Fuel Pressure dropping while under boost
Thread Starter
Advanced
Joined: Oct 2016
Posts: 72
Likes: 2
From: Calgary Alberta
Fuel Pressure dropping while under boost
My 97 running 7065 single top mount is dropping fuel pressure when under boost of 12lbs. Before the dyno we upgrade the fuel pump to a Aeromotive stealth 340 pump and put a new GM fuel filter in. Now we are trying to figure out why its dropping fuel pressure when under boost at 12lbs.. Any help would be great.
Melting Slicks
Joined: Jul 2004
Posts: 2,844
Likes: 144
From: Northern Ireland
Actual pressure across the injector will change, but that isnt what is being measured.
Causes can be many. Not enough pump, wiring, lines, regulator, filter etc etc
Burning Brakes
Joined: Oct 2005
Posts: 1,089
Likes: 82
From: Kauhava, Finland
Melting Slicks
Joined: Jul 2004
Posts: 2,844
Likes: 144
From: Northern Ireland
Although a small drop wouldnt be a big deal...a large drop and as fast as that, far from ideal.
That said, the reading is 85psi dropping to 70psi ?
Firstly why is it at 85psi to start with ? Even if these are absolute figures as the units suggest...which would be around 70psi gauge dropping to 55psi....why is it starting high ?
A lot more info is needed here.
That said, the reading is 85psi dropping to 70psi ?
Firstly why is it at 85psi to start with ? Even if these are absolute figures as the units suggest...which would be around 70psi gauge dropping to 55psi....why is it starting high ?
A lot more info is needed here.
Supporting Vendor
Joined: Apr 2012
Posts: 2,671
Likes: 369
From: Forney TX
Not enough pump for the given circumstances. It's that simple. As mentioned earlier, it could be from a weak pump, defects in wiring or anything causing low voltage to the pump, or that your demand exceeds the limits of the pump, even when it's working properly.
Fuel volume capability of a pump is based largely on its output pressure and you're running far too much pressure on that pump regardless of any other circumstances.
Fuel volume capability of a pump is based largely on its output pressure and you're running far too much pressure on that pump regardless of any other circumstances.
__________________
Offering products from A&A Superchargers, East Coast Superchargers, Mechman Alternators, Mantic clutches, RPS clutches, Kooks Headers, Lakewood, LG, Brian Tooley Racing, Comp Cams, FAST, ARP, UPP Turbo systems, Wiseco, Callies, K1, MAST Motorsports, Haltech and many more. PM me for details.
Offering products from A&A Superchargers, East Coast Superchargers, Mechman Alternators, Mantic clutches, RPS clutches, Kooks Headers, Lakewood, LG, Brian Tooley Racing, Comp Cams, FAST, ARP, UPP Turbo systems, Wiseco, Callies, K1, MAST Motorsports, Haltech and many more. PM me for details.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Melting Slicks
Joined: Dec 2002
Posts: 2,480
Likes: 62
From: Middletown DE
Maybe a silly question, but are you running a Hotwire kit?
Your base pressure just seems really high. Pump maybe cannot keep up at that pressure. Might want to lower that. They have an adjustable regulator for the stock 97/8 rail.
Your base pressure just seems really high. Pump maybe cannot keep up at that pressure. Might want to lower that. They have an adjustable regulator for the stock 97/8 rail.
Thread Starter
Advanced
Joined: Oct 2016
Posts: 72
Likes: 2
From: Calgary Alberta
Would go throw some fuel in to cool down the pump and was fine again for a few pulls then would heat up and fuel pressure would drop. Swap the pump out for Walbro 450 and can do 10+ pulls and never drop fuel pressure or go lean.
Melting Slicks
Joined: Feb 2006
Posts: 3,191
Likes: 43
From: Scottsdale Az
I'm with everyone else, base pressure seems way to high.
Melting Slicks
Joined: Mar 2005
Posts: 2,225
Likes: 42
From: Okinawa
Yea because of 85psi fuel pressure. The higher the pressure you demand on a fuel pump the less it flows. If your pressure was 58 you would have been fine.
Last edited by SBCGENII; May 18, 2017 at 07:53 AM.