Fuel pressure for 5.0

From: Doug Schulz <>
Date: Wed, 6 Feb 2002 17:23:44 -0700

I have just completed my installation of my 5.0 and have been having
problems with a rich, rough idle that sometimes surges. Power hasn't been
what is should be, either. It's a 320 HP 5.0 with E303 cam, 9.5:1
compression, GT40P heads, 24 lb injectors, Cobra intake, 77mm MAF, 65mm(?,
forget) TB and Explorer serp setup.
I have been running the E2000 pumps and it runs OK, but with the
aforementioned problems. Today, I took it to All Mustang, and they said it
isn't getting enough fuel volume. Said a motor like mine needs more juice
than the E2000 can deliver and recommended installing a Holley NOS stage 2
pump in line after the E2000. Although I can adjust the fuel pressure up
(Aeromotive regulator) it drops when the throttle is WOT. I thought that was
normal, since the injectors are pulling more, but he says the pressure
should be about 42 psi at WOT always. He said to adjust the regulator to 42
with the vacuum hose off and then it should drop 8-10 psi when the vacuum is
hooked back up. Then when I rev WOT, it should go up to 42 and stay within a
lb or two. Now, before the new pump, I am at 45psi vacuum off, just to get
any power at WOT and it makes the idle rich. Probably a simple problem for
those in the know, but I'm a novice at this EFI stuff. Bottom line is,
whatever you run, it better give 42 psi at WOT or you'll have problems. He
also said to run TPS at .98 always and 36 degrees of advance, spout out,
then leave the spout out. Evidently the EFI timing chases the E303's lopey
idle too much, and the high initial advance gives a bit more bottom end,
too. Remember that these settings are for an engine like mine and might not
apply to a stock one. We'll see whan I put in the pump tomorrow.

Doug Schulz
Received on Sat Feb 09 2002 - 17:22:56 MST

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