• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Fuel Level Sending Unit

Share this page

C

chuggy

Freshman Member
Offline
I recently filled up my car and now the fuel gauge indicator seems to be stuck on full even though i have now done 200 miles. Is it relatively easy to change the sending unit on the side of the tank and do you have to drain it?
How many miles roughly would you get to a tank of gas?
 
Measure the resistance of the sender at full and again at empty. If there is no change, it's stuck. If there is a change, the problem most likely lies in the wiring or in the gauge itself. Also make sure you're getting 10 volts at the gauge.

Depending on your miles per gallon, you should get between 250 and 350 miles from a tank of fuel. 1966-mid 70's cars also had a couple gallons more than the late models.
 
Steve, what year did they start putting that can in the tank? Also, do you know if the new tanks have it? PJ
 
In 1970 they installed an expansion chamber which reduced the capacity of the tank by two gallons, down to 12. Earlier bolt-on tanks were 14 gallons.
 
Before buying any new parts, go to the back side of your fuel gauge and disconnect the green/black wire which goes from the gauge to the sending unit. Temporarily hook up a jumper wire to that lug on the gauge. Switch on the ignition and the gauge should read empty. Ground your jumper wire and the gauge should go to full. This indicates that the gauge is OK. Switch off the ignition and re-connect the green/black wire.

Repeat this test at the sending unit by disconnecting the green/black wire there. If with gauge reads full with the green/black wire disconnected, it indicates a short to ground somewhere along the green/black wire. If the gauge operates as in the first test, it indicates a problem in the sending unit.
 
Back
Top