I have an 88 Formula that I put a 383 SB in and changed to a custom EFI system controlled by a Megasquirt ECM. The stock ECM is still connected and still controlling verything but the EFI. My question is, does the stock ECM have a fuel pump shut off triggered at high RPMs as a rev limiter. The EFI goes very lean at about 5000 rpm. I am running 29 pph injectors which should be plenty, I have even increased fuel pressure to 60 psi and the same thing happens, injectors are hitting 100% duty cycle, this makes me think fuel supply is being shut off.

Any input would be appreciated.

 

if your injectors are 100% Duty Cycle, that means they are constantly open. Also known as static.

You need higher fuel pressure(which you already tried), or bigger injectors. The bigger injectors will flow more fuel and hopefully stay within bout 80% of maximum duty cycle.

EDIT: Sorry, I missed that in the middle of the paragraph. Still, 100% Duty Cycle is still bad.

 

My question is, does the stock ECM have a fuel pump shut off triggered at high RPMs as a rev limiter.

No, it does not.

It may be that the fuel pump can not supply enough volume.

RBob.

 

That's also a possibility I was wondering about, this was a TBI car but I installed an inline MSD high pressure fuel pump, maybe the stock pump in the tank cannot supply enough fuel to the high pressure pump at max HP. This motor should only be in about the 450 HP range and even Edelbrock says the 29 pph injectors should be big enough.
Thanks for the input.