Fuel Pressure - ZR-1 Net Registry Forums

LGAFF · 09-13-2013

Idle with FPR connected 50lbs
Idle with FPR disconnected....60lbs

Free Rev with FPR connected drops to 40lbs

Free Rev with FPR disconencted 60lbs

Does the lack of load account for the drop?

XfireZ51 · 09-13-2013

The idea of an FPR in PFI is to maintain the same fuel
flow across all MAP levels.

LGAFF · 09-13-2013

So faulty FPR? I would think if it were the pump, it would drop when the FPR was disconnected, same for the filter being clogged...

scottfab · 09-13-2013

Quote:

Originally Posted by LGAFF

Idle with FPR connected 50lbs
Idle with FPR disconnected....60lbs

These numbers look great to me.
From memory mine were 49 and 55

Quote:

Originally Posted by LGAFF

Free Rev with FPR connected drops to 40lbs

Free Rev with FPR disconencted 60lbs

Does the lack of load account for the drop?

Really ? 40?
Mine hits 44 but sometimes 43.

Marc Haibeck · 09-14-2013

Hi Lee,

Yes, faulty fuel pressure regulator.

On an LT5 the fuel pressure should be 3 Bar or 43 psi at idle with the manifold vacuum on the regulator.

With the vacuum hose off or at WOT the fuel pressure should be 51 PSI +/- 1 psi.

In the range of 45 to 55 psi each psi of pressure changes the AFR about .1. At 60 PSI at WOT you could be running an AFR point rich.

Schrade · 09-14-2013

Ray Bohacz says that port fuel injection has capability of 'Acceleration Enrichment', and 'DE-celeration enLEANment' (the dashpot, in the carb), and how to check it, as Marc is saying here (5th page, 1st column, in PURPLE) :

(and when you know it all, like most gurus here, sometimes the simple stuff gets right by you)

(every time I read this article, something in it comes to me, that I didn't get before)

(and never mind my notes, just ideas I had as I read and re-read)

Schrade · 09-14-2013

(5th page, 1st column, in PURPLE)

Schrade · 09-14-2013

and the last 2 pages

XfireZ51 · 09-14-2013

AE is a pumpshot in carb terms. DE is not to be confused w DFCO
cuts off fuel not reduces it.

XfireZ51 · 09-14-2013

At 51psi, 22.7# injectors will flow as 24.7#, at 60psi, they flow like 27#. So at least 10% richer all around. Your going from a hypothetical 12.8 to an 11.6AFR at WOT.

09-13-2013	#1
LGAFF Join Date: Mar 2007 Location: Crystal Lake, IL Posts: 7,194	Fuel Pressure Idle with FPR connected 50lbs Idle with FPR disconnected....60lbs Free Rev with FPR connected drops to 40lbs Free Rev with FPR disconencted 60lbs Does the lack of load account for the drop? __________________ LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359

09-13-2013	#2
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,698	Re: Fuel Pressure The idea of an FPR in PFI is to maintain the same fuel flow across all MAP levels. __________________ [SIGPIC][/SIGPIC]Former Membership Chairman Former ZR-1 Registry - BOD 1972 Corvette 4speed base Coupe SOLD long time ago 1984 Corvette Z-51/4+3 SOLD 1992 Corvette ZR-1 Aqua/Gray #474 SOLD 1992 Corvette ZR-1 Black Rose/Cognac #458 2014 Honda VFR Interceptor DX

09-13-2013	#3
LGAFF Join Date: Mar 2007 Location: Crystal Lake, IL Posts: 7,194	Re: Fuel Pressure So faulty FPR? I would think if it were the pump, it would drop when the FPR was disconnected, same for the filter being clogged... __________________ LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359

09-14-2013	#5
Marc Haibeck Join Date: May 2007 Location: Addison IL Posts: 241	Re: Fuel Pressure Hi Lee, Yes, faulty fuel pressure regulator. On an LT5 the fuel pressure should be 3 Bar or 43 psi at idle with the manifold vacuum on the regulator. With the vacuum hose off or at WOT the fuel pressure should be 51 PSI +/- 1 psi. In the range of 45 to 55 psi each psi of pressure changes the AFR about .1. At 60 PSI at WOT you could be running an AFR point rich.

09-14-2013	#6
Schrade Join Date: Dec 2012 Location: NC Posts: 1,786	Re: Fuel Pressure Ray Bohacz says that port fuel injection has capability of 'Acceleration Enrichment', and 'DE-celeration enLEANment' (the dashpot, in the carb), and how to check it, as Marc is saying here (5th page, 1st column, in PURPLE) : (and when you know it all, like most gurus here, sometimes the simple stuff gets right by you) (every time I read this article, something in it comes to me, that I didn't get before) (and never mind my notes, just ideas I had as I read and re-read) __________________ I'm getting my snappics / threads removed blindly as fast as I can, to get in compliance with copyright / license TOS on the boards here (lots of FSM pages and other copyright / license violations on my part; sorry guys). And thanks to all the guys who didn't whine when I posted those FSM copyrighted / licensed stuff in my threads... ( :thumbsup: [b]and to think I complied with a mod's request to delete a pic of him in a Challenge Car in NCM Museum, so he wouldn't get in hot water)[/b] Thanks to several guys here for sending parts FREE; BearlyFlying, WeGone, Geezer, GoldCylon, and more there, TonyD, mike100, fletchusmc... 1990 #2794; 4L60e Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless, Power Effects 3" [IMG]https://lh5.googleusercontent.com/-GHpfzty7DVU/UQn-0Ru2xAI/AAAAAAAAA14/08mz1p4QLD4/s445/Screenshot-5.png[/IMG]

09-14-2013	#8
Schrade Join Date