I'm having a problem with my gas gauge, for the last few days it has been going on and off. The problem started a few days ago when I let my friend borrow my car and he put $10 worth of regular in it and I usually use 89. When he gave me the car back the gauge wasnt workin. The next day I put $20 worth of 89 in the car and the gauge orked for a day. And now 3 days later the gauge doesnt work at all. So I hope somebody has encountered this problem and can help me fix it. Oh and for the record its an 88 GTU.

 

it's probably a bad sender. FWIW, 87 octane is the recommended fuel for N/A and stock TII. 91 is recommended for modified turbos.