Technical Gas guage

Ok, I need some help. My gas gauge is pegged out all the time above full. Dropped tank and checked wires. The ground is good and I have partial continuity on the gauge wire. Is this right or should the gauge wire have none until ran thru the sending unit????

 

With the feed wire unhooked your gage should read full.

Here's a great checklist for you to work with.

http://www.sailmagazine.com/diy/engines/test-replace-fuel-gauge-sending-unit/


Sent from my iPhone using The H.A.M.B. mobile app

 

That link will work but a car is usually going to have a different ground than a sailboat will .

Pat did you check the sending unit with an ohm meter to see if it has the right resistance and the resistance changes though the swing of the float arm?
Is there a good ground connection from the body of the sender to the ch***is or body? That is quite often the issue especially if you put a layer of rubber or other material between the tank and the frame and the straps.

 

It is grounded good. The gauge reads all the way over past full. Every now and then, more then than now, it will work. It worked fine for 19 years and then started this. I guess I will have to pull the sender and see if it is working with a meter. If the sender wire was grounding somewhere between the gauge and sender would this show the same reading? It is pegged above full and normally never goes that high.

 

10 years not19.

 

what kind of car is it? for example, Ford gas gauges behave the opposite of GMs when the wire is shorted or open.

 

32 Ford VDO gauges. Am I correct that if I ground the sending unit wire at the sender, the gauge should go to empty?

 

If it does not move, either the gauge is bad or there is a break in the sender wire?

 

VDO is 10 ohms empty, 180 ohms full. So if you ground the sender wire, it might go past empty. Or damage the gauge?

If the sender wire or sender is open circuit, it should read past full.

Make sure the gauge ground is connected, and the sender is grounded.

 

I pulled the sending unit wire off the gauge and touched it to the grounding lug and gauge went to zero. Looks like it is time for a new sending unit....

 

When I removed the wire, it went right back to the full side pegged. Time to pull the tank again. Thank you guys for your input!!