GMC Repair: Stalling, electric fuel pump, gmc jimmy

Question
OK: 1997 GMC Jimmy 4.3 ltr. When the fuel gauge gets down to about an 1/8th of a tank the engine will keep stalling when you let off the gas. It starts right back up OK. (I know) keep more than an 1/8th of a tank of gas. Could it be that the fuel tank suction tube is not going to the bottom of the tank ? Thanks, Fred

Answer
OK, The most common faults are:

1. The micro screen attached to the bottom of the electric fuel pump in the fuel tank may be plugged up with foreign debris from the gas stations fuel tank and you pumped some of it into your fuel tank. There is a BY-PASS port located on the side of the pump for just this reason. However, When the fuel tank gage reads about 1/4 to 1/8th of remaining fuel in the tank, This BY-PASS port is now ABOVE the height of the gas in the tank thus causing it to stall due to lack of fuel.

2. Foreign debris can also buildup and plug the fuel pumps micro screen and the longer the pump runs the more debris is collected on the screen due to the suction from the fuel pump. Once the engine stalls the fuel pump stops and the debris falls away from the micro screen and is deposited back into the fuel tank. Now you restart the vehicle and the pump begins to suck the debris back onto the micro screen and the process keps repeating itself.

3. The small rubber hose that connects the fuel pump to the pickup tube is also exposed around 1/4 to 1/8th of remaining fuel in the tank and you start to suck air of which stalls out the engine.

4. Since the electric fuel pump in the fuel tank is cooled  
by the gasoline and as the remaining gas within the tank begins to get less and less, This exposes the pump above the level of the pump thus causing the pump to over heat and shut down for a minute or two.

5. The electrical connections at the fuel pump has been known to corrode and start to effect the fuel pump operation and it can get worse once these wires become exposed as when the tank is low on fuel.

These are the most common faults of this type of problem.

I would suggest that you drain out the fuel tank, Remove it from the vehicle, remove the fuel pump from the fuel tank and physically check for the above said possibilities. If your vehicle has in excess of 80,000 miles on it, I recommend that you replace the fuel pump as GM pumps are known to start to fail around this mileage.


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