Fuel Gauge Prob and Speedometer

[mburgert]

All righty my fuel gauge after fueling up completely full reads way past full (3 O'Clock) for about 50 miles. Then it starts working like it shoud and sits on full for another 50ish milels like all GM's do then it starts its decline and it works correcly the rest of the way. Whats the deal. And on the speedometer it reads about 7 miles an hour slow when going 60 which obviosly in turn makes the odometer read wrong too. Back tires are 235 75R15 and front are 275 60R15 (i know sized can make a difference on how it reads). Thanks alot guys/gals

[mburgert]

Help please!!!!

[pjmoreland]

I'm pretty sure there's a resistor on the back of the fuel gauge that you might need to replace. Try this place:

http://www.fix-a-gauge.com/

Sounds like you need to swap out the speedometer gears in the tail of your transmission. A good place to start would be to pull the driven gear out of the side of your transmission and see what color the gears are. The colors indicates the number of teeth on the gears. What kind of transmission do you have? Do you know the gear ratio of your rear differential?

Here's a link that might help you.

http://www.tciauto.com/tech_info/speedo_gears.htm

[mburgert]

The fix a gauge site says their kit will work if the gauge says 1/4 tank when full, mine doesnt do that it goes way past full when full (3 oclock) then works fine after about 50 miles. That site also doesnt say whats in the package for 7.95, (a resister?). I know its cheap but will it work. On the speedometer does it matter if my front and back tires are diffent sizes, that site with the revolutions per mile on accounts for 1 tire size. Tranny is TH350. Rear end i dont know but someone can maybe make a good guess as its a 350/350 12 bolt cover 1/2 ton cheyenne. Thanks

[pjmoreland]

The size of your front tires will have absolutely no effect on your speedometer reading. Use your rear tire size for the speedometer gear calculation. Your rear end ratio might be listed on your glovebox door option sticker.