See full version: Most reliable fuel sending unit for boat
In this photo we are looking at a Moeller, used to be Tempo, mechanical fuel sender with an electronic conversion capsule installed. If you look closely you will notice the red pointer of the mechanical gauge pointing to 9:00 or approximately 1/4 of a tank. here
The fuel sender, for the typical US standard used in a marine application, is a simple device that presents a resistance reading to the gauge with which it is paired. For US fuel gauges, from the likes of Stewart Warner, Faria, Vee-Three, Moeller, Teleflex, Tempo, Westerbeke, Universal etc. this reading is 33Ω - 240Ω.
#1 El Cheapo Type - The one in this photo is the style I refer to as the "El Cheapo".. They are inexpensive and last about as long as the flavor of the gum in a pack of baseball cards. I replace this style sender about 10:1 over the other types mentioned below.. If you have one like this, and it has failed, look into the other types shown in this article.
Here is why you need to test this sender properly. Note the negative lead for the DVM is connected directly to the flange and we have a OL reading on the DVM. Don't mistakenly test this type of unit by connecting to the flange. You need to test across the two wires coming out of the top of the sender. Like the conversion capsule this sender is isolated from the tank. [links]
To test the conversion electric capsule simply connect the DVM to the two leads coming out of it. Polarity is not important here. This is a perfectly acceptable reading for this sender and it is working correctly. [links]
Is your fuel gauge inaccurate? Is it no longer working at all? This is a common problem on older boats, but is easy to fix. The first step is to determine whether the problem is with the gauge or the sending unit. The test for this is straightforward. First, check that the gauge is receiving 12 volts of power. Turn on the engine’s ignition and probe with a multimeter between the ground and the positive terminal on the back of the gauge; it should be marked with a “+” or an “I.” If there is no voltage then the fault is in the ignition circuit—and the gauge is probably good. If there are 12 volts at the gauge, either the sender, the gauge or its wiring is the culprit, so you need to proceed to the next step.
The sending wire will come off a post in the center of the flange. There may also be a ground wire coming off a second post at the edge of the flange. Both wires lead to the back of the fuel gauge. Turn off the power running to the boat’s systems before you disconnect any wires. Then disconnect both the sending wire and ground wire on the old sending unit. Note that if the gauge is grounded directly to a tab on the tank, there may be no ground wire. Remove the screws that hold the sending unit to the tank and take it out. [links]
Often a problem occurs when the sending unit’s floating arm becomes inoperative. On older units the floats may be made of cork. Over time these floats can lose buoyancy or even sink altogether, causing the fuel gauge to indicate that the tank is constantly empty. more
The Method:Some of the products tested were designed for gas, some for diesel and some for either. We only tested products with their intended fuel. To deliver the fuel, we stuck to the same method in test after test. We filled the tank at full speed until the nozzle clicked off. We did not top off. We felt that this method best represented the practices of the majority of boaters, and it allowed us to provide the same fuel delivery speed each time.
Cars utilize a pressurized system to deliver fuel directly to engine injectors. This is done under high pressure delivered by a pump within the fuel tank to assure peak performance and economy. This type of system also does not permit air or fuel to escape from the tank during operation and does not have a vent to relieve pressure. Cars also have a carbon canister to control vapor emissions. [links]
Couple that with the law. Under federal law, you are required to report a fuel or oil spill, no matter how small, if it is enough to cause a sheen on the surface of the water. And by creating a sheen, you are breaking a law and opening yourself up to fines that can go into five digits. While you want to get rid of the sheen, it’s also illegal to use a couple of squirts of dishwashing detergent on the water’s surface. Add this all up, and you can see how the nature of boat fuel tanks and the law don’t exactly make compatible bed fellows.
As the world’s leading designer and manufacturer of liquid level senders, KUS has extensive experience working with designers and engineers from industry OEMs, and understands the quality they have come to expect. Designed to suit the rigorous demands of the automotive, trucking, marine, industrial, agriculture and power generation industries, KUS products are known for their reliability, accuracy and durability.
The electric liquid level sending units are widely used in marine, on-road, off-road, generator set, and industrial applications. The electric liquid level sending unit utilizes reed switch and magnetic field technology.
The standard resolution of KUS level senders are 12-21mm; that means you will get a discrete step reading every 12-21mm. KUS also offers more advanced technology, such as AMR, which allows for a higher resolution of steps, as small as 1mm, for special application needs. here
Liquid Level Sender with American standard output (240 ohms at empty, 33 ohms at full).
For European Standard Output (0 ohms at empty, 180 ohms at full) or other customized outputs range, such as other ohm values or voltage (V) or current (mA), or if you need lengths other than 4″ – 60″, please contact us directly for more information.
The electric liquid level sending units are widely used in marine, on-road, off-road, generator set, and industrial applications. The electric liquid level sending unit utilizes reed switch and magnetic field technology. The advantage of reed switch type level sender over thick-film swing arm type level sender is the reed switch’s durability and reliability. Additionally, in reed switch level senders the float is the only moving part of the sender, thereby minimizing potential mechanical failures. here