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SuperRob
New Member
- Joined
- Aug 7, 2007
- Messages
- 135
- Reaction score
- 1
- Points
- 0
- Location
- Victoria BC
- Vehicle Year
- 1989
- Make / Model
- Ford
- Engine Size
- 2.9
- Transmission
- Manual
So my fuel gauge doesnt work.
I got another sending unit from another truck (a few years older) with the plug.
My original plug was in bad shape, so I spliced this one in. The only difference in the plug was that the main power and ground wires were opposite, so I changed that when I respliced it in. Its wired the same as it originally was.
I was hoping that that would fix my problem, but it hasnt.
The pump works fine.
I also tested the rheostat between the signal wire terminal and the ground terminal to make sure that it was functioning correctly, and it appears to be. With the float at empty, it reads roughly 25 or so ohms and when the float is at the top it reads something like 250 ohms or something...
When I have the float at the bottom and turn the key on, it reads empty.
When I have the float at the top and turn the key on it reads full.
When I have the float about 1/3 of the way from empty and turn the key on it reads correctly.
If I have the float at the top, turn the key on, and then move the float to the empty position, the gauge doesnt move at all. Even after about 2 minutes.
If I have the float anywhere above the 1/3 tank level it reads full.
Basically, Full work, empty works, anything in the middle doesnt work. IT also doesnt move as the float moves. I understand that there may be a delay to compensate for shifting fuel load, but 2 minutes should be long enough for it to start moving the gauge.
Whats goin on?
I also checked the rheostat on the 'new' (but old as dirt) sending unit, and it doesnt work at all so I'm not putting it in. It appears that the original sending unit should be fine but I'm unable to figure this out on my own.
Pointers?
Maybe a little NASA experience?
Help?
Thanks!
Heres the situation.
I got another sending unit from another truck (a few years older) with the plug.
My original plug was in bad shape, so I spliced this one in. The only difference in the plug was that the main power and ground wires were opposite, so I changed that when I respliced it in. Its wired the same as it originally was.
I was hoping that that would fix my problem, but it hasnt.
The pump works fine.
I also tested the rheostat between the signal wire terminal and the ground terminal to make sure that it was functioning correctly, and it appears to be. With the float at empty, it reads roughly 25 or so ohms and when the float is at the top it reads something like 250 ohms or something...
When I have the float at the bottom and turn the key on, it reads empty.
When I have the float at the top and turn the key on it reads full.
When I have the float about 1/3 of the way from empty and turn the key on it reads correctly.
If I have the float at the top, turn the key on, and then move the float to the empty position, the gauge doesnt move at all. Even after about 2 minutes.
If I have the float anywhere above the 1/3 tank level it reads full.
Basically, Full work, empty works, anything in the middle doesnt work. IT also doesnt move as the float moves. I understand that there may be a delay to compensate for shifting fuel load, but 2 minutes should be long enough for it to start moving the gauge.
Whats goin on?
I also checked the rheostat on the 'new' (but old as dirt) sending unit, and it doesnt work at all so I'm not putting it in. It appears that the original sending unit should be fine but I'm unable to figure this out on my own.
Pointers?
Maybe a little NASA experience?
Help?
Thanks!
Heres the situation.
