1990 Festiva Fuel Gauge bad Sending Unit

[SLW in Oregon]

Good morning! After 3 years of guessing how much gas I have, I want to fix my non-working fuel gauge. I believe it is a faulty sending unit. When I fill up with gas, the fuel gauge needle goes up to full. It slowly goes down as I use fuel, and then at some point the needle hovers between half to three-quarters full (even though I have only used a few gallons of gas.) And then just after that, the needle drops to empty and stays there until I fill up again.

I have hesitated to tear into it, not wanting to mess with gas and fumes. But now I will, I think! Question, before I start. I believe some units can be repaired. Is there anything on this unit that can be fixed, like a loose solder joint? If not, I found this unit online - does anybody know if it will fit a Festiva like I've read it will? (Sunpro CP7583 Fuel Level Sender)

http://www.amazon.com/gp/product/B00029JXMU/ref=ord_cart_shr?ie=UTF8&m=ATVPDKIKX0DER

Or does somebody have a photo of what the unit should look like? I have a shop manual but the photo is not very clear.

Other than a wrecking yard, do I have any other options?

Thanks much. Shirley in Oregon

[TominMO]

In case you don't know, the fuel level sender in the tank has to be the same range of resistance as the fuel gauge. That Sunpro sender is 33 - 240 ohms. IDK offhand what the stock Festy fuel gauge calls for. Also, it looks like you would have to modify it somehow to make it fit in the Festy tank. Where did you read that it would work BTW?

Edit: you could just buy the aftermarket gauge (shown farther down the page) that is appropriate for that sending unit.

[TominMO]

See post #1 in this thread:
http://www.fordfestiva.com/forums/showthread.php?t=36816&highlight=fuel+ohms

The closest range I could find for a substitute sender is the one for most 1965 - 1997 GM vehicles, which is 0-90 ohms. You would have to modify it to fit and mount in the Festy gas tank. Then you could use the stock Festy fuel gauge, which would be a close enough resistance "fit", at 6-95 ohms.

Or possibly an overseas connection could get the proper part, like someone from the Philippines. Or back to plan A: the junkyard.

Question for Forum members: can the sending unit be tested w/a multimeter for proper resistance along its range? Can it be cleaned up to remove the corrosion that is making it not work right?

[FestYboy]

the sending unit failure is not due to corrosion, but rather the wiper arm rubbing through the resistor coil and breaking the connection. the search is on for the proper wire to rewrap the wiper area and repair the units.

some GM units can be moded to use in a festy, but the polarity MUST be reversed before final install.

[georgeb]

I bought a set of factory alloys off a local man today and he has the complete assembly with sender and pump out of a '91 for $50. He replaced it because his pump was "getting old".

[TominMO]

the sending unit failure is not due to corrosion, but rather the wiper arm rubbing through the resistor coil and breaking the connection. the search is on for the proper wire to rewrap the wiper area and repair the units.

some GM units can be moded to use in a festy, but the polarity MUST be reversed before final install.

What about finding new units from either Mazda or Kia dealerships, with the correct ohm range and maybe even a direct fit? Maybe there are still sending units listed for 323s, older Proteges, etc that will work.

[SLW in Oregon]

Thank you, Tom (in Mo), for your prompt responses and great info. Yes, the range of resistance for the sending unit was vaguely in the back of my mind. Now it's in the front. Thanks. I found the Sunpro a few years ago with searching via 1990 Festiva Fuel Gauge Sender. There was a website, don't remember the name, that had entry fields for Make, Model, and Year, and this is the gauge it came up with. Wanting to be sure, I was reluctant to order it. I don't find the same website, but here it is on a JCWhitney site -

http://www.jcwhitney.com/fuel-gauges/ford-festiva/c27170d618j1s21.jcwx

But, be that as it may, the unit's 33-240 won't work unless I also replace the gauge with the matching one, which I don't want to do if I don't have to.

FestYboy's explanation "the sending unit failure is not due to corrosion, but rather the wiper arm rubbing through the resistor coil and breaking the connection. the search is on for the proper wire to rewrap the wiper area and repair the units" was similar to what a repair garage told me, which is what prompted me to consider tackling it myself, thinking I could simply repair the worn-through area. Rewrapping could be an option, if I, as your FestY suggested, get the proper wire.

Now that I know more about the unit, thanks to all the posts, I am a little braver to dig into it. I will look into the possibility of new units from either Mazda or Kia dealerships, with the correct ohm range, that TomInMo suggested. I'll also check the local wrecking yards. I have also, a couple years ago, spoken with biglay5150, a local fellow forum user that you all probably know. Perhaps he has something.

Thanks for all the input. I will keep checking back for updates, and I'll let you know what I end up doing and if it works!

[91mcnasty]

I'd send you a known good complete unit for 30+ shipping. Problem solved for less than 50 bucks

[BigElCat]

I have this same problem. Yes, the ohm resistance can be read directly with a multi-meter in the ohm setting.

My 2 cents...You guys are correct that the wire windings are what wear through. No the windings can not be replaced. A GM aftermarket sending could be modified to fit, but I haven't tried this yet.

I pulled a unit at the JY and it, too, had the same problem. This sucked because there's a lot of work involved just to pull and test a JY unit.

McNasty's offer is tempting. But any used sender is going to have the wear problem. If we could source a Mazda bolt in 'new' replacement, that would be the best!

[BigElCat]

Here it is, the wear on the sending unit.

There are more windings under the ones that are worn thru. This is how the guage retains partial function. Rewinding it seems out of the question...perhaps there's an old man in Japan that does it for a hobby :p

It's an ambition idea...3,000 wraps in the first layer, constant tension, top over with at least one more layer, and then test it for resistance. You would definitely need a jig to do the wrapping. Do people really do this?

I just made up the 3,000 number...how would you even count them?

Note: This is a carby unit, no fuel pump. I think an EFI unit could be adapted to replace a carby sender. Any pics of an EFI sender?

[BigElCat]

:mumum: Ignore my previous post, except the pics. It is just one layer of windings, I'd guess about 300 of them. I'm on board for the re-wrap.

I haven't found the wire yet...but get this...if I'm not mistaken, any exposed wire wound resistor of the same ohm range and same physical length of the coil would work with modded brackets. This task is not a priority for me. All input is welcome.

[DON SVO]

I'm looking into this as well... I'm replacing my dash cluster with AutoMeter Z series gauges. Because of the dumb backwards Ohm range in the festy, I'm planning to replace my sender with a mustang unit and use the AutoMeter Mustang fuel gauge.

[FestYboy]

^ no need, just have to reverse the polarity at the unit (very easy).

[Bert]

I don't know if anyone alerted you to the fact that there is a gas tank and pump access cover inside the car just behind the rear seat. You do not have to drop the tank to get inside.

[DON SVO]

^ no need, just have to reverse the polarity at the unit (very easy).

Yes, but the Ohm range is not going to be correct for almost any Auto Meter gauge. The sender needs to come out regardless (inop), if this can be done easily then I'm good to go!