The V8 Owners Forum -

Hi guys,

I have a fuel pressure boost valve fitted and on tick over (800 rpm) I've set the pressure at 36 psi but at 1100 rpm it drops to 34 psi, 2400 rpm 30 psi.

It seems that the pressure is dropping about 1 psi for every 300 rpms, so will this mean when I hit 5100 rpm i'll only have 21 psi? Or will the pressure level off to at a certain point?

I have a gut feeling something is not right.

The question i have is what pressure should i initially set the valve at?
Should the pressure be dropping of like this?
Should I fit a secondary pump?

Cheers Paul

I had one fitted to my car and my engine tuner advised me to remove it and fit the oe fuel reg which is what we did and have been running for a while

A basic reg refers to engine vacuum. The idea being to counteract the 'suck' on the injectors that vacuum causes. The higher the vacuum and suck, the lower the pressure. To give a (near) constant flow from the injector.

Rising rate regs attempt to increase fuel flow under certain conditions. This may improve a system that runs weak. But simply increasing the fuel pressure would do this too. They would be pointless with MegaSquirt as you can map that for the fulling you want at any load, etc. They can sort of help the early flapper injection which has a tendency to run weak.

Thanks guys for the feed back.

My system is the early flapper type, I'm aiming to convert to megasquirt in the next year or two once i've got this engine run in properly.