Fuel gage bounces
Thread Starter
Racer
Joined: Jul 2009
Posts: 336
Likes: 1
From: Asheville N.C.
Ed I missed your thread yesterday for some reason. I think at this point since the gauge is out it might be best to send your gauge to Willcox and let him test it.
I had one something like this in a 71. New tank,new aftermarket sender and a new aftermarket gauge. The gauge was foreign and was the type that "did not" use the resistor across the back of the gauge. Ended up having the original gauge rebuilt and replacing the sender with either an AC or one from Quantas (can't remember which one ). This fixed the problem. This doesnt help you but I did recognize a difference between a very fast needle that follows every move of the sender and a needle that flicks back and forth between E and F. The flicking is one problem and the very fast needle is another. Recognizing the difference is important.
The "improved ground" that Noonie mentioned has me wondering if a semi-poor ground could hide a gauge with poor dampening.I'm going to the garage and will attach a variable pot on the ground side of the gauge and see if this will drastically effect the accuracy of the gauge. If this wont effect the accuracy then its possible it can mask a bad gauge.
( Ernie I will have to cut into the series of pots to control both sides but I'll put it back.
)
I had one something like this in a 71. New tank,new aftermarket sender and a new aftermarket gauge. The gauge was foreign and was the type that "did not" use the resistor across the back of the gauge. Ended up having the original gauge rebuilt and replacing the sender with either an AC or one from Quantas (can't remember which one ). This fixed the problem. This doesnt help you but I did recognize a difference between a very fast needle that follows every move of the sender and a needle that flicks back and forth between E and F. The flicking is one problem and the very fast needle is another. Recognizing the difference is important.
The "improved ground" that Noonie mentioned has me wondering if a semi-poor ground could hide a gauge with poor dampening.I'm going to the garage and will attach a variable pot on the ground side of the gauge and see if this will drastically effect the accuracy of the gauge. If this wont effect the accuracy then its possible it can mask a bad gauge.
( Ernie I will have to cut into the series of pots to control both sides but I'll put it back.
)Well at this time I'm really thinking about R&R the sending unit
because I don't know what else to do (but still thinking) and have to start somewhere. I just hate to throw good money away when it can be used somewhere else.
Thanks again ED
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
I wish we could isolate the problem to either the gauge or the sender. If you want to spend a couple bucks you could go to Radio Shack and get a potentiometer to take the place of the sender in the tank and control the dash gauge from the rear deck and watch the dash gauge through the back window and see if it reacts the same. Just a thought.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Safety Car
Joined: Apr 2000
Posts: 3,802
Likes: 61
From: Wichita KS
FWIW, I had a fuel gauge that bounced a lot on my '65 and it turned out to be one of the ribbon cables on the sending unit. It was holding on by a thread having rusted through 99% of the metal. As the gas moved in the tank so did the ribbon cable varying the amount of voltage that was transmitted to the gauge.
cc
cc
Thread Starter
Racer
Joined: Jul 2009
Posts: 336
Likes: 1
From: Asheville N.C.
FWIW, I had a fuel gauge that bounced a lot on my '65 and it turned out to be one of the ribbon cables on the sending unit. It was holding on by a thread having rusted through 99% of the metal. As the gas moved in the tank so did the ribbon cable varying the amount of voltage that was transmitted to the gauge.
cc
cc
I was wondering myself if there could be sometype of connection break down inside the tank on the sender and that was why I was thinking of pulling it to check. So at this point I may go to Radio Shack per DW and see what I can find to check it on the tank.
Thanks again to both
ED
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
OK I found something. I set a gauge up and using the pot setup Ernie sent me I set the needle to 1/2 tank- full power on the 12 volts in to the gauge-- full and solid ground to the gauge cluster
Then I removed the ground (same as the ground to the tank) and put a pot in between the gauge and ground so I could vary the ground.
I then rotated the ground pot up to 50 ohms-this only changed the needle by 1/8 tank so this wont effect the accuracy too bad.
