95 4.3 stalls when braking, only when fuel level is low-below 1/2 tank. It stalls consistently on any grade and shows no codes, it doesn't hesitate or bog, just quickly dies, the lights stay on.. It starts right back up.
It has original single tank which was removed and cleaned out, the hoses have been checked along with the fuel pump, the sending unit may be off by a 1/4. I put 4 gallons in and drove for a while with no problems, had to spike the brakes and it stalled. After the fuel went lower it stalled more consistently when braking. Someone told me there is some type of a control box behind the dash that works with the sending unit and the fuel pump, theory is when gas is low and sloshing the sending unit shorts out the fuel pump. someone else said it may be something to do with the emergency fuel shut off.. I talked to a GM mechanic and he laughed at me...

 

If this is a Vortec 4.3 motor, you might try some carb cleaner in the throat of the upper plenum butterfly. Remove the aircleaner/air flow sensor, spray some cleaner on a rag and wipe that opening clean as far as you can reach. You'll have to open the butterfly to be able to clean beyond it.

 

Ever change your fuel filter?

 

The used car dealer we bought it from changed the fuel filter.
Do you think a dirty plenum would cause it to die when low on fuel ?

 

I am thinking it is tied into your vacuum system. Your brakes have a vacuum booster. The vaccum comes from the engine vacuum system. Check for any leaking hoses, any broken hoses, etc.

 

the fuel pump could have a hole or a gap somewhere in the line, allowing the low fuel level to starve out the fuel pump.. my 94 runs out of gas just below the 1/4 tank line... i think it is because the fuel pump sits higher in the tank than it should