Obviously, the fuel in our tanks sloshs around as you drive, and even after you stop for a minute. My question is this; what electrical devise is used, and how is it wired into the circuit that "smoothes" out the signal coming from the fluctuating sending unit? Is is a capacitor or what? The reason why I ask is not third gen exactly, but the tech aspect of is is universal, therefore thrid gen related. I put a new sending unit in my boat. The old one didn't work at all.

The old one was a tube that went to the bottom of the tank. It had a float inside the 1" dia tube. Attached to the float was two magnets. These magnets slide with the float past a 1"x 12"(the depth of the tank) printed circuit board that some how senses the position and generates the proper resistance to send the correct votage back to the gauge. The sloshing is "dampend" by there being only two tiny holes drilled in the otherwise enclosed tube. This allows the float to get an "average" reading since the gas can enter and exit the tube slowly, and is not immediately affected by sloshing fuel.

SOOO. I replaced this total piece of **** with a "normal" Float/arm/reostat(sp?) type sending unit. It works fine, but the gauge jumps around like crazy as the fuel sloshes in the tank.

So that is why I'm wondering what I can use for and electrical "shock absorber". I'm pretty sure the thing to use is a capacitor, but I'm not sure where to wire it, or what size to get. TIA

 

The way alot of factory gas gauges work, is that the sending unit energizes a heating element in the gauge, and the pointer is connected to a bimetal. That averages the level over about a 15 to 30 second period.

To do that with a capacitor, you would need a really enormous value, up in the many thousands (maybe hundreds of thousands) of microfarads. It would work but I don't know how practical it would be.

I wonder if you could just change out the gauge for one that uses the heater/bimetal system?

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"So many Mustangs, so little time..."
ICON Motorsports

 

I love learning new things, and i just learned something new. I thought car gas gauges were basically "volt" meters, like my boat one is. Thanks RB! I'll have to see what I can find for a different type of gauge.

[This message has been edited by Tom 400 CFI (edited July 17, 2001).]

 

Watch out for one thing.... most factory gas gauge sending units are arranged such that they have zero resistance at empty, but alot of aftermarket ones (Stewart-Warner for example) are connected with max resistance at empty. Obviously the SU and the gauge need to work off the same logic.

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"So many Mustangs, so little time..."
ICON Motorsports