car idles great when the ac is on, not when off

DonaldHays · Sep 29th, 2005, 07:10 PM

Hey everyone,

I am still trying to track down the small weird from time to time idle issues I have with my 94 VG30 she now has almost 85k on her and its weird as it comes and goes at times and don’t always do this

Seems to do it more once I hit or get below half a tank of fuel, if the car is idling weird (bouncing within the 200-300 that she does I flip on the ac and she is fine then!) If you flip the ac back off she goes back to hunting and flip the ac back on and the idle is fine again (since the ac seems to cure the issue I want to rule out the fuel pump maybe going bad)

Wouldn’t flipping the ac on make the car demand more fuel and maybe fix low pressure and make it seem as if its not the fuel pump doing this. I also don’t hear the fuel pump whine or crying as I have seen others do before they go dead. Any tips? Of course the plugs/fuel filter/air filter/cap and rotor are all fine and replaced not very long ago

Thanks,

Donnie H.

nismosleeper · Sep 30th, 2005, 12:33 AM

The first thing that I do when i get a car with a bad idle, is change the plugs, and replace any old vacuum lines...cheap and effective. Your ac thing does soung fuel related though. Could be that you fuel pump is getting hot (gas acts as a coolant, so when it's low=no coolant) and not performing for you. You would probably have to use a multimeter to check that though.