Put a new fuel system on my Duster because I had it on the dyno and around 4900 rpm the fuel pressure went from 6.5 down to 2. The motor is a stroked 340 (418) with ported eddy heads. It had a Cater fuel pump (120gph) with a 3/8 pick up and a 3/8 fuel line. I upgraded to a 1/2 inch pick up and 1/2 inch fuel line. The pump is an Edelbrock (172gph) # 17003. It is supposed to have 8.5-9 psi and it requires q regulator. The car seems to run great but, it has 6-6.5 psi. There is no adjustment at the regulator because the lowest setting is 7 psi. This is the second pump on ths car in 2 weeks. The first pump had only 5 psi so this one is a little better. I know that 6.5 psi is good but accordind to Edelbrock it should be 8.5-9 psi. I have checked the system multiple times for leaks and there is none. I have not had it back to the dyno yet but I would like to get it as right as I can before I get there. Am I over looking somthing? Has anyone else used one of these pumps if so could you ever get 8.5 to 9 psi out of it? I am at my whits end with this project. Please help, all advice is appreciated. Thanks.

hi
your problem is you are using a mechanical pump .
it runs off the cam which turn at 1/2 engine speed !
real performance engines need a elictrical pump that has no consern of what engine speed is .

get a carter elect 4594 and install it at the tank for a pusher and eliminate the mechanical .

quiet / efficient !

6-8 psi full time !

You've probably already thought of this, but since you have had two of these pumps both produce low pressure, have you tried a different gauge, just to be sure? Don't use a liquid filled gauge in the engine compartment as they read lower the warmer they get.

If you've already verified that it's not the gauge, and Edelbrock says that the pressure should be closer to 9 psi, check the eccentric. The maximum pressure produced is dependent on several factors including how far the arm is moved by the eccentric. If the eccentric is worn....

We have customers running in the 10's with our 1100HP mechanical pumps. If all else fails, we can make an 1100HP pump for your 340 via special order (takes about 2-3 weeks as we don't stock the arm). Check the graphs on this page:

http://www.robbmcperformance.com/products/amc1100.html

Maybe I'm missing something but I'm not seeing a fuel delivery prob here. If you have ~3-4 psi at the carb @WOT under load at 4900 (or as high as you turn it) it's not starving.

I did use a high quality hand held fuel pressure gauge with a 5 foot hose to keep it away from the heat as well as the in line gauge. The liquid filled in line gauge did register a little lower pressure. I do realize that 6 - 6.5 psi is good as long as it maintains close to that at high speed but Edelbrock says it should have 8.5 - 9 psi. As far as the eccentric on the camshaft it is a newer motor with about 500 miles in it.