Fuel gauge problem?
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Joined: Jan 2006
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From: Waterloo IL
I had this problem on my highboy. Its really easy to change when the fuel tank is behind the seat!
Moderator
Joined: Jan 2006
Posts: 1,779
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From: Waterloo IL
351m/400? Passenger side, somewhat high up on the front of the block.
Hotshot
Joined: Apr 2009
Posts: 14,333
Likes: 247
From: Stanley, VA
Okay, everything from the gauge to the point you grounded is okay. The problem is after that point.
Before you hook the wiring back up look at the gauge, turn the key to on. Does it move any at all? If not, hook the wiring back up and do it again. Watch the needle and see if it moves at all. If it moves a small amount you may have a sunken float. These can be replaced separate from the sending unit.
If it doesn't appear to move the next step is to check the ground connection from the sending unit. On the sending unit you'll see one short black wire that is attached to the crossmember in front of the sending unit by a screw. Take this screw out and clean both the terminal and the attaching point on the crossmember. Now would be a good time to make sure the terminals and connectors at the sending unit are clean too. Reattach the ground wire and make sure to plug the sending unit back in. Turn the key on and watch the gauge. If it still reads empty the sending unit is more than likely the culprit.
Before you hook the wiring back up look at the gauge, turn the key to on. Does it move any at all? If not, hook the wiring back up and do it again. Watch the needle and see if it moves at all. If it moves a small amount you may have a sunken float. These can be replaced separate from the sending unit.
If it doesn't appear to move the next step is to check the ground connection from the sending unit. On the sending unit you'll see one short black wire that is attached to the crossmember in front of the sending unit by a screw. Take this screw out and clean both the terminal and the attaching point on the crossmember. Now would be a good time to make sure the terminals and connectors at the sending unit are clean too. Reattach the ground wire and make sure to plug the sending unit back in. Turn the key on and watch the gauge. If it still reads empty the sending unit is more than likely the culprit.
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Senior User
Joined: Jul 2011
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Okay, everything from the gauge to the point you grounded is okay. The problem is after that point.
Before you hook the wiring back up look at the gauge, turn the key to on. Does it move any at all? If not, hook the wiring back up and do it again. Watch the needle and see if it moves at all. If it moves a small amount you may have a sunken float. These can be replaced separate from the sending unit.
If it doesn't appear to move the next step is to check the ground connection from the sending unit. On the sending unit you'll see one short black wire that is attached to the crossmember in front of the sending unit by a screw. Take this screw out and clean both the terminal and the attaching point on the crossmember. Now would be a good time to make sure the terminals and connectors at the sending unit are clean too. Reattach the ground wire and make sure to plug the sending unit back in. Turn the key on and watch the gauge. If it still reads empty the sending unit is more than likely the culprit.
Before you hook the wiring back up look at the gauge, turn the key to on. Does it move any at all? If not, hook the wiring back up and do it again. Watch the needle and see if it moves at all. If it moves a small amount you may have a sunken float. These can be replaced separate from the sending unit.
If it doesn't appear to move the next step is to check the ground connection from the sending unit. On the sending unit you'll see one short black wire that is attached to the crossmember in front of the sending unit by a screw. Take this screw out and clean both the terminal and the attaching point on the crossmember. Now would be a good time to make sure the terminals and connectors at the sending unit are clean too. Reattach the ground wire and make sure to plug the sending unit back in. Turn the key on and watch the gauge. If it still reads empty the sending unit is more than likely the culprit.
so i guess my float is sunken..
its funny though b/c after i tested the ground on the wiring harness, i quickly connected it back to the tank and i watched the needle go down and stop at about a quarter of tank(thats how much i have in the tank right now)
anyways, do i have to drop the tank to replace the float?
Hotshot
Joined: Apr 2009
Posts: 14,333
Likes: 247
From: Stanley, VA
Here is a picture of the sending unit. The float is to the left side of the unit. You can see that it just "clips" to the float arm.
I think you can pull the sender out without dropping the tank but not 100% sure. The bed was off mine.
I think you can pull the sender out without dropping the tank but not 100% sure. The bed was off mine.
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so Its that gray thing that's attached to the unit?
Hotshot
Joined: Apr 2009
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From: Stanley, VA
No, the "gray thing" is the rheostat. The float is the round cylindrical object at the left end of the assembly. It has the silver gray "hook" around it.
The other round "thing" with the tube going in the right side of it is the strainer, aka "sock". This is the first fuel filter. It's a coarse nylon mesh that will filter out the big stuff before it gets to the pump.
The other round "thing" with the tube going in the right side of it is the strainer, aka "sock". This is the first fuel filter. It's a coarse nylon mesh that will filter out the big stuff before it gets to the pump.
Hotshot
Joined: Apr 2009
Posts: 14,333
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From: Stanley, VA
I would pull the old one first to see if it is a bad unit and not just a sunk float. If the sender itself is bad I would go with new rather than used.
Hotshot
Joined: Apr 2009
Posts: 14,333
Likes: 247
From: Stanley, VA
One thing you might try. Once the sender is out, plug the harness back in and turn the key on. Hae someone watch the gauge. Move the float arm up and down and see what the gauge does. If it moves, the float is bad if the needle doesn't move, replace the whole sending unit.
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Hey guys, its been a while since i tried, well i havnt really tried droping the tank to fix the problem, anyways
Last week when i got home from school, before i turned my truck, i looked at the gas gauge and noticed it was marking half tank!
The day before that i filled the truck with about 40 bucks(9 gallons) which is very close to a half tank
so i turned off my truck, immediately turned it back on and it was still marking half tank
The next day i turned it on in the morning so i cant let it warm up before school, but once again the needle moved to only right on the E
When i took off, i hoped it would move, but nothing
After school i turned my engine and didnt pay attention to my dash
Half way home i look at the gauge and saw it was reading Half tank
The only thing iv been doing on my truck is using 1st more often
i really dont use it since its the granny gear
Am i not getting enough power to my gauge or something??
or is my truck Mocking me???
Last week when i got home from school, before i turned my truck, i looked at the gas gauge and noticed it was marking half tank!
The day before that i filled the truck with about 40 bucks(9 gallons) which is very close to a half tank
so i turned off my truck, immediately turned it back on and it was still marking half tank
The next day i turned it on in the morning so i cant let it warm up before school, but once again the needle moved to only right on the E
When i took off, i hoped it would move, but nothing
After school i turned my engine and didnt pay attention to my dash
Half way home i look at the gauge and saw it was reading Half tank
The only thing iv been doing on my truck is using 1st more often
i really dont use it since its the granny gear
Am i not getting enough power to my gauge or something??
or is my truck Mocking me???