fuel gauge/ speedo
05-29-2013, 10:35 PM
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fuel gauge/ speedo
hey fellas i got an 89 f150 and here is the deal only the rear tank works and the gas gauge has always been way off. anyways i put in new hp fuel pump and new rear pump and sending unit about 6 months ago. gas gauge worked better when it said empty i had really little under half tank. i started dorking around with that thing thinking it was a bad ground and now it is pegged past full all the time. i never really cared because i just went by mileage well now my speedo crapped out. i put new speed sensor in the t case and no dice. it will only work when you hit around 2000 rpms and when you let off gas speedometer falls to zero. so my question is one or the other i dont care i got to have one going i cant ride around with a gas jug in my truck all the time. any suggestions before i put in a new speedo cable. and i forgot to mention i snagged instrument cluster from junk yard and nothing changed so i am gonna rule that out. and one last bit i can ohm out the yellow and blue wire from sending unit has around 71 ohms with truck off turn key to run and it is open. this is probably something simple but somebody please pass some wisdom before i knock the dust off of my remington 870 express and get even with this thing
05-29-2013, 11:02 PM
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the teeth looked little thin on the driven gear on the t case side i might try to look around for one but will prolly have to order that as old as it is that is really all i was thinking could be wrong with speedo and that is more than likely the route i will go. unless some one knows any thing with that gas gauge if it involves dropping that rear tank again i will have to pass on it lol
05-29-2013, 11:08 PM
#4
To test the gauge ground the signal wire. Grounded the needle will go all the way one direction, I don't remember which direction. Ungrounded it will go the other direction. Key on. On 4x4s the speedo drive gear sometimes comes loose off the tailshaft and won't spin the driven gear.
05-30-2013, 03:30 PM
#5
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The driven year and the drive gear are both available new, and inexpensive. Just google it, there several online retail sellers. Get another person and spin the cable at the t case a little bit, the speedo should move, if not, you have a cable/speedo indicator problem. If it moves, there is a problem with the drive gear in the tailshaft housing or the driven gear on the cable.