Then using the first pot that varys the input to the gauge (what comes from the tank sender) I started rotating it back and forth to make the needle go from E to F.
With the resistance up on the ground side the speed of the needle is much much slower.
To me this means a poor ground at the tank sender can mask a bad gauge."Bad" gauge from the standpoint of dampening even though it reads accurately.
My thoughts are Noonies gauge has poor dampening capability's but probably reads accurately sitting still but when he soldered the ground in made a better connection to ground and increased the sensitivity of the gauge movement.
Then I removed the ground (same as the ground to the tank) and put a pot in between the gauge and ground so I could vary the ground.
I then rotated the ground pot up to 50 ohms-this only changed the needle by 1/8 tank so this wont effect the accuracy too bad.
Then using the first pot that varys the input to the gauge (what comes from the tank sender) I started rotating it back and forth to make the needle go from E to F.
With the resistance up on the ground side the speed of the needle is much much slower.
To me this means a poor ground at the tank sender can mask a bad gauge."Bad" gauge from the standpoint of dampening even though it reads accurately.
My thoughts are Noonies gauge has poor dampening capability's but probably reads accurately sitting still but when he soldered the ground in made a better connection to ground and increased the sensitivity of the gauge movement.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Ed do you still have the gauge out of the car ? If you have put it back in it would be great if you could go to the Shack and get a variable pot and put it between ground wire at the tank and the sender. Dial it up and see if that slows down the needle bouncing. If it does it might explain some things.
Thread Starter
Racer
Joined: Jul 2009
Posts: 336
Likes: 1
From: Asheville N.C.
Ed do you still have the gauge out of the car ? If you have put it back in it would be great if you could go to the Shack and get a variable pot and put it between ground wire at the tank and the sender. Dial it up and see if that slows down the needle bouncing. If it does it might explain some things.
Retested it again with pot and no movement. Can I now assume that it is the sender that's bad??????????
ED
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Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
Let me get this straight. You put the pot between the sender wire and the ground wire at the tank ? In other words bypassing the tank unit. If so that is taking the place of the sender in the tank so rocking the car would not change anything.
If this is how you hooked up the pot try rotating the **** back and forth quickly and watch the needle and see if it follows smoothly or is bouncy. If its bouncy the problem is going to be in the gauge.
If this is how you hooked up the pot try rotating the **** back and forth quickly and watch the needle and see if it follows smoothly or is bouncy. If its bouncy the problem is going to be in the gauge.
Thread Starter
Racer
Joined: Jul 2009
Posts: 336
Likes: 1
From: Asheville N.C.
Let me get this straight. You put the pot between the sender wire and the ground wire at the tank ? In other words bypassing the tank unit. If so that is taking the place of the sender in the tank so rocking the car would not change anything.
If this is how you hooked up the pot try rotating the **** back and forth quickly and watch the needle and see if it follows smoothly or is bouncy. If its bouncy the problem is going to be in the gauge.
If this is how you hooked up the pot try rotating the **** back and forth quickly and watch the needle and see if it follows smoothly or is bouncy. If its bouncy the problem is going to be in the gauge.
ED
Thread Starter
Racer
Joined: Jul 2009
Posts: 336
Likes: 1
From: Asheville N.C.
As mentioned, the sending unit is on the workbench. When doing this float test with the ohm meter, as I raise the float slowly I see some up and down readings as I continue up (Not using the POT on the bench test at this time) which could be causing the fuel gauge to bounce from these readings? I agree with you that it should be smooth and it's not, does this raise an eyebrow that we should continue testing or consider a sending unit? Just a thought......Don't give up on me!!!!! ED
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
Thanks again DW
As mentioned, the sending unit is on the workbench. When doing this float test with the ohm meter, as I raise the float slowly I see some up and down readings as I continue up (Not using the POT on the bench test at this time) which could be causing the fuel gauge to bounce from these readings? I agree with you that it should be smooth and it's not, does this raise an eyebrow that we should continue testing or consider a sending unit? Just a thought......Don't give up on me!!!!! ED
As mentioned, the sending unit is on the workbench. When doing this float test with the ohm meter, as I raise the float slowly I see some up and down readings as I continue up (Not using the POT on the bench test at this time) which could be causing the fuel gauge to bounce from these readings? I agree with you that it should be smooth and it's not, does this raise an eyebrow that we should continue testing or consider a sending unit? Just a thought......Don't give up on me!!!!! ED
I wonder if it would test any different when its in fuel ?
