Fuel level issue

bowez

bowez

2nd Gear Poster
Joined
Jul 19, 2024
Messages
91
Location
Nashville
Vehicle Details
93 SC
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My fuel gauge went from 1/2 to Full while driving Saturday. I know with how much I've drive it should be 1/4 to less, any input/ideas the most likely issue? Time to drop the tank?

After restarting I did watch the gauge go from 7/8 full to Full.
 
bowez said:
My fuel gauge went from 1/2 to Full while driving Saturday. I know with how much I've drive it should be 1/4 to less, any input/ideas the most likely issue? Time to drop the tank?

After restarting I did watch the gauge go from 7/8 full to Full.
Click to expand...
Float maybe getting stuck/ issues with fuel sending unit? Would be my first assumption but idk if these cars have a float or if its all electronic. Ive never even dropped a tank on one of these so take my opinion with a grain of salt.
 
I've never personally had to futz with it, but I'd start by reflowing the solder joints. IIRC when it goes bad it opens up and goes full ground, which is a full tank on the gauge.

I'm sure I'm wrong or missing something important though, so wait until Matt or Greg or someone who is sure chimes in. :)
 
I can try to scan the factory fuel gauge troubleshooting flowchart, but most of it requires manipulating the float. I had an '89 SC in the shop recently that always read full. I swapped in a different cluster (with anti-slosh module) and got the same thing. Wound up having to replace the sending unit in the tank.
 
Check the cluster as well. When I got mine forever ago the gauge was stuck on full. There is a chip on the right side of the cluster. If it slides out some and looses connection it will go to full. I slide it back in and never had an issue since. That was over 15 years ago.
 
AdamG said:
Check the cluster as well. When I got mine forever ago the gauge was stuck on full. There is a chip on the right side of the cluster. If it slides out some and looses connection it will go to full. I slide it back in and never had an issue since. That was over 15 years ago.
Click to expand...
Right. That is the anti-slosh module Terminator mentioned above. Hopefully that is it, because it is a lot easier than the fuel sending unit.
 
Hmm. I need to investigate. My gauge is all over the place. Generally hangs between 3/4 and full until it gets low then it "may" drop to 1/4 or less momentarily and shoot back to full. I did run it out 6 months ago so now I watch my trip odometer and track my fuel qty. I've got years of consistent mileage of 22-24 mpg on my daily commute. What annoys me is pre-paying and guessing how much it will hold and it clicking fill $6.00 left. Most times it goes back on card but have to go in to be sure.
 
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