Fuel gauge and sending unit

[TR7Aaron]

Hi all,
The fuel gauge in my 1976 hasn't worked (always reads empty) since I bought the car so I tried fixing it today. When I remove the green wire (bottom-most connector) from the sending unit and ground it to the chassis, the gauge goes to full, so I'm assuming the gauge is OK, but the sending unit is broken. I've read the archives regarding this, and past postings seem to confirm this.
I thought I would save some money and swap the sending unit from my parts car 1980 to the '76, but after reading my VB
catalog, they show the 1975 & 1976 cars take a different sending unit that is about 5 times the cost of the 1977 - up years! Any one know what the difference(s) are and would it be possible to use a sending unit from a 1980 on a 1976?
Thanks again in advance!
Aaron



Relax, all right? My old man is a television repairman, he's got this ultimate set of tools. I can fix it.

[busheytrader]

Hi Aaron,

I thought the fuel tanks and sender units for the carb equipped 7's remained unchanged throughout the production run.

This link is off the Rimmers website and there's no mention of different items for different production years. Have you removed the sender unit from your parts car and connected it up to the loom on your '76 to see if it works?

http://www.rimmerbros.co.uk/rimmer/tr7/ ... 20Fittings

Adam

TR7 V8 DHC Jaguar Solent Blue. 9.35cr Range Rover V8, Holley 390cfm, JWR Dual Port, 214 Cam, Lumention, Tubular Manifolds, Single Pipe Exh, 3.08 Rear, 200lb Spax & Solid Bushes, Anti- Dive, Granada Vented Discs & Calipers, Braided Hoses, Green Stuff, 4 Speed Rear Cylinders, Uprated Master Cylinder & Servo, AT 5 Spokes and Cruise Lights. No Door Stickers. Mine since July 1986, V8 from 1991

[Underdog]

Yes, Rimmer only show TR7 And TR8. I wouldn't put much stock in VB. I've found them wrong before. Interestingly, Rimmer catatlog doesn't show the fuel injected unit. However, the # they give for TR8 matches the TR7 fuel injection # in TRF catalog. Makes sence as they both have pumps in the tank.

72 MGB BRG
80 TR8 Persian Aqua
If women don't find you handsome, they should at least find you handy.

[windy one]

Didja chek the wiring back to the sending unit and its connections. Corroded terminals, not a faulty unit, have almost always been my culpret on these cars. Just my .02cents

Johnny

[V8Wedgehead]

Sounds like you have a float full of gas for the sending unit. You might want o drain the tank and pull the unit to see if it gas ridden! easy fix is to sit the float out in the sun and let the gas evaporate and reinstall it. If your not driving the car then pull the unit out and it is possible if the gas was ever low the arm for the float could be corroded so it will not move upward and read empty all the time.

Michael
1980 TR8 FHC/Works Rally Project

If it is broken then fix it....if it is not then make it faster!"

[TR7Aaron]

Do TR7 gas tanks have convenient drain plugs or do I get to take a gasoline bath trying to drain it?
Aaron



Relax, all right? My old man is a television repairman, he's got this ultimate set of tools. I can fix it.

[Hasbeen]

No, no drain plug Aaron, but the rubber hose, going to the fuel pump
is lower than the bottom of the fuel tank. Once there is fuel in the
hose, if you pull it off the pump, the fuel will siphon out of the
tank, until it is almost empty. It's a little hard to get it to a
container, but I'm sure you will find a way.

As the sender goes into a hole in the centre of the front of the
tank, you only need to get it down to about 1/3 to pull the sender,
with no flood of petrol.

I'm with windy one here. I have found most gauge problems have been
caused by bad connections, not the sender itself, although, I did
have one with the float about 15% full of petrol.

Don't expect too much from the fuel gauge even when working. None of
my 7s, or the 8 have ever read much above 3/4, no matter how full
the tank.

Hasbeen

[TR7Aaron]

Thanks for all of the advice, guys, especially about draining the tank through the pump end of the fuel line - that'll save me from making too big of a mess.
I think I may be missing something here. I pulled the green wire connector off the sending unit and grounded it. The gauge then went to the full (4/4) mark. Doesn't that signify that the wiring and gauge are OK?
I did remove and clean up all of the connectors but the gauge didn't react. Only when I ground the green wire do I get any gauge movement at all.
I'm also thankful that the sending unit is accessible without removing the tank. I've removed several gas tanks from other cars and it's always a balancing act and usually a mess.
Aaron



Relax, all right? My old man is a television repairman, he's got this ultimate set of tools. I can fix it.

[nervousnewowner]

aaron i got the opposite problem, my tank is permanently reading full...... once the car is on the road this will def be my first jobs to do list,..... i hate running out of petrol.....lol


the project at birth, watch it evolve...I hope...

[paul w]

Yup,i had this with the Grinnall recently.Cleaned the contacts at the sender
and all ok now.

See ya. Paul

[cliff]

Aaron, Disconnect fuel line at fuel pump as previously stated. Place open end on line over a suitable container, remove gas cap, wrap a shop towel around your airhose nozzle. Apply just enough pressure to get the fuel flowing, remove air source and monitor fuel drain until empty. Just another option. It worked for me. Luck..

Cliff[8D]

Don't use force, get a bigger hammer!!