Runs rough when low on gas
Thread Starter
Drifting
Joined: Apr 2002
Posts: 2,075
Likes: 34
From: Hendersonville Tennessee
Runs rough when low on gas
Sorry if this has been discussed before. I tried search for info, but the search function seems to be useless, returns everything unrelated to what I'm searching for.
Anyway, on my 88 S4, when the gas tank is near empty, the car runs very rough at idle and when going from a stop, almost like it's in limp mode. Smoothes out after the rpm's get up and goes away when the tank is filled. Never does it when there is a decent amount of fuel in the tank.
What does this indicate, tank pump, sediment in the bottom of the tank, something electronic? I replaced the filter outside the tank and the check valve about a year ago. I do notice that the fuel pump buzzes quite loudly when the tank is low as well.
Anyway, on my 88 S4, when the gas tank is near empty, the car runs very rough at idle and when going from a stop, almost like it's in limp mode. Smoothes out after the rpm's get up and goes away when the tank is filled. Never does it when there is a decent amount of fuel in the tank.
What does this indicate, tank pump, sediment in the bottom of the tank, something electronic? I replaced the filter outside the tank and the check valve about a year ago. I do notice that the fuel pump buzzes quite loudly when the tank is low as well.
Three Wheelin'
Joined: Jun 2008
Posts: 1,914
Likes: 0
From: Surprise, Arizona
Probably sediment... My 79' had this problem when I first got it. It would even stall out completely when low on gas and turning left... The tank had been repaired previously, so I replaced it with a good used tank. Problem went away. I never looked into it, but maybe the repair material caused the problem....
Rennlist Member
Joined: Jan 2004
Posts: 12,620
Likes: 8
From: Boulder Creek, CA
When it's low, running poorly with the fuel pump buzzing loudly, while the car is running remove the gas cap. If you hear the sound of air rushing in, then the problem is with the vent in the gas cap -- it's plugged, allowing a vacuum to build up in the tank.
Sediment would always be on the bottom, regardless of fuel level, I'd think. When the fuel level is low, you can easily remove the fuel level sender and look into the tank with a flashlight to see if there is any crud on the bottom.
Sediment would always be on the bottom, regardless of fuel level, I'd think. When the fuel level is low, you can easily remove the fuel level sender and look into the tank with a flashlight to see if there is any crud on the bottom.
