Fuel gauge sending unit
 

Beautiful day here in the Seattle area. Clear skies, cold but no rain. So I drove the 76 911S to work. Fuel gauge showed some gas. Last fill up with 92 ethonal free was in July of this year so I knew there wasn't a full tank. Just as I arrived, I ran out of gas. No worries. Got a two gallons in the tank and she fired right up. But the fuel gauge shows half a tank.

The sending unit is new. Is this typical of the fuel sending units to be "not accurate" just close to accurate? My 71 MGB fuel gauge is "not accurate" either.

Any thoughts on this are appreciated.

Michael.

when you say sending unit you mean the float in the tank? it's all one unit as I recall.

I go by the odometer

What make of sender did you get?

Yes, I mean the float in the tank. I purchased one from Pelican a few years back. I don't know the make.

I recall some saying that the URo brand replacement was or can be wonky. My ‘77 gauge will fluctuate on turns or stops and not wind up in the same spot all the time, levels off after driving awhile I guess once the gasoline settles down. Thought of replacing the sending unit, I cleaned up the ground and connection on both dash gauge and tank sender and seems to work properly for now. As for accuracy, I can’t be exactly sure.

Oddly too for gauge accuracy… is after I check my engine oil (while idling) the dash gauge will indicate all the way to the top after I return the dipstick, even though the oil level is below half indentation mark. Thought here may be the oil dipstick interferes with the float sender, whereas in your case the (your) gas tank sender float might be (if possible) installed incorrect ?

My URO fuel level sensor has always a little off. I have learned to "work with it".

The 1st 1/2 tank is slow and the last 1/2 is fast. Driving in remote areas, I need to be a little mindful to fill up when it gets around the 1/2 tank mark.

Although, the sensor seems to be fairly accurate when the tank gets below 1/4 tank. The empty tank light comes on with just over 1 imperial gallon remaining. I rarely get that low - only when I have to stretch things to get to a non-ethanol gas station.

Thanks for all the input. I can live with it. I have two modern cars; one less modern is a joy. :)

I’m reasonably sure mine is a URO and it’s wonky.

I’m replacing the tank soon and this time I’m trying the Dansk.

When I replaced mine, with a URO, I measured the resistance to verify full scale operation and low fuel level. It worked perfectly, but after installation my gauge would only read down to ~1/4 tank. What I have since found is that my level sensor to fuel gauge signal wire has higher than normal resistance. So my next move will be to address the connections or just run new wire. But like others have said, until then, I just pay attention to my miles and know that my low fuel level light does function correctly.

Best of luck with yours.

Great tip, TxGerman!

I free-ed up my float by running a rag on a coat hanger, soaked with Marvel Mystery Oil.

I rode most of the day with the gauge reading half full.
...Pulled off the interstate and the low fuel warning light came on.
The float was hung up in the middle of the tube.

Just a suggestion before you do anything drastic.

Bill K

Thanks guys, reported to Engineering. Please don't hesitate to PM any feedback.