I have an 84 Z28. I'm doing a lot of work in this car including engine and rear end swap. When i bought this car it had a 305 with a carb and the mechanical fuel pump. When i pulled the rear end out i dropped the tank to have a look inside and found it also has an electric pump in the tank. Now according to the vin number this car was originally equipped with the L69 engine package which from what i understand is a carb motor with the mechanical fuel pump. How ever the fuel pump in this tank is actually wired for the pump. Why would this car have 2 fuel pumps and why would a carb car be wired for an electric fuel pump?

 

What's the 8th character of the VIN?

 

Helper pump in the tank to prevent vapor lock. Could be factory installed on l69 or later lg4, or as a dealer installed fix. Keep it.

 

Our 84 HO had both mechanical on block and electric in tank. When I researched it with O'Reilly, the low pressure electric in tank was only listed for the HO engine.

The pickup and in tank wiring looked factory. The pickup was broken and would not use all the fuel in the tank. We replaced tank with spectrum 88 and I think the pickup was the same. Since we would have to modify the pickup to accept the 84 electric pump, we did not replace it and are using the mechanical only.

 

Is there an easier way to find out if a car has the helper pump without removing the tank. I am having a problem with my 85 T/A where it seems to loose fuel pressure at high RPM's. I see that I have a fuel pump relay and a fuel pump fuse. I believe that if I have the helper pump that it has gone bad and is causing the problem by making the mechanical pump work harder to compensate.