New and need help with gauges on 5.0

ineeda5.0

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Jan 7, 2010
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I just bought my 89 5.0 hatchback about 2 months ago.... Since i have bought it i know the speedometer is not giving the accurate speed it is approx. 20mph under the speed I am actually going. I changed the speedocable and that didnt help... Now all of a sudden my gas meter gauge isnt working properly, No matter how much gas I have the needle stays past the FULL mark and does not go down.... Could it be the cluster in itself??
 
are the other gauges working properly? if not i would say the IVR is bad. if it's just the gas gauge... could be the gauge itself or the sending unit.
as for the speedo...sounds like the wrong speedo gear. have the rear end gears been changed? 20 mph is alot to be off. sounds like you're running 33 inch off road tires :rlaugh:
 
are the other gauges working properly? if not i would say the IVR is bad. if it's just the gas gauge... could be the gauge itself or the sending unit.
as for the speedo...sounds like the wrong speedo gear. have the rear end gears been changed? 20 mph is alot to be off. sounds like you're running 33 inch off road tires :rlaugh:


To my knowledge there are no rear gears, I dont care too much about the speedometer as I do knowing how much fuel i have in my tank :nonono:,
The gauge always worked funny, the needle would always stay about an inch above the Full marker for about 15-20 minutes and then it would accuretly depict how much gas I had in my tank.... But recently it just stays at the top of the Full marker an doesnt budge
 
my fuel gauge is broke too, stays a E though, changed sending unit, still broke. anybody know if it has a fuse or relay?


It has a anti-slosh module also known as the internal voltage regulator built in to the back off the cluster, from what people tell me this is usually the problem with my the fuel gauge goes bad... But I have a 89 and the only voltage regulators i find are for 90-93 foxbodys, I dont know if the 89's dont have any voltage regultators orr if they do or if im just better replacingthe whole cluster, any advice would be greatly appreciated
 
i'll put $20 down its your fuel level sending unit. had it fail in 2 of my 3 foxes.

it will usually drop clear down to nearly empty usually when you get extremely low on gas/out of gas. not a good way to test it, but its always worked for me.
 
i'll put $20 down its your fuel level sending unit. had it fail in 2 of my 3 foxes.

it will usually drop clear down to nearly empty usually when you get extremely low on gas/out of gas. not a good way to test it, but its always worked for me.


Considering im pretty limited to tools and am not to mechnically inclined as this is my first mustang, how hard are the sending units to change if i did it myself?? What tools would i need and also why dont you think it could be the voltage regulator in the cluster
 
Considering im pretty limited to tools and am not to mechnically inclined as this is my first mustang, how hard are the sending units to change if i did it myself?? What tools would i need and also why dont you think it could be the voltage regulator in the cluster

i've had the same exact symptoms in two cars, both times it was the sending unit. it's pretty common.

they are not hard to swap. there is 3 bolts inside your gas door lid. you remove those 3 bolts (i think its 3, might be 2?) and that will allow you to wiggle the filler neck out later.

there is one retaining bolt that holds the filler tube in place. this bolt is near the end of the tube where it enters the tank. once that is out, theres a metal bracket that slides free. then there is just 2 straps that hold the tank up. you remove those bolts, and i lay under the gas tank. the LESS fuel you have, the better here.

i let it down onto my chest, and manuver it off me while sliding out from under it. from the rear of the car, there are 2 lock rings on the top of the tank. you just need a flathead screwdriver and a mallet. tap the retaining ring free, lift out the sender, drop in the new one and replace with new retaining ring. the senders always come with a new one.

the right side (from back of car) is the fuel pump assembly, the left side is the sending unit. so in total, you need up to these tools;

jack/jackstands, 3/8" ratchet/sockets, flathead screw driver, mallet.

the last time i did mine, it took me 20-30 minutes. it get's painful if you have alot of gas in the tank though.
 
As for the speedo cable, i'd pull the cable out of the trans and inspect the speedo gear. What color is it? How many teeth on the gear ont he cable.

Then take a flashlight and look inside the hole and see what color the driven gear is.


I bet the gears or something has changed and you'll need to swap the speedo gear to recal the speedometer.