Fuel Gauge always shows 1/4 full

[warwick-steve]

Another fuel gauge query! - can you help please

When I turn on the ignition my fuel gauge needle swings over to 1/4 full and stays there irrespective of how much fuel is in the tank.
As the gauge is not completely dead as it appears to be getting some current flow how do I go about identifying whether the gauge needs attention or the sender is stuck in one position? A new aluminium tank was fitted in 2011. The gauge has been like this since I bought the car 3 years ago and was a problem for the PO.The gauge is definitely earth connected.
Thank you for your help
Steve

 

[steveg]

Steve - see: https://tinyurl.com/y4pvkmzp - examine the sender orientation and whether you have a sunk float.

 

[warwick-steve]

Thanks Steve, will do
Steve

 

[warwick-steve]

Steve and others
A grovelling apology
Having put off this job to do other more urgent Healey tasks I forgot that I asked basically the same question some time ago and have the information you advised at the time, So sorry about that. A senior moment - again. No excuse now I will get down to resolving the problem.
Steve

 

[RDKeysor]

I pay attention to what Steve writes, and he writes a lot. My fuel instrument indicates full when it is full, but it registers empty with perhaps four gallons in the tank. It has a ground wire and the proper orientation. I carry a graduated dowel to check the tank but still ran out a few months back. Years ago I bought a sender with float from JCWhitney for a Volvo and found I could bend the float rod to reflect the actual (more or less) amount of fuel in the tank. I looked at that possibility on the Healey a couple of years back and found I couldn't do that on my car. Have forgotten why. All that I have read about the danger of tinkering with the delicate wires in the instrument itself has discouraged me from looking at that end of the system.

 

[Gliderman8]

I had the same problem on my TR6... fuel gauge always showed close to empty. I found the original plastic float was full of fuel making it sink to the bottom.
I ended up replacing it with a brass float (from a Ford Mustang) and I have not had a problem since.

 

[DTDuck]

Another fuel gauge query! - can you help please

When I turn on the ignition my fuel gauge needle swings over to 1/4 full and stays there irrespective of how much fuel is in the tank.
As the gauge is not completely dead as it appears to be getting some current flow how do I go about identifying whether the gauge needs attention or the sender is stuck in one position? A new aluminium tank was fitted in 2011. The gauge has been like this since I bought the car 3 years ago and was a problem for the PO.The gauge is definitely earth connected.
Thank you for your help
Steve

You can easily check the gauge to see if that is your problem. Connect a grounded wire to the sending unit side of the gauge. If your not sure which side it is use a test light to see which side is hot when the key is on (it will be the other side). When you have attached the grounded wire the gauge should read full when the switch is on. If it does, then the gauge is not the problem, the sending unit is.

Cheers,
Dan M.

 

[warwick-steve]

Thanks
Hope to get in the garage tomorrow to check this out
Steve

 

[steveg]

You can easily check the gauge to see if that is your problem. Connect a grounded wire to the sending unit side of the gauge. If your not sure which side it is use a test light to see which side is hot when the key is on (it will be the other side). When you have attached the grounded wire the gauge should read full when the switch is on. If it does, then the gauge is not the problem, the sending unit is.

Cheers,
Dan M.

If you can get a mirror up by the back of the gauge, you'll see one of the connections is labelled "T" as in Tank [sender]. The other is "B" for Battery.

 

[warwick-steve]

Hi again
I checked the gauge and is appears to be OK. I connected a ground wire to the T terminal and the needle indicated "empty". I disconnected the wire to the sender and the needle indicated "full".
Removing the sender looks like a problem. It appears the old sender was installed in the new tank and that a translucent silicone type sealant was used. I would be worried about cleaning up the sealing face before fitting the new sender ie how to prevent bits of silicone etc falling into the tank. Looks like I may have to keep the measuring dip stick
Anyone know whether the retaining screws screw into threaded inserts in the sealing face?
Thanks again for your advice
Steve

 

[John Turney]

Do you have a ground wire from the sender case to a good ground? The sender case may not be grounded with that silicone there.

 

[warwick-steve]

Hi John
Wouldn't I have the same situation with a gasket there? Actually not sure where the tank is grounded so will go and look.
If I do attempt to remove the sender I wonder if the silicone will peel off or whether I would end up picking at it with the danger of bits falling into the tank.
I will check the ground situation but if that doesn't help i'm inclined to keep using the measuring stick.
thanks
Steve

 

[steveg]

Original ground was via fuel line and hard connection to fuel pump. Easy to run a ground wire from top screw to chassis:

 

[John Turney]

Hi John
Wouldn't I have the same situation with a gasket there? Actually not sure where the tank is grounded so will go and look.
If I do attempt to remove the sender I wonder if the silicone will peel off or whether I would end up picking at it with the danger of bits falling into the tank.
I will check the ground situation but if that doesn't help i'm inclined to keep using the measuring stick.
thanks
Steve

Yes, the same could happen with the gasket, although the silicone could end up in the screw threads. As Steve points out, the ground should be through hard fuel lines. I had to add a grounding wire like Steve did.

As for silicone bits falling in the tank, that's a danger either way. How you solve that problem in the future is to apply the silicone to the sender and let it sit for a bit to "skin over" before screwing to the tank. That keeps it from sticking to the tank.

 

[warwick-steve]

Hi Steve and John
Thanks for that info and image - all really helpful. -I will check the earth connection.
cheers
Steve

 

[warwick-steve]

John
What is the blue fuel resistant sealant please
Steve

 

[steveg]

That's Hylomar. I also used bonded sealing washers and pan head screws for better distribution of pressure. 14 years later setup doesn't leak.

 

[Bob_Spidell]

John
What is the blue fuel resistant sealant please
Steve

I've used this stuff with good results:

https://www.amazon.com/Permatex-854...t=&hvlocphy=9032277&hvtargid=pla-571817582075

It feels and smells a lot like Hylomar. I have a BN2 with an aftermarket tank which has a poorly made sender flange; finally stopped the leaking with two cork gaskets with a thin smear of this.

 

[John Turney]

Bonded washers are a good thing.

 

[warwick-steve]

Interesting about the bonded washers. Thanks all for the latest info
Steve