Electrical power causes car to go lean

[JOLTY TacoMan]

Anytime I use anything that draws electricity my car goes quite lean. No change on WOT but in idle or cruise its very noticeable. I can still use my headlights but turning the radio on or using the heat/ac fans lean it out. Any clue what it could be or how I could trace it down?

 

[VtecvrsTurbo]

Could be a weak alternator or a poor ground. Have you alternator tested, most shops do it free. You could also check the battery while the cars running and see voltage. I think around 14-14.5 is normal. Also if your not running a rewired fuel pump, id get that done

 

[DogWhistle]

^ +1 on the alternator check and fuel pump pressure test. Without engine mods, you shouldn't need a rewire on the fuel pump, so maybe your pump is starting to go.