fuel gauge
Thread Starter
|
Junior User
Joined: Jun 2002
Posts: 79
Likes: 0
fuel gauge
on my 72 f100, when the tank is filled. the gauge shows 3/4 full. when filling up when on empty, i can only get 14.50 gallons in the tank. i should be able to put 4 more gallons in the tank. why isn't the gauge showing an accurate reading?
Fleet Mechanic
Joined: Sep 2003
Posts: 1,279
Likes: 0
From: savannah,ga
most likely the float has allowed gas inside and giving a false reading. carry a gallon can of gas when reading E. when it stops then your empty. add the gallon then fill it up to get accurate
tank capacity. if its still 14.5 then the gauge is correct.
if not then you will need to diagnose the gauge circuit.
pull the wire to the float at the tank and ground it to see if the
dash gauge goes to full. if it does then the problem is the float
run until tank is empty and then get it home with one gallon of gas. drop the tank and pull the float unit out to check the float ball
most dealers still stock this part
tank capacity. if its still 14.5 then the gauge is correct.
if not then you will need to diagnose the gauge circuit.
pull the wire to the float at the tank and ground it to see if the
dash gauge goes to full. if it does then the problem is the float
run until tank is empty and then get it home with one gallon of gas. drop the tank and pull the float unit out to check the float ball
most dealers still stock this part
Senior User
Joined: Jun 2003
Posts: 281
Likes: 0
From: Bearspaw (near Calgary)
Like MHG said it's probably the float. My gauge was doing the same thing. I pulled the float and sure enough it had a rusted pinhole leak in it. That allowed the float to fill with gas and not register properly. I just emptied it, sealed it with some seal-all and reinstalled it. Now it works fine.
Moderator
Joined: Dec 2003
Posts: 97,440
Likes: 1,995
From: Saskatoon, Saskatchewan
Originally Posted by rrawlins
Like MHG said it's probably the float. My gauge was doing the same thing. I pulled the float and sure enough it had a rusted pinhole leak in it. That allowed the float to fill with gas and not register properly. I just emptied it, sealed it with some seal-all and reinstalled it. Now it works fine.
Trending Topics
Thread Starter
|
Junior User
Joined: Jun 2002
Posts: 79
Likes: 0
i replaced the sending unit including the float and it didn't make a difference to the guage. what should i do now?
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Ford Super Duty: 5 Things Owners LOVE, 5 Things They LOATHE!
Joe Kucinski
Every 2026 Ford Truck Engine RANKED from WORST to FIRST!
Michael S. Palmer
The Best F-150 Deal of Every Trim Level (XL through Raptor)
Joe Kucinski
Senior User
Joined: Jan 2004
Posts: 211
Likes: 0
From: Spokane, WA
Check the IVR (internal voltage regulator) it's behind the dash gauge panel. Like others have said clean all the connections and check the wiring for grounding/shorting. Also check the gauge itself. I also installed a new sending unit in my 70 F250 and changed out the internal voltage regulator with no noticible difference it still reads 3/4 with a full tank. My next step will be to clean all terminals at the gauge/sender and switch (dual tank setup) Making sure that there is a good ground.
Good luck.
Good luck.
Senior User
Joined: Jul 2003
Posts: 276
Likes: 0
From: Lacey
Can the sending unit be tested with a mutli-meter? If I moved the float up and down could I read the resistance on a multi-meter? I think I have read they are supposed to read from 73 to 12 ohms up to 1989.
