Replacing Fuel Sending Unit Float

[chaseincats]

Hi guys,

My gas gauge has never been accurate past the 1/3 emptyish mark.  When the tank has 8 gallons remaining, it will always read as empty (I've tested this by going to the pump the second it reads empty multiple times and I always end up putting in about 8 gallons.

Recently my gauge hasn't been reading full when I top the tank off - it will read maybe around 15 gallons in the tank instead of 18.  I have taken the fuel sending unit out a few times for cleaning and everything inside on the coil/arm (both plug ends too) look great.  I pulled the dash gas gauge and everything in there looks pristine as well.  The real nail in the coffin is when I have the sending unit out and bend the arm up and down to the half and 1/3 mark, it will read that on the gauge so that leads me to believe it's the 40 year old hard-as-a-rock float.

 

TL;DR: My question is, is there a way to replace the float?  A new fuel sending unit from zstore is almost $200 so I'd prefer to steer clear of that if possible.

 

Any ideas?

chase

[David F]

What do you mean "bend the arm" for testing.  Do you mean simply move the arm up and down?  My gauge responds similarly as it reads empty with just less than half tank remaining.  To me, it will be an easy fix by actually bending the float arm down so the gauge thinks there is more fuel in the tank.

[chaseincats]

21 minutes ago, David F said:

What do you mean "bend the arm" for testing.  Do you mean simply move the arm up and down?  My gauge responds similarly as it reads empty with just less than half tank remaining.  To me, it will be an easy fix by actually bending the float arm down so the gauge thinks there is more fuel in the tank.

Sorry, yes I meant moving the arm up and down while watching the fuel gauge.

I'd prefer not to alter anything with the gauge.  Is it really that tough to find something to replace the float with?

 

EDIT: Also, the problem only develops when the tank is less than half full.  Up to that point it is correct I believe.

Edited December 9, 2019 by chaseincats

[AZ-240z]

Why bend the float arm to compensate for inaccurate readings.  If you look 

closely at the float arm pivot point, you will see a small set screw.  This set screw,

when loosened, would allow you to change the sweep of the float arm in relation

to the pickup contacts thus changing the tank fuel level readings.

[chaseincats]

On 12/9/2019 at 2:00 PM, AZ-240z said:

Why bend the float arm to compensate for inaccurate readings.  If you look 

closely at the float arm pivot point, you will see a small set screw.  This set screw,

when loosened, would allow you to change the sweep of the float arm in relation

to the pickup contacts thus changing the tank fuel level readings.

I'd really not like to change any of the calibration.  Are replacement floats (or substitutes) not available?  I was thinking about replacing the float with some Styrofoam but I'm guessing the gas will eat that up, right?

[Patcon]

Styrofoam will last about 10 seconds in gasoline and then you will have a little blob of Napalm...

[chaseincats]

1 minute ago, Patcon said:

Styrofoam will last about 10 seconds in gasoline and then you will have a little blob of Napalm...

Ya exactly haha.  Do they sell the floats anywhere or do you know what they are made of?

[crayZlair]

Try Summit Racing

Gas Tank Sending Unit

[chaseincats]

1 minute ago, crayZlair said:

Try Summit Racing

Gas Tank Sending Unit

Awesome, I'll give this a shot.  Thanks!

[chaseincats]

So as soon as I bought the float (but haven't installed yet), the possible real problem reared its head.  My gas gauge needle now bounces around and sometimes the gauge will just plain die - the needle will fall as fast as if I shut the car off then pop right back up a few seconds later.

I've checked the gauge & fuel sending unit connectors before but don't remember seeing any corrosion at all.  Is the ground for the gauge/sending unit hidden somewhere else in the car or is there something else you guys recommend I check?

 

Here's a brief video of the needle slightly bouncing around: https://www.youtube.com/watch?v=6MJjEKJtesk&feature=youtu.be

 

Any ideas?

-chase

Edited January 5, 2020 by chaseincats

[chaseincats]

Anyone?

Also - on the sender unit, is the wiper arm supposed to contact the the wound wire or just hover above it?

[grannyknot]

6 hours ago, chaseincats said:

Also - on the sender unit, is the wiper arm supposed to contact the the wound wire or just hover above it?

I can't help you with your bouncing needle except to say make sure all electrical connections between the sender and gauge are clean. Also, the wiper arm should touch the wound wire, the wire is one continuous strand from end to end so as the wiper moves up and down so does the resistance and that is what move the needle.

Hmmmm, check to see if there is anything stuck on the wire that might be preventing contact with the wiper at one point.