When I mentioned getting your leads closer to the pot I actually was referring to the rheostat or pot in the sending unit (not sure what the correct name is for it ).
What readings you are getting ? We know somewhere between 0-90 is what it should read. Can you describe your readings ? For instance 0 5 10 15 20 "90" 40 50 ? Or and this is the one I suspect 0 5 10 15 20 175 40 50 ? The 175 reading will drive the needle crazy.
Thread Starter
Racer
Joined: Jul 2009
Posts: 336
Likes: 1
From: Asheville N.C.
Definitely not giving up,its just starting to get fun.
I wonder if it would test any different when its in fuel ?
When I mentioned getting your leads closer to the pot I actually was referring to the rheostat or pot in the sending unit (not sure what the correct name is for it ).
What readings you are getting ? We know somewhere between 0-90 is what it should read. Can you describe your readings ? For instance 0 5 10 15 20 "90" 40 50 ? Or and this is the one I suspect 0 5 10 15 20 175 40 50 ? The 175 reading will drive the needle crazy.
I wonder if it would test any different when its in fuel ?
When I mentioned getting your leads closer to the pot I actually was referring to the rheostat or pot in the sending unit (not sure what the correct name is for it ).
What readings you are getting ? We know somewhere between 0-90 is what it should read. Can you describe your readings ? For instance 0 5 10 15 20 "90" 40 50 ? Or and this is the one I suspect 0 5 10 15 20 175 40 50 ? The 175 reading will drive the needle crazy.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Have you tried hooking the sending unit up to the car wiring outside the tank and operating it and watching the needle ?
Then you can hook the Shack pot up and do the same and see if there is a difference.
I'm leaning towards the gauge being the bouncing problem at this point.
Then you can hook the Shack pot up and do the same and see if there is a difference.
I'm leaning towards the gauge being the bouncing problem at this point.
Thread Starter
Racer
Joined: Jul 2009
Posts: 336
Likes: 1
From: Asheville N.C.
Have you tried hooking the sending unit up to the car wiring outside the tank and operating it and watching the needle ?
Then you can hook the Shack pot up and do the same and see if there is a difference.
I'm leaning towards the gauge being the bouncing problem at this point.
Then you can hook the Shack pot up and do the same and see if there is a difference.
I'm leaning towards the gauge being the bouncing problem at this point.
Thanks again ED
Will update when it's fixed. Again thanks
ED
Former Vendor
Joined: Aug 2006
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From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Hey Ed and Roger..
I'll try to look this over tomorrow and see if I can help.
Ed, if you have the gauge out and want to send it to me, I (my shop, right now I can't do diddle) can test it in about 5 minutes. No charge!
Let me look this entire thread over and I'll try to post again tomorrow. Don't go spending money unless you need to!
Willcox
I'll try to look this over tomorrow and see if I can help.
Ed, if you have the gauge out and want to send it to me, I (my shop, right now I can't do diddle) can test it in about 5 minutes. No charge!
Let me look this entire thread over and I'll try to post again tomorrow. Don't go spending money unless you need to!
Willcox
Last edited by Willcox Corvette; Sep 4, 2009 at 08:52 AM.
Advanced
Joined: Jul 2007
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From: Lake Arrowhead CA
[QUOTEcan test it in about 5 minutes. No charge! But let me look this entire thread over and I'll try to post again tomorrow.
Willcox
][/QUOTE]
With respect to other vendors, this is why I buy from wilcox
Willcox
][/QUOTE]
With respect to other vendors, this is why I buy from wilcox