Low Fuel Pressure

[Cliff K.]

I have a 1964 327/365hp that we can only get about 2.5 lbs of fuel pressure. We just replaced the camshaft because the original GM shaft lobes finally wore off (not the fuel lobe).
Replaced the fuel pump with a new nos correct pump. So far, we have put 3 diferent fuel pumps on, all read the same.
We have used 3 different gauges, all read the same.
We provided an alternate fuel source (other that the tank) to eleminate the sender unit screen/sock, no change in reading.
We checked the fuel pump lobe on the new camshaft and it checked the same as another sbc shaft ( I think it was about .350)
We compared the fuel pump push rod with a new one and found no discernable difference.

Now we are stumped and need help. Anyone with any ideas?

[William C.]

Re: Low Fuel Pressure

What pump are you using? Should be a 40083 pump.

[Clem Z.]

Re: Low Fuel Pressure

I have a 1964 327/365hp that we can only get about 2.5 lbs of fuel pressure. We just replaced the camshaft because the original GM shaft lobes finally wore off (not the fuel lobe).
Replaced the fuel pump with a new nos correct pump. So far, we have put 3 diferent fuel pumps on, all read the same.
We have used 3 different gauges, all read the same.
We provided an alternate fuel source (other that the tank) to eleminate the sender unit screen/sock, no change in reading.
We checked the fuel pump lobe on the new camshaft and it checked the same as another sbc shaft ( I think it was about .350)
We compared the fuel pump push rod with a new one and found no discernable difference.

Now we are stumped and need help. Anyone with any ideas?

make sure you are getting full travel in the new fuel pump push rod. i would try the old push rod because if for some reason the new one is not being pushed back up all the way with the pump arm you will not get full pressure. you can check this by removing the pump and push the rod upward with you finger while some spins the engine on the starter

[Cliff K.]

Re: Low Fuel Pressure

The nos fuel pump is an 083, we also used a rebuilt/replacement pump and the replacement pump that was previously on the engine. The push rod is the rod that was on the engine, we did not replace the push rod.