50 vs 40 psi? Does it matter

skipnrocks · Sep 13, 2015

I am running a tuned port 383. I used a gm fuel pump with filter regulated pressure. It's running about 50 psi. The manual for my fuel injection says I should be running 40. With this psi jump throw my tune way out of whack? Or should it be ok? It doesn't seem to run too Rich but I thought I would ask.

pholmann · Sep 13, 2015

Your fuel pressure regulator should knock it back. If it isn't, then yes it will affect things. Are you talking about 50 from the pump or 50 after the regulator?

skipnrocks · Sep 13, 2015

I am 50 psi at the rail. The instructions call for 40 at the rail. I have a corvette filter on so it maxes at 58 but running it stays about 50. I tried to find a filter like the vette one with the regulator without luck. All I could find is vacuum controlled units. I dont really want to tear the floors out the buggy and run a return line...

zukimaster · Sep 13, 2015

No return? Thought all fuel injection had to have a return, but I don't know that much either. :dunno:

lowbudgetjunk · Sep 13, 2015

zukimaster said:
No return? Thought all fuel injection had to have a return, but I don't know that much either.

I would have gone with that too. You get max pressure for when you need it, the rest diverts back to the tank when you don't. I do know my diesel does that, because I have bent and repaired the lines on the frame rail and in the tank.

skipnrocks · Sep 13, 2015

zukimaster said:
No return? Thought all fuel injection had to have a return, but I don't know that much either.

The return is through the fuel regulated filter.

skipnrocks · Sep 13, 2015

I wish I could just find a similar filter for 40 psi

d_daffron · Sep 13, 2015

If you're set on keeping the 50 psi regulator/filter setup and you don't have the ability to tune the computer you could change out the injectors to a smaller lb/hr injector. There are quite a few fuel injector flow rate caluclators on the internet that could help you out.
For example say your engine has an injector that flows 24lb/hr at 40psi it will flow 27 lb/hr at the 50psi youre running. To get back to the 24 lb/hr flow rate your engine was designed for you could change the 24 lb/hr at 40 psi injectors out for injectors that are rated for 20 lb/hr at 40 psi and run them at 50 psi which would give you 24 lb/hr flow your engine and ecm were designed for while running at the 50psi fuel pressure your regulator puts out.