Author Topic: 66 Fuel Gauge Issue  (Read 2890 times)

s2ms

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66 Fuel Gauge Issue
« on: March 08, 2023, 01:34:36 PM »
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
Dave - 6S1757

deathsled

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Re: 66 Fuel Gauge Issue
« Reply #1 on: March 08, 2023, 02:03:18 PM »
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.
"Low she sits on five spoke wheels
Small block eight so live she feels
There she's parked beside the curb
Engine revving to disturb
She's the princess from his past
Red paint gold stripes damned she's fast"

trotrof1

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Re: 66 Fuel Gauge Issue
« Reply #2 on: March 08, 2023, 02:14:55 PM »
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

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Re: 66 Fuel Gauge Issue
« Reply #3 on: March 08, 2023, 04:24:46 PM »
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.
1965 G.T. 350
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s2ms

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Re: 66 Fuel Gauge Issue
« Reply #4 on: March 08, 2023, 05:17:21 PM »
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....

Dave - 6S1757

Lincoln tech

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Re: 66 Fuel Gauge Issue
« Reply #5 on: March 08, 2023, 05:41:29 PM »
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

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Re: 66 Fuel Gauge Issue
« Reply #6 on: March 08, 2023, 06:40:22 PM »
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.
Rodney Harrold,Ohio SAAC Rep,SAAC 68 Shelby Concourse Judge,68 GT500KR 02267

trotrof1

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Re: 66 Fuel Gauge Issue
« Reply #7 on: March 08, 2023, 06:51:05 PM »
If you do end up pulling the sender out let us know your findings.

6s2055

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Re: 66 Fuel Gauge Issue
« Reply #8 on: March 08, 2023, 07:23:43 PM »
Number of years back I had the same problem. The float also had developed pin hole. Just ended up replacing the sending unit.

s2ms

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Re: 66 Fuel Gauge Issue
« Reply #9 on: March 08, 2023, 08:07:39 PM »
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?
Dave - 6S1757

trotrof1

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Re: 66 Fuel Gauge Issue
« Reply #10 on: March 08, 2023, 08:41:18 PM »
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

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Re: 66 Fuel Gauge Issue
« Reply #11 on: March 08, 2023, 08:50:12 PM »
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.
Bob Gaines,Shelby Enthusiast, Shelby Collector , Shelby Concours judge SAAC,MCA,Mid America Shelby

s2ms

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Re: 66 Fuel Gauge Issue
« Reply #12 on: March 08, 2023, 11:50:08 PM »
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...
Dave - 6S1757

6s1640

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Re: 66 Fuel Gauge Issue
« Reply #13 on: March 08, 2023, 11:51:23 PM »
Hi Dave,

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

Cory

Bob Gaines

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Re: 66 Fuel Gauge Issue
« Reply #14 on: March 09, 2023, 12:06:00 AM »
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/
Bob Gaines,Shelby Enthusiast, Shelby Collector , Shelby Concours judge SAAC,MCA,Mid America Shelby