55.2-59 Calibrating the fuel gauge

[BlouDon]

Problem I had was that when the tank was full, the fuel gauge would sit at around 2/3. Measuring the sender when full also produced a reading of around 22Ohm. Applying a 30 Ohm resistor to the wire got the gauge to full, therefore gauge good, sender has an issue.

I removed the sender unit (which looked brand new) and moving the arm to the point where it was reading 22Ohm, it was clear that the arm was physically not moving to the full position. I concluded that the arm was too long so that the float was interfering with the top of the tank.

The arm had two "45º" bends close to the float and I bent these more so they were almost 90º (not quite though). Now the gauge showed full when the tank was full.

Having driven the truck to the point where the gauge now showed empty (needle on the dot near E), I wanted to know how empty the tank really was and siphoned out the remaining fuel. About 10L (2 Gallons) - roughly 30 miles worth - assuming the pickup can access that low.

Now I know the tank is full when it shows full and that I can safely drive it till the needle is on the dot near E and then still have roughly 30 miles in reserve.

[cmayna]

It's always best to make sure your fuel gauge accurately reads when you're at 1/4 tank. It's also much easier to adjust the sending unit's arm when you don't have very much fuel. Thus if you have a 16 gallon tank, put only 4 gallons in and adjust the sending unit's arm until it reads 1/4 tank.

Always make sure the float doesn't leak.

[mr48chev]

I may have to mark this one for future use. I have never had a working gas gauge on my truck since I bought it in 1973. Yes I have walked to a gas station a few times.

I've always filled the tank and have had a pretty good idea of how many mpg I get and could usually guess within a gallon of what it would take on road trips. Putting in a few bucks worth while running around locally was what messed me up. That might be a good game to play with yourself though. keep track of the miles between fill ups and estimate how many gallons it will take to fill it up at gas stops.

[MALIBLOC]

I bought a new sender from Cpp and I still for the life of me can't get it to read full , Im at 4/5 when tank is full and the accurate reading of it at empty is something Im happy with .
I cut the arm , adjusted it , and basically took a break from it , I may try putting a small bend in it, sound like it may work

[BlouDon]

Originally Posted by MALIBLOC

I bought a new sender from Cpp and I still for the life of me can't get it to read full

Can you get a full reading with the sender OUTSIDE the tank?

[MALIBLOC]

yes when the sender is out the truck I can manually get it to full, but when installed it is a hair above 3/4
I tried adjusting a few different times, cut and reinstalled the arm, I may just wait till tank is low again and pull an bend the arm down towards the bottom of tank slightly

[cmayna]

Cutting the length of the lower arm will cause the reading to read lower. You would want to increase the length, if anything. Bending the end of the lower arm downward will cause the reading to be higher.

[jwhotrod]

it really doesn't matter where full is, the important thing is to know where empty is. My car goes empty with 4 gallons in the tank, both as a safety buffer, and to protect the pump in the tank.

[BlouDon]

Originally Posted by MALIBLOC

yes when the sender is out the truck I can manually get it to full, but when installed it is a hair above 3/4

Then I am convinced that your float is interfering with the "ceiling" of the tank.

The objective is to make the arm shorter by bending it so that the float comes closer to the pivot point.

I've made a drawing which I hope will show what I did....

[burnin oil]

Originally Posted by jwhotrod

it really doesn't matter where full is, the important thing is to know where empty is. My car goes empty with 4 gallons in the tank, both as a safety buffer, and to protect the pump in the tank.

Amen. My big dodge runs out of fuel around 1/4 tank. You know to start looking for fuel at 3/8s or 550 miles. Filling a 52 gallon tank with enough diesel to prime the system by gas can just sucks.

[BlouDon]

Originally Posted by BlouDon

the tank is full when it shows full and that I can safely drive it till the needle is on the dot near E

My point is: IT IS POSSIBLE to have the gauge show full when full and empty when empty - as it should. It just requires a bit of perseverance and patience.