores. My adult boys, to the extent anyone afflicted with my genetic material can be called adult, have begun short forays into the bay on Windmistress. The fact that they are both over 30 with families of their own does not even slightly dissuade me from calling them to make sure seacocks are closed. Fuel log? Right. I suppose I could rely on the engine hour meter since there is very little worry that they might actually have sprung for some diesel.
A fuel gauge seemed a good backup system, though I will have to rethink that in light of Steve's sobering comment about installation and sealing the tank.
my fuel tank i s a crappy one, as it is for a car..but it does have a transparent inspection plate, so i could see how much fuel was at the bottom of tank just befoore i ran out, so my repair friend made a dowel calibrated for shape of tank.
most fuelk gauges in boats donot work. use a stick in tank..works better and is cheaper. as the tank sukks bad, we will rerplace it some where and some how during these repairs...or heavily modify and change water tankage to fuel and fuel to water.
most fuelk gauges in boats donot work. use a stick in tank..works better and is cheaper. as the tank sukks bad, we will rerplace it some where and some how during these repairs...or heavily modify and change water tankage to fuel and fuel to water.
The device you need to have a good chance to seal your tank is a Seabuilt Access Plate. ( http://www.seabuilt.com/6plates.php )
The WEMA stuff is reasonably priced. ( http://www.wemausa.com/sensors/coverSensors.shtml ) The gauge is about $27 and the sensor is about $40.
The WEMA stuff is reasonably priced. ( http://www.wemausa.com/sensors/coverSensors.shtml ) The gauge is about $27 and the sensor is about $40.
I wouldn't think you would find one of those "old style" sending units at a scrap yard anyway. I think most autos use an integrated sending unit along with the fuel pump.
And the unit that has been shown here, if I went to the trouble of putting one in, it SURE would be a new one. They're not very long lived apparatuses in my experience. And the first one or two you ever fool with takes some thinking, the aforementioned angles etc. And those five bolt holes are not symmetrical either. I has to be oriented in a particular direction. Outside of that, they're pretty durn simple..
And the unit that has been shown here, if I went to the trouble of putting one in, it SURE would be a new one. They're not very long lived apparatuses in my experience. And the first one or two you ever fool with takes some thinking, the aforementioned angles etc. And those five bolt holes are not symmetrical either. I has to be oriented in a particular direction. Outside of that, they're pretty durn simple..
The type of fuel sender you are referring to here does not measure "angles"
or send variable current. The winding is actually a stepped resistor that changes the voltage as the float arm moves. The gauge reacts to the voltage. There are different ways to design it but its like 12V might read FULL on the gauge and say 3 volts might read EMPTY.
I'm sick with a nasty cold and have nothing better to do right now so I'm just sayin'.....
Good luck and Happy Sails
In the US most marine senders and gauges are sending/reading a range of resistance from 33 Ohms to 240 Ohms...
Top, that's kind of how I thought it worked, I just did not know how to express it correctly. BTW, one of my coworkers had what Kaiser kept telling her was a "nasty cold". After 3 weeks they have now decided it's pneumonia. Be careful.
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