Fuel Gauge
Thread Starter
|
Mountain Pass
Joined: Aug 2012
Posts: 100
Likes: 4
From: Wisconsin
Fuel Gauge
Good Morning, I'm having a little trouble with my fuel gauge. When the tank is full, the gauge reads 3/4. Is it the gauge or a sensor in the tank?
Also, if anyone can direct me to a good place to buy parts for my 79 F-250, it would also be much appreciated.
Thanks in advance for any help.
Also, if anyone can direct me to a good place to buy parts for my 79 F-250, it would also be much appreciated.
Thanks in advance for any help.
More Turbo
Joined: Mar 2022
Posts: 692
Likes: 211
honestly, it could be either. There is float in the tank (sender) that will have changing resistance depending on it's height (level of fluid). It might be stuck, or the gauge itself could be bad. I would say the sender would be an easier project to tackle than getting the gauge cluster removed, but will likely involve dropping the fuel tank.
Look into LMC truck, Bronco graveyard, and rock auto for parts depending on what you need. I found that LMC has some good exploded diagrams that show you all the parts for each system you're looking to replace/upgrade. They also have a downloadable catalogue for your year/make/model truck with all the different parts numbers. I found this to be extremely helpful.
Look into LMC truck, Bronco graveyard, and rock auto for parts depending on what you need. I found that LMC has some good exploded diagrams that show you all the parts for each system you're looking to replace/upgrade. They also have a downloadable catalogue for your year/make/model truck with all the different parts numbers. I found this to be extremely helpful.
Moderator & parts slinger
Joined: Feb 2007
Posts: 50,150
Likes: 5,783
From: S/W Missouri, Polk county
At least it is still indicating something, so safe to say YES it is the sending unit going bad or the float has a pin hole and getting fuel in it.
I just got this for my truck from Bronco Graveyard. And they are 3/8 pickup tube diameter.
https://shop.broncograveyard.com/197...uctinfo/20331/Disconnect the wire that goes to the fuel sending unit at the tank. Ground that wire to the frame, making sure the frame is clean. Turn the ignition to the "run" position and watch the fuel gauge. If the gauge swings all the way to full, either the sending unit itself is bad or it has a bad ground. If the gauge stays on empty then either the gauge is bad or there is a wiring problem.
To pop the plug off for the test, you can barely get up in there with your head and see the plug. While looking at it, VERY CAREFULLY use a screwdriver to pry it off. AND I MEAN VERY CAREFULLY. It is only pushed on like a 1/8". This is only if you can’t get it with your hands.
Once you have done the test (above) and decide it’s the sending unit. And you have cleaned the ground and that did not work. Then disconnect the ground again and fuel line and read on….
If you can't get either one disconnected, no worries you will have a little more room once the tank is dropped down a little. But make sure you have some wire slack in the plug connector.
Run the tank dry or almost or siphon it empty, I would not do it with ½ a tank of fuel, but if you just have to, just use a big floor jack and a piece of 2x2 plywood. It’s not heavy at all, unless you have it full or 1/2 full of gas. I'd just DRAIN THE TANK!
Loosen the filler and vent hose clamps at the tank end and maybe you can pop the lines off? But most of the time you have to just loosen the clamps and wait till the tank is about out.
With the jack in place, or not, just loosen the hdwr (2 bolts) on the front straps, and remove the tank straps aft hdwr all together, then swing the straps out of your way.
Slide the tank to the dvrs side about 1/2" and then pull out or let the passenger side come out of the frame. Then disconnect the elec connector and eng feed fuel line if you could not get to them earlier. And the EEC small vent line on the top center of the tank, if you have that kind of tank.
Then slide it as far as you can to the right and pop off the filler/vent lines. Sometime you need to carefully put a flat tip screwdriver in between the rubber hose and the tank to break it loose. The filler neck and vent lines get stuck to the metal pretty good sometimes.
Once the tank is removed there is a lock ring that comes off with a screwdriver or punch, look for a small tab that has been bent over to lock it. Un-bend it, tap off the lock ring, remove the sending unit.
Insp the underside of the tank where the support straps rest, lots of dirt and moisture build up there, and that causes the bottom side corners to rust out. You can also come reinstall time replace the anti-chaff material. Old 2" ratchet strap work great, glued to the support straps.
Insp the inside of the tank, might be a great time to replace it all together? Before you reinstall anything connect the electric connection and ground to the sending unit. Wire it up under the truck so it is not hanging by the connection. And with the key in the 1st (on position) you should be able to move the float arm and see a difference in your gauge?? It is always easier to do this with a helper.....
Replacement tank come coated with a primer now days.
I just got this for my truck from Bronco Graveyard. And they are 3/8 pickup tube diameter.
https://shop.broncograveyard.com/197...uctinfo/20331/Disconnect the wire that goes to the fuel sending unit at the tank. Ground that wire to the frame, making sure the frame is clean. Turn the ignition to the "run" position and watch the fuel gauge. If the gauge swings all the way to full, either the sending unit itself is bad or it has a bad ground. If the gauge stays on empty then either the gauge is bad or there is a wiring problem.
