Fuel Gauge Problems?
Thread Starter
Intermediate
Joined: Dec 2005
Posts: 33
Likes: 0
From: Baton Rouge LA
Fuel Gauge Problems?
Hi,
I just bought a 1993 and I have filled the tank twice and I've noticed that it stays on the full mark for a long time and then all of the sudden it's reading near a 1/2 tank full and it's really close to empty. Would this be a bad fuel tank sender or what?
Hope someone can enlighten me how to check this out, for sender/fuel pump units are expensive.
Thanks,
John
I just bought a 1993 and I have filled the tank twice and I've noticed that it stays on the full mark for a long time and then all of the sudden it's reading near a 1/2 tank full and it's really close to empty. Would this be a bad fuel tank sender or what?
Hope someone can enlighten me how to check this out, for sender/fuel pump units are expensive.
Thanks,
John
Melting Slicks
Joined: Oct 2002
Posts: 3,193
Likes: 1
From: Cincinnati Oh
the fuel sender unit has a simple rheostat built in - either the "float" is hanging up and catching on something IN the tank, or the rheostat (in-tank) is corroded and not sending out the proper resistance. Finally, the wiring to the dash could be faulty.
Based on your symptoms, I would gander that you need to take some brake cleaner to the in-tank rheostat.
Based on your symptoms, I would gander that you need to take some brake cleaner to the in-tank rheostat.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
Actually under normal operation the fuel gauge stays high for a long time however your situation may be a little worse. If you remove the tank unit you can use some fine emory cloth or sand paper to clean up the float unit wipers and coil wire contacts. I would first measure it to see if the resistance is smooth when moved.
My fuel gauge was an absolute mess, no bodys could be worse. I found out after I bought the car that it had been sitting for almost 2 years and probably with low fuel where the fuel did not cover the sending unit. It was real nasty took me hours to fix. I actually ran out of gas on the way home from the dealer. Thats how it knew it was really a 20 gallon tank.
I have a thread with some detailed information on the fuel gauge and how to make it read more accurate.
http://forums.corvetteforum.com/show....php?t=1373669
My fuel gauge was an absolute mess, no bodys could be worse. I found out after I bought the car that it had been sitting for almost 2 years and probably with low fuel where the fuel did not cover the sending unit. It was real nasty took me hours to fix. I actually ran out of gas on the way home from the dealer. Thats how it knew it was really a 20 gallon tank.
I have a thread with some detailed information on the fuel gauge and how to make it read more accurate.
http://forums.corvetteforum.com/show....php?t=1373669
Last edited by pcolt94; May 22, 2006 at 06:38 AM.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
High sulphur content in fuels seems to be the popular culprit for bum gas gages and the last Google Search I did for "Bad Gas" had Shell Oil on the losing end of most of the Class Action Lawsuits that have been brought over this issue. They did mix up a particularly gnarly batch at one of your Gulf Plants that found it's way to Florida about two Years ago and one of our members got them to spring for a new sender. You might see if anything is going on in your Area, particularly if you use Shell gas.
Safety Car
Joined: Feb 1999
Posts: 3,504
Likes: 4
From: Mexico Beach FL
There are several factors at work here, as some have been mentioned above.
The C4 fuel tank volume is "non linear" -- the top half of the tank has more volume than the bottom half.
And, the fuel tank gauge rheostat is "linear."
Therefore, they aren't a good match.
So, when the fuel gauge reads a linear half way, you have the volume of the smallest half left.
Here is how I view my fuel gauge reading:
When it starts to move down from full = half tank
half tank = 1/4 tank
1/8 tank = you better be at the gas station now
Tom Piper
The C4 fuel tank volume is "non linear" -- the top half of the tank has more volume than the bottom half.
And, the fuel tank gauge rheostat is "linear."
Therefore, they aren't a good match.
So, when the fuel gauge reads a linear half way, you have the volume of the smallest half left.
Here is how I view my fuel gauge reading:
When it starts to move down from full = half tank
half tank = 1/4 tank
1/8 tank = you better be at the gas station now
Tom Piper
Last edited by Tom Piper; May 22, 2006 at 06:36 AM.
