Fuel sending unit question
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Fleet Mechanic
Joined: Apr 2014
Posts: 1,790
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From: Oakland, AR
Fuel sending unit question
78 F150, 460, C6.
My fuel gauge seems to be stuck right at the full mark and am almost out of fuel in that tank. Can the sending unit be removed without dropping the tank?
Dual tanks with only rear tank installed at this time.
Thanks
Ben
My fuel gauge seems to be stuck right at the full mark and am almost out of fuel in that tank. Can the sending unit be removed without dropping the tank?
Dual tanks with only rear tank installed at this time.
Thanks
Ben
Fleet Mechanic
Joined: Dec 2007
Posts: 1,504
Likes: 339
From: Wildwood Pa
Ben,
Disconnect the wire at the sender, you should be able to do this without dropping the tank. With the wire disconnected, see if the gauge still reads full. If it does, you have a short to ground in the wire that runs from the sender to the gauge.Trace every inch of the wire from front to rear, looking for a spot where the insulation is worn thru & touching metal or another wire. This is just as likely your problem as a bad sender.
Disconnect the wire at the sender, you should be able to do this without dropping the tank. With the wire disconnected, see if the gauge still reads full. If it does, you have a short to ground in the wire that runs from the sender to the gauge.Trace every inch of the wire from front to rear, looking for a spot where the insulation is worn thru & touching metal or another wire. This is just as likely your problem as a bad sender.
Thread Starter
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Fleet Mechanic
Joined: Apr 2014
Posts: 1,790
Likes: 182
From: Oakland, AR
Good thing I haven't installed the midship tank yet. I have a couple three issues going all fuel related. I don't think my sender is bad, just float stuck or out of adjustment.
It also acts like its running out of fuel, yet getting just enough to stay running. The fuel filter at the engine, can't see any fuel in the filter. I have an electric fuel pump on it and I hear it working. So I have a couple more things to check out before I get into the sender. Like make sure something didn't partially plug a line.
Ben
It also acts like its running out of fuel, yet getting just enough to stay running. The fuel filter at the engine, can't see any fuel in the filter. I have an electric fuel pump on it and I hear it working. So I have a couple more things to check out before I get into the sender. Like make sure something didn't partially plug a line.
Ben
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Ford Parts Specialist
Joined: Nov 2006
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From: Simi Valley, CA
Good thing I haven't installed the midship tank yet. I have a couple three issues going all fuel related. I don't think my sender is bad, just float stuck or out of adjustment.
It also acts like its running out of fuel, yet getting just enough to stay running. The fuel filter at the engine, can't see any fuel in the filter. I have an electric fuel pump on it and I hear it working. So I have a couple more things to check out before I get into the sender. Like make sure something didn't partially plug a line.
Ben
It also acts like its running out of fuel, yet getting just enough to stay running. The fuel filter at the engine, can't see any fuel in the filter. I have an electric fuel pump on it and I hear it working. So I have a couple more things to check out before I get into the sender. Like make sure something didn't partially plug a line.
Ben
The float is made of two pieces of brass soldered together. Solder breaks down, gas seeps in, float settles to the bottom of the tank.
I've never seen or heard of a float getting stuck. It attaches to a 'shepherds crook' shaped arm that is part of the sending unit.
Float comes with the sender, but is also available separately. It's the same: 1957/79 FoMoCo Passenger Cars/Trucks, 1961/79 Econoline & 1966/79 Bronco.
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Fleet Mechanic
Joined: Apr 2014
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From: Oakland, AR
That's just it, the gauge does move some. That seems to say something else is going on. I just haven't figured it out yet. And its going to be at least a few days before I get really into it.
Lead Driver
Joined: Jul 2017
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From: San Jose, CA
Well at least being able to pull the connector off as a first test will keep you from having to drop the tank if you find out it's a wiring or gauge thing.
It's way more likely a sender will go bad electrically than the float stick all the way up. Now, out of adjustment, that's a thing for sure! Even brand new ones did not always match perfectly.
Not uncommon on carbureted engines (even with electric fuel pumps) to not see much fuel in the filters. But if there is NONE visible, then that can be a clue.
But how does it run? Does it also act like it's running out of fuel sometimes? Or is it just the filter that you're going by at the moment?
Does the truck sit most of it's life, or is it driven regularly? Fuel pumps fail even from sitting, and frankly these days it seems they fail mostly from sitting.
Good luck.
Paul
It's way more likely a sender will go bad electrically than the float stick all the way up. Now, out of adjustment, that's a thing for sure! Even brand new ones did not always match perfectly.
But how does it run? Does it also act like it's running out of fuel sometimes? Or is it just the filter that you're going by at the moment?
Does the truck sit most of it's life, or is it driven regularly? Fuel pumps fail even from sitting, and frankly these days it seems they fail mostly from sitting.
Good luck.
Paul
Thread Starter
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Fleet Mechanic
Joined: Apr 2014
Posts: 1,790
Likes: 182
From: Oakland, AR
Well at least being able to pull the connector off as a first test will keep you from having to drop the tank if you find out it's a wiring or gauge thing.
It's way more likely a sender will go bad electrically than the float stick all the way up. Now, out of adjustment, that's a thing for sure! Even brand new ones did not always match perfectly.
Not uncommon on carbureted engines (even with electric fuel pumps) to not see much fuel in the filters. But if there is NONE visible, then that can be a clue.
But how does it run? Does it also act like it's running out of fuel sometimes? Or is it just the filter that you're going by at the moment?
Does the truck sit most of it's life, or is it driven regularly? Fuel pumps fail even from sitting, and frankly these days it seems they fail mostly from sitting.
Good luck.
Paul
It's way more likely a sender will go bad electrically than the float stick all the way up. Now, out of adjustment, that's a thing for sure! Even brand new ones did not always match perfectly.
Not uncommon on carbureted engines (even with electric fuel pumps) to not see much fuel in the filters. But if there is NONE visible, then that can be a clue.
But how does it run? Does it also act like it's running out of fuel sometimes? Or is it just the filter that you're going by at the moment?
Does the truck sit most of it's life, or is it driven regularly? Fuel pumps fail even from sitting, and frankly these days it seems they fail mostly from sitting.
Good luck.
Paul
About everything you mentioned its doing. The fuel filter, out of gas, everything.
This week I'm helping my neighbor winterize, so it'll be this weekend or next week before I really get into it.
Ben
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Fleet Mechanic
Joined: Apr 2014
Posts: 1,790
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From: Oakland, AR
update
Finally got some answers on the fuel problem. It appears that the electric fuel pump was the problem. The sending unit works, still didn't get it adjusted enough though. Its reading high.
All the lines are clear, no obstructions. Bypassed the electric pump and the truck is running fine. Even the filter at the engine is filling with fuel.
All the lines are clear, no obstructions. Bypassed the electric pump and the truck is running fine. Even the filter at the engine is filling with fuel.
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