To pop the plug off for the test, you can barely get up in there with your head and see the plug. While looking at it, VERY CAREFULLY use a screwdriver to pry it off. AND I MEAN VERY CAREFULLY. It is only pushed on like a 1/8". This is only if you can’t get it with your hands.
Once you have done the test (above) and decide it’s the sending unit. And you have cleaned the ground and that did not work. Then disconnect the ground again and fuel line and read on….
If you can't get either one disconnected, no worries you will have a little more room once the tank is dropped down a little. But make sure you have some wire slack in the plug connector.
Run the tank dry or almost or siphon it empty, I would not do it with ½ a tank of fuel, but if you just have to, just use a big floor jack and a piece of 2x2 plywood. It’s not heavy at all, unless you have it full or 1/2 full of gas. I'd just DRAIN THE TANK!
Loosen the filler and vent hose clamps at the tank end and maybe you can pop the lines off? But most of the time you have to just loosen the clamps and wait till the tank is about out.
With the jack in place, or not, just loosen the hdwr (2 bolts) on the front straps, and remove the tank straps aft hdwr all together, then swing the straps out of your way.
Slide the tank to the dvrs side about 1/2" and then pull out or let the passenger side come out of the frame. Then disconnect the elec connector and eng feed fuel line if you could not get to them earlier. And the EEC small vent line on the top center of the tank, if you have that kind of tank.
Then slide it as far as you can to the right and pop off the filler/vent lines. Sometime you need to carefully put a flat tip screwdriver in between the rubber hose and the tank to break it loose. The filler neck and vent lines get stuck to the metal pretty good sometimes.
Once the tank is removed there is a lock ring that comes off with a screwdriver or punch, look for a small tab that has been bent over to lock it. Un-bend it, tap off the lock ring, remove the sending unit.
Insp the underside of the tank where the support straps rest, lots of dirt and moisture build up there, and that causes the bottom side corners to rust out. You can also come reinstall time replace the anti-chaff material. Old 2" ratchet strap work great, glued to the support straps.
Insp the inside of the tank, might be a great time to replace it all together? Before you reinstall anything connect the electric connection and ground to the sending unit. Wire it up under the truck so it is not hanging by the connection. And with the key in the 1st (on position) you should be able to move the float arm and see a difference in your gauge?? It is always easier to do this with a helper.....
Replacement tank come coated with a primer now days.
Moderator & parts slinger
Joined: Feb 2007
Posts: 50,150
Likes: 5,783
From: S/W Missouri, Polk county
Parts Vendors & Resources
Dennis Carpenter Ford Restoration Parts
National Parts Depot:Ford Truck Parts & Accessories | 1948-1979
MAC's Antique Auto Parts
Blue Oval Truck Parts
Jeff's Bronco Graveyard
LMC Truck - Ford Truck Parts and Truck Accessories
The Early Ford Store-San Dimas,CA
Truck & Car Shop (Orange, CA): 48-86 Ford Trucks, 66-86 Ford Bronco
C&G Early Ford Parts: 32-79 Ford Trucks (Escondido,CA)
Sacramento Vintage Ford
Flashback F-100s: 48-2008 Ford Truck Parts
Vintage Pickup Truck Parts & Restoration Resources Directory
Green Sales Company - Vintage NOS & OEM Parts
TABCO Inc.- US Made!Replacement Sheetmetal & Parts
Dennis Carpenter Ford Restoration Parts
National Parts Depot:Ford Truck Parts & Accessories | 1948-1979
MAC's Antique Auto Parts
Blue Oval Truck Parts
Jeff's Bronco Graveyard
LMC Truck - Ford Truck Parts and Truck Accessories
The Early Ford Store-San Dimas,CA
Truck & Car Shop (Orange, CA): 48-86 Ford Trucks, 66-86 Ford Bronco
C&G Early Ford Parts: 32-79 Ford Trucks (Escondido,CA)
Sacramento Vintage Ford
Flashback F-100s: 48-2008 Ford Truck Parts
Vintage Pickup Truck Parts & Restoration Resources Directory
Green Sales Company - Vintage NOS & OEM Parts
TABCO Inc.- US Made!Replacement Sheetmetal & Parts
Moderator & parts slinger
Joined: Feb 2007
Posts: 50,150
Likes: 5,783
From: S/W Missouri, Polk county
Some of it is from fellow FTE members and the bottom part is a walk thru I wrote up on gas tank dropping 101.
What works for me, might not work for everyone else. Report back your outcome.
What works for me, might not work for everyone else. Report back your outcome.
Thread
Thread Starter
Forum
Replies
Last Post
Idlewild24
1973 - 1979 F-100 & Larger F-Series Trucks
1
Jun 3, 2014 11:55 PM
carter442
Pre-Power Stroke Diesel (7.3L IDI & 6.9L)
3
Dec 24, 2008 10:26 PM
