Electrical probably security problem on 2004 Chevrolet Blazer

I noticed when I turn off my engine the fuel gauge turns off like it is suppose to. When I got out of car i watched the gauges and after 30 to 45 sec the power to the gauge came on but with not as much fuel as when the engine is on

Asked by for the 2004 Chevrolet Blazer
Real sorry answered wrong question but will try to help you.