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Fuel Tank

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WGM1980MGB Avatar
WGM1980MGB Wayne Melton
Alpharetta, GA, USA   USA
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1972 MG MGB "Sudden Impact"
1974 MG MGB "Back On The Horse"
1980 MG MGB "Third Time's A Charm"
I have a 1980 MGB that has what appears to be a new fuel tank on it. I can never get the quage to register full even though gas runs out the filler hose each time. Is this a problem with the guage or the tank having too much back pressure to actual accept the fuel?

I was under the car on a lift while getting the oil changed and I asked the mechanic about it. He pointed to a "vent" on the upper right side. He said it had been painted over. Does that mean there should be an actual vent hole for the pressure to escape and maybe its been painted over?

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bkowitz Avatar
bkowitz Brad K
San Diego, CA, USA   USA
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1975 MG MGB
I've got the same problem. I tried installing a new fuel sending unit and my gauge still doesn't read past 3/4 tank when full. Curious to hear what some possible causes might be.

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Fogliner Avatar
Fogliner Mark Vanherd
Port Clements, BC, Canada   CAN
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1974 MG MGB
I came across this in a search.

http://www.mgexp.com/phorum/read.php?1,473820,473928#msg-473928

Kind Regards

Mark

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Basil Adams Avatar
About 12 miles from Sears Point, CA, USA   USA
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I am unsure what may be causing your failures but I have a supplier that has stopped carrying the aftermarket sending units. They claim that 50% of them came back within a year. They now only sell the UK-made ones made by the original manufacturer (actually the company that made them for Smith's). Let me know if it's worth it to try a better sender. Thanks. Basil 707.762.0974 basiladams@yahoo.com



Basil C. Adams
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Gokart Avatar
Gokart Rob Illingworth
Palmerston North, Manawatu, New Zealand   NZL
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1974 MG MGB GT
2004 MG ZR 160 "SCRUFFY"
Guys,

Makes sence to calibrate them, esp new ones as per the above link. The sender works obviously otherwise you would not get any reading, it just needs to be set correctly.

Do the new ones come with calibrating instructions?

Please let us now if the calibrating works.

Cheers Rob.



Cheers Rob

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purdysmg Avatar
purdysmg John Harrison
Gjettum, oslo, Norway   NOR
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1971 Morgan 4-4 "Pretend Norton"
1971 Morgan 4/4
1978 MG MGB "Topless Go Go Girl"
Easy to test just remove the wire at sender then touch to a good solid ground and see if the dash gauge reads full. If not then it is a dash gauge issue. If it reads full then it is the internal float or sender unit itself.

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OurB75 Avatar
OurB75 Dave Hughes
Bowmanville, ON, Canada   CAN
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1974 MG MGB GT "Sweetheart"
1975 MG MGB MkIII "OURB"
1990 Mazda MX-5
When I had this problem, we found a pin hole in the fuel sender float. As the float was 1/2 full of fuel the gauge always ready incorrectly


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chris Avatar
chris Chris Roop (RIP)
Pendleton, OR, USA   USA
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In reply to # 2755253 by WGM1980MGB I have a 1980 MGB that has what appears to be a new fuel tank on it. I can never get the quage to register full even though gas runs out the filler hose each time. Is this a problem with the guage or the tank having too much back pressure to actual accept the fuel?

I was under the car on a lift while getting the oil changed and I asked the mechanic about it. He pointed to a "vent" on the upper right side. He said it had been painted over. Does that mean there should be an actual vent hole for the pressure to escape and maybe its been painted over?

Inside your trunk on the right side, you should have an evaporative can (stock color is silver). A hose should run from that to the vent hole on the top right rear of your tank, right around the filler neck. If that is plugged off, you would have to have a vented gas cap to keep your car running.
Whether or not your tank vent system is plugged, you should still be able to fill the tank all the way up; if you have gas running out, you are full.
So, your best bet would be to do the test posted by purdysmg, and once you have determined that it is the sender, pull it and calibrate as per Fogliner's link. Do check the float for a leak as mentioned.

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bpmichaud Avatar
bpmichaud Brian Michaud
Corcoran, MN, USA   USA
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1979 MG MGB
Read post #9 from Kelvin who works for Moss. if you have one of these tanks it could be the source of the problem. It is for me. You have to nurse it a little bit to get it full.
Brian

http://www.mgexp.com/phorum/read.php?1,1889235,1889235#msg-1889235



Brian.
79 mgb
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bpmichaud

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