Fuel gauge

[superdave1984]

So when I bought this monster 97 XJ (350/700R4 combo with a carb) I am driving, I knew the fuel gauge was not working. No biggie. So I get an Intellitronix digital gauge and a universal sender and install them. Works great. Except.....the gauge is all over the place because of the fuel sloshing around in the tank. How do I make it stop doing that? A resistor inline on the wire from the sender? If so, what kind?

I also have an Equus fuel gauge that I found in the glove box while running power to the one I just bought. I'm gonna see how much bounce it has too. I really want to use the digi one because it's not nearly as deep as the Equus (meaning an easier install/mod to the factory cluster), plus it just looks cool. Can't use the factory Jeep sender as I trashed it because I didn't need the electric pump anymore and it's all one unit. Plus all electrical stuff ran through the computer, which is also gone.

Any thoughts?

 

[adsm08]

Factory would have had an anti-slosh unit to keep that from happening. I'm kinda surprised that your digital setup doesn't have one.

 

[adsm08]

Called their tech support line and asked the guy about this. He said to check all your wiring connections and make sure the sender is grounded properly. If the sender is mounted near the center line of the tank it shouldn't have a lot of slosh issues.

 

[superdave1984]

It wasn't feasible to put the sender in the center, but it's about 1/3 of the way from center to one side if that makes sense. Sender and gauge are both grounded to the body. XJ's have no frame. Gonna run a ground strap from the battery to the body and if that doesn't help I'll run a ground directly from the battery to both.

 

[Psychopete]

I think you're going to need a different tank with provisions to prevent sloshing, find a factory module that operates similarly in spec, or build an anti-slosh module. Edit: Or use the original sender and wire up the factory anti-slosh module and save your new stuff for another project down the road.

 

[superdave1984]

The factory sender isn't inside a baffle either, but it didn't fluctuate because the signal went through the Jeep's computer. It's the factory gas tank and it's plastic and I don't have a clue how I would construct a baffled area inside there.

 

[Psychopete]

If you know C, you could build a module using one of these probably:

http://www.pjrc.com/store/teensy_pins.html

Or an Arduino board, similar microprocessor. The language is strait forward, it's getting creative with the solution for something that works. I built an electronic drum set with piezo pickups from the ground up and my dad never thought that I would be able to deal with that sort of signal, but dealing with shitty data is what I do for a living..

Probably can use a voltage regulator from a RBV dash to get it down to 5 volts, or a car charger that has a USB end.

My thoughts would be to set a base line when the ignition is turned on, and keep a running average of signal. If it's a digital signal, it's going to get tricky. But you'd want to throw away any spikes in the signal that are out of a tolerance (the tolerance you'd want to mess with trial/error, 10% of the average may be a good start, but I could see this going exponential). Keep track of what you're throwing away to determine if something drastic happened with the signal, and start over with a new average for correcting itself. When a signal is thrown away, return the average that you're keeping to prevent it from spiking on the gauge.

 

[martin]

A small electrolytic capacitor across the gauge might calm it down. Just guessing on size but 5 micro farad rated for at least twenty volts.

 

[Psychopete]

That would help on an analog signal for sure, but caps can have some undesirable effects. If it's truely a digital signal, running a cap is really going to hose the signal. But it probably is analog.