Fuel guage and DUMB PO problems.
06-22-2019, 02:06 PM
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Car: 91 camaro rs
Engine: 305 tbi
Transmission: Automatic
Axle/Gears: Posi 3.73
Fuel guage and DUMB PO problems.
I have a 1991 rs with a 305 tbi. And my gas guage would always show a quarter tank and every once in a while it would show 3 quarters full. Now i finally got to tackling this problem and found "more" stupid things the PO had done. I unplugged the connector and the gas guage went to full which i thought was normal but ive seen youtube videos saying that when its unplugged it needs to show empty. I cant seem to find any wiring diagrams but i have found that the puple wire runs to the guage and the grey is the pump. And thats about it. I have a strong feeling it's a float problem. But i haven't taken the whole sending unit out yet. Also there is a strange yellow wire that the PO wired to the float resistor and thats another thing that could be problematic. All ive dobe was pulled the sending unit out a little then shined a light in to see whats going on in it. But before i pull the whole sending unit out i would like to have the correct wiring diagram. If anyone could help it would be most appreciated. Also its my daily driver for at least the next month or 2 so i dont really have much time to any major things like taking the whole sending unit out. So when i do u want to be sure i have the correct info. Anyobe who can get me a wiring diagram. I woukd be so thankful
06-24-2019, 03:52 PM
#2
Re: Fuel guage and DUMB PO problems.
I have a 1991 rs with a 305 tbi. And my gas gauge would always show a quarter tank and every once in a while it would show 3 quarters full. Now i finally got to tackling this problem and found "more" stupid things the PO had done. I unplugged the connector and the gas gauge went to full which i thought was normal but I've seen Youtube videos saying that when its unplugged it needs to show empty. I cant seem to find any wiring diagrams but i have found that the purple wire runs to the gauge and the grey is the pump. And that's about it. I have a strong feeling it's a float problem. But i haven't taken the whole sending unit out yet. Also there is a strange yellow wire that the PO wired to the float resistor and that's another thing that could be problematic. All I've done was pulled the sending unit out a little then shined a light in to see whats going on in it. But before i pull the whole sending unit out i would like to have the correct wiring diagram. If anyone could help it would be most appreciated. Also its my daily driver for at least the next month or 2 so i don't really have much time to any major things like taking the whole sending unit out. So when i do u want to be sure i have the correct info. Anyone who can get me a wiring diagram. I would be so thankful
Hi Michael , I will post two wiring diagrams , one for your engine/ECM including your fuel pump , and one for your fuel gauge . To answer your question , with the sending unplugged (open circuit) the fuel gauge is indeed supposed to read past full . Conversely , with the sending unit wire grounded the gauge should read empty .
The confusion about the gauge functionality comes because the coolant temperature gauge works opposite of the fuel gauge , temperature gauge sender unplugged (open circuit) = Cold reading (bottom of the scale) , temperature gauge sender wire grounded = hot reading (top of scale) .
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