According to Holley fuel techs, the fuel pressure should be no more than 7 psi; 6 psi is ideal. Step 3: Use The Carburetor's Sight Plugs To Inspect The Fuel Level: With the engine off, remove the sight plugs from the fuel bowl to check the current fuel level.tep 5: Fuel Level Is Too High If fuel is pouring out of the sight plug then the fuel level is set too high, and the float must be lowered in the fuel bowl. a) Begin by lowering the fuel level in the fuel bowl to bring down the float.