Walbro fuel pump install
From GM Wiki
82-91 J bodies
Pictured to the right is a stock 82-92 Fuel pump, and a Walbro pump mounted into the fuel module. The mounted walbro pump fit directly into the stock fuel module, just as a stock unit would.
92 J bodies
J bodies from this year had a hybrid fuel module design. The pump itself was the same style as previous 82-91 years. However, instead of using a baffled tank, GM installed what is called a "fuel bucket" in a non-baffled tank. The fuel bucket acts as a small reservoir so when the fuel sloshes around during driving the fuel pump isn't starved for fuel. This requires that the bucket be filled by the pump when there is fuel available. 1992 fuel modules use a venturi powered from the pump's main pressure line to fill the bucket. 1993 and later modules use a separate output on the pump housing to drive the venturi.
93+ J bodies
The stock pump has 2 outlets. (Walbro pump shown to the right) The tiny one supplies pressure to a venturi system that sucks fuel into the bucket, keeping the bucket full at all times. The other outlet supplies fuel to the motor.
When installing a walbro pump made for 82-92 J-bodies into a 93+ J-body fuel module the choices are:
- Buy a walbro pump, drill a small hole in the top of the pump housing, attach (thread or glue) in a nipple for the small venturi fuel line and go.
- Buy a pump already modified by http://www.racetronix.com
- Swap to a earlier tank, with the standard fuel pump "Stick" and baffles. You will have to redo the lines on the chassis to fit with the older tank. You will also loose 2 gallons of fuel capacity and I'm not sure, but the older tanks have a slightly different shape to clear the exhaust.
- Use a standard walbro pump, cut open the bottom of the fuel bucket, and never let the car get below 1/3 to 1/2 a tank of gas.
- You could use the fuel pump from say a higher stock HP GM car, like a Vette or Camaro. I'm not sure the difference in flow, though.
