MGB: FUEL GAUGE ON FULL

We fixed the the new leaking sending unit by replacing the gasket. Thank you for the advice.
The gauge jumps to full when the ignition is turned on. I know the tank is about half full.
Checked the wire connections on the sending unit and gauge with a voltmeter. All seems ok and the sending unit appears to be in working order.
The Jaeger gauge was recently checked and I am told is ok.
So why does it always read full?
My 61A is converted to negative earth.
Your help and advice would be appreciated as always.
Cheers
Johan

I suggest a faulty sender.

Faulty sending unit, or bad ground at the tank.

If this is a "new" unit they are garbage and fail often.

You can check this a couple of ways.

To check the ground just ground the sending unit to the chassis and see if the gauge reads correctly, if it does then the tank isn't grounded. To check the sending unit you can drain the tank and remove the sending unit and leave it connected. Move the float up and down and if the sender is OK the gauge will move.

You can test the sender's wire by removing it from the unit and grounding it to the body. If the gauge reads empty the wiring in the car is OK and it, again, is probably the sender.

You can also remove the cover on the sender and verify that the wire inside is not broken (which I suspect it is). If this wire is broken you will read Full all the time.

HTH and good luck.

BTW -- if you have an original unit these guys can fix it:

http://www.nisonger.com/

Cheers,
Christopher

Thank you.
Yes, this is a new unit. Actually the second new unit. On the first one the float had a leak, filled up with gas and sank. Had it replaced. This one leaked through the back gasket. Replaced the gasket and stopped the leaking.
I complained to Moss. They claim they have received very few complaints about this unit. I suggested to them that they check MGE.
On this unit we put a wire connecting it to the chassis. I'll check to see if it is making contact and follow your advice.
Hopefully I don't have to get a third new unit.
Cheers
Johan

"But I can't be overdrawn - there are still checks in the checkbook!" It sounds like your sending unit is blonde.

Johan,

If it is the sending unit (I'm betting it is) you'd be much better off finding an original sending unit and having it rebuilt. Otherwise you will keep running into the same problems.

These replacements simply do not last.

Also, when you install the unit make sure you use a material like hylomar to seal the gaskets.

Cheers,
Christopher

take sending unit out and exercise it and watch gage. make sure you grond it
if you have half tank you will haver to jack up that side or drain it. disconnecr battery while removing

OK - not sure if anyone can help with this or not. Our car didn't have a gas tank with it, so I have no idea what the original parts look like vs. the aftermarket.

I am looking at an "original" gas tank on ebay, and it has a pretty clear image of the fuel sending unit. Can anyone tell me if this looks like an original sending unit or not? Based on the problems everyone seems to have with the reproduction units, I would rather buy an original if I can find one.

Thanks in advance :D

That appears to be an original unit.

If possible get some pics of the wire on the inside and verify that the float doesn't leak.

Cheers,
Christopher

Thanks for the speedy response Christopher! I have requested the information from the seller - so we'll see what happens now...

Hello
I had the same problem. This fix is fairly easy. The issue is that the sender grounds through the pivot point to the sender body. This connection is dicey at best. You clean up the sender arm and solder a piece of wire to it. Attach the other end to the sender body with a self tapping screw. Problem solved.
Found this in Mike Ash's book which is a collection of technical articles.

Great idea Doug, my connection is a bit iffy as well.

Simple yet effect solution, thanks for bringing it forward

Bruce

no worries Bruce. I'm not taking credit though. Somebody sent this to Mike Ash who does the technical column in the NAMGAR newsletter.
By the way, I know your brother Dan very well through the Miata club

Miata.... well not as pretty as an MGA but it does get the job done.

Pretty hot machine he has. I took my son out for a ride, and he was speechless, lol. I guess, it's one of the reasons I got interested in MGA s.

Leslie,

This is an original sending unit, hope it may help!!!