66 Fuel Gauge Issue

[s2ms]

The fuel gauge in my 66 recently started acting weird, basically drops too fast, and no....not due to my right foot. For example, a few weeks ago it showed 1/4 full when I filled the tank which then showed full on startup.  Was surprised that it used a 1/4 tank on the 10 mile drive home. Drove it about 40 miles over the next couple weeks and again down to 1/4 tank. But when I filled the tank again it only took 4 gallons which is what I would have expected for that much driving, gauge now showing full again, then dropped another 1/4 on the same 10 mile drive home.

Does this sound more like a gauge or sender/float issue? Both sender and gauge are original.

Thanks,
Dave

[deathsled]

Mine does the same thing.  I got used to it and tend to ignore it as a result.  Now I will be curious to see the solution.

[trotrof1]

First check the connections at the back of fuel gauge and at the fuel sender. Make sure the ground is good at sending unit. If OK, I would inspect the sender to see if the wiper contact is worn out. You can put an ohm meter on the wire connection and move the float arm while observing any erratic nonlinear readings on a sweep test. Usually, the wiper arm fails a visual inspection.

[Rickmustang]

I think your fuel sender float has a hole and is filling with some amount of liquid. Easy fix. Happened to me as you describe.

[s2ms]

Thanks for the replies.

Was wondering about a ground issue too so will check that first. Also thought about a float hole but the gauge only drops when driving, seems stable when parked. Would a hole react like that?

If grounds look good I'll pull the sender and check that and the float. Been meaning to install the new gas tank anyway....

[Lincoln tech]

Thanks for the replies.

Was wondering about a ground issue too so will check that first. Also thought about a float hole but the gauge only drops when driving, seems stable when parked. Would a hole react like that?

If grounds look good I'll pull the sender and check that and the float. Been meaning to install the new gas tank anyway....

I would think if the float had a hole in it , it would fill with fuel and always read empty , if you're going to replace the fuel tank then replace the sender with it .

[KR500]

Thanks for the replies.

Was wondering about a ground issue too so will check that first. Also thought about a float hole but the gauge only drops when driving, seems stable when parked. Would a hole react like that?

If grounds look good I'll pull the sender and check that and the float. Been meaning to install the new gas tank anyway....

I would think if the float had a hole in it , it would fill with fuel and always read empty , if you're going to replace the fuel tank then replace the sender with it .

I have seen floats with a pin hole that have only been partially filled with fuel and make the gauge read goofy as they do not totally sink.

[trotrof1]

If you do end up pulling the sender out let us know your findings.

[6s2055]

Number of years back I had the same problem. The float also had developed pin hole. Just ended up replacing the sending unit.

[s2ms]

If you do end up pulling the sender out let us know your findings.

Will do.

The sender is original to the car so would like to have it rebuilt if possible. Any recommendations on someone who does that?

[trotrof1]

I was thinking the same thing. Maybe a replacement unit could be scavenged to renew the original. Has anyone out there been there done that?

[Bob Gaines]

I was thinking the same thing. Maybe a replacement unit could be scavenged to renew the original. Has anyone out there been there done that?

Of course only a original with a good face plate is worth any effort in saving.  I have done a few using donor repro parts but I do not recommend that approach. There are people that rebuild the units for a nominal fee which is a better alternative IMO.

[s2ms]

Of course only a original with a good face plate is worth any effort in saving.  I have done a few using donor repro parts but I do not recommend that approach. There are people that rebuild the units for a nominal fee which is a better alternative IMO.

Thanks Bob, any recommendations on who can rebuild these? My original looks in nice shape, externally anyway...

[6s1640]

Hi Dave,

I will store your fuel in my gas tank?  I will come down and help you.  LOL

Cory

[Bob Gaines]

Of course only a original with a good face plate is worth any effort in saving.  I have done a few using donor repro parts but I do not recommend that approach. There are people that rebuild the units for a nominal fee which is a better alternative IMO.

Thanks Bob, any recommendations on who can rebuild these? My original looks in nice shape, externally anyway...

Try this guy.     https://desertclassicparts.com/fuel-sending-unit-rebuilding-service/