A better fuel sender??

[imq707s]

Does anyone know of a fuel sender that doesn't bounce all over the place when I'm running? The sender I've got in my Vegas will bounce from 1/4 tank to full the entire time I'm out cruising around. When it stops bouncing, I know it's time for some gas :D

Are there better senders out there that don't bounce up and down as bad?

Thanks:confused:

[mendo]

Conventional float-arm style fuel tank senders consist of a small wiper arm that moves up and down with changing fuel levels and a processor that sends electronic impulses to the gauge for analog or digital output. The arm rides on a rheostat. Older units have a wire-wound rheostat. Vibration and shock eventually erodes and breaks the wire, creating incorrect readings on the gauge. Corrosion of the unit also contributes to erratic readings. Another type of sender has a ceramic rheostat screened with conductive ink. While it doesn’t have wires to break, the wiper gradually wears where it crosses the rheostat from debris contained in the fuel. This occurs with a wire-wound unit as well.

Continuity Check
Disconnect the DC power supply first. Before removing the sender, check all wires and connections at the tank and gauge. Corroded or loose terminals, or a poor ground, may be at fault. If not properly grounded, the gauge pegs out at full and stays there. If the system proves fault-free, your next step is to check the continuity of the sender with a multimeter (VOM).

Disconnect the sender from the gauge. Attach a VOM, the positive (red) lead to the sender’s output post and the ground (black) lead to the sender’s flange on the tank. Most marine fuel senders have a resistance of 33ohms to 240ohms. Using the gauge as your guide, the VOM reading on the resistance scale should indicate 33ohms with a full tank, 240ohms at empty and somewhere between 80ohms to 120ohms when half full. A more accurate test is to unscrew the sender from the tank, attach it to a VOM (as above), and manipulate the float arm, moving it to the full (up) and empty (down) position while noting the resistance on the VOM. If the sender checks out, the gauge may be at fault. But before removing, obtain another sender that you know works and connect it to the gauge. Troubleshooting fuel gauges normally requires a decade box and the services of a marine electronics’ specialist

Match Don’t Mix
Before purchasing a replacement, you’ll need to measure the fuel tank depth. Senders are available for varying tank depths. Manufacturers don’t recommend mixing the resistance of a gauge and sender. For best performance, a 240ohm gauge, for example, must be matched with a 240ohm sender. Your dealer can help determine the correct sender if you know the brand and model number.

Conventional float-arm style fuel senders are less reliable, especially on large horizontal tanks, than more expensive probe-type units with no moving parts. A tank with a depth of 41cm (16"), for example, has a 23cm (9") bracket and 30cm (12") float arm. Vibration and signal amplification from float arms longer than 51cm (20"), the recommended maximum, can break or cause erratic readings. For powerboat use, select a sender with a heavy metal bracket to absorb some of the shock from pounding.

New senders install in the same standard SAE five-hole flange opening making the installation easy. Use the same wires to connect the sensor to the fuel gauge, provided they are in good shape and are marine grade (many older boats have automotive-style wiring.) Float-arm style fuel senders are more difficult to install due to accessibility. Be sure to mount the float arm correctly so it doesn’t touch the tank sides and it swings in the right direction. Fuel sender kits are available and help to eliminate some of the guesswork.

[pyro]

There's nothing wrong with your sender. Mine does the same thing. The long, narrow fuel tanks in our boats tend to slosh the gas around quite a bit when we're running, so the sender "float" in the tank is constantly going up and down. As long as you see the needle rising plenty above zero as it bounces, you'll know there's still enough fuel in the tank. It will read correctly when you're running in a straight line for a while, or idling slow. What's wrong with idling for a minute or two anyway?

If the needle makes instantaneous jittering jumps on the dial when you're slowly rocking in waves, that may indicate a bad sender.

I don't think your system has any kind of processor. I'm pretty sure it's simply voltage dependent. The rheostat in the tank changes the voltage that is sent to the gauge, kind of like a trim gauge and sender.

[MarkHP]

welcome to the club ....... The only way to get a steady reading is to either have a heavily dampened gauge or have a baffled tank. Cars used to use a 'hot-wire' type gauge that would take several seconds to reach a reading when turned on, this would 'average out' the signal as gas sloshed around in the tank. Nowdays I thing the gas gauge in autos are controled by the CPU (what isn't) so the old type 'hot-wire' gauge isn't used anymore. Without adding some electronics to your gauge there is not much you can do. As Pyro says just idle and check it then. In fact you could also make a simple 'dip-stick' and then you would be sure.

[SKATER241]

TRY MIKE AT LIVORSI MARINE.HE MAKES A MECHANICAL SENDER THAT WONT BOUNCE.YOU WILL NEED TO KNOW THE DEPTH OF YOUR TANK.COST IS AROUND SIXTY BUCKS.

[pyro]

I'm pretty sure you can slow down the needle's bouncing by connecting a capacitor with the sender. I'll have to investigate when I get back on the water. Maybe two caps' , one from sender to +12 and another from sender to ground. The value of the cap(s) would determine the damping effect. Improper guesswork here could burn up the gauge...

Techno? you're an electronic geek, right? Are you reading this?

[CRMERC]

I have used the livorsi unit that has no moving parts with some success. It has adjustments for full and empty readings plus it seems to be slow to react which means less gauge wiggle.

[MarkHP]

I tried the capacitor route. With a resistance of 30 Ohm you need a BIG capacitor. Even then it did not make much difference, just pegged the meter when powering up and then was marginaly better. I think if you were to go to the trouble you could do something with a heaverly dampt active circuit, but i guess I am too lazy and just use the dip stick :D

[Techno]

I'm only a gee. Only half an electronics geek. It sounds right though. I think the cap would go parrallal with the resistor though. This forms an RC circuit which is a timer in affect.
Senders ground to signal post.
Pretty sure the no bounce electronic gauges are using stepper motors. Something I was thinking about. Signal drives a motor to place the needle rather than a magnet thing.
Although ugly the CruzPro fuel gauge is digital and has a brain in it. You calibrate it to your tank and then get too much info. % full or empty, gallons in or out that kind of thing. Fuel slosh doesn't affect it.
I think the probe sender kind use air pressure or something like that and usually are damped. Everyone says they work better anyway.

[pyro]

MarkHP, the gauge pegging problem was why I was suggesting one cap to ground and another to +12v. One would need to be bigger than the other, I believe, to bias the load of the sender and gauge...

[MarkHP]

I had a 20, 000 uf across across the sender input and ground, which sholud have given about a 5 sec time delay. Power up and it peged that gauge then slowly came down (5 sec), but not much damping when running so I pulled it out. Don't know what resistance the gauge is but if its low then that would account for it not working much.

[JR IN JAX]

The best thing I have found for fuel quanity used /remaining is my Floscan meter. It tells me what my fuel burn rate is and the "totalizer" gives me a resetable LCD readout of how many gallons [in tenths] I have burned. I think they are less than $400.00 at Boatfix.com. They are much less expensive that running lean [out of fuel].
JR