Poor fuel delivery - drivers side tank, 87 350 tbi

[Dave87]

Yesterday when the passenger side gas tank was almost but not totally empty, I switched to the driver's side tank.  At first, everything was ok but in a few minutes the car became sluggish and would either surge or stall at idle. If I vigorously pump the pedal I could keep it running. I switched back to the passenger tank and immediately all was ok again.

I first thought it might be a bad fuel filter on that tank but I find only one filter inside the frame rail on the passenger side. I thought that each tank would have a separate filter but I cant find one on the drivers side.

So, if there's only one filter for the 2 tanks then it can't be the filter or it would not matter what side tank is in use. Right?  Anyway, could it be the drivers side fuel pump?  I figured that if I could keep the car running at idle by pumping the gas, the fuel pump should be working.  I hate to drop the driver side tank unless necessary.

What do you guys think?

[zieg85]

The fuel pump in the tank is bad with symptoms you describe.  If you have access to a fuel pressure gauge that would confirm it.

[Irish_Alley]

ran into a problem on a 90s chevy there is a rubber line between the fuel pump and fuel pump assembly this line will crack and cause a poor running condition almost like a miss fire and first reaction would be to do a tune up but since you have dual tanks you eliminated that. a new pump will come with the line or if you take yours out and you might see the hose in bad shape. might save you some bucks but get the pump also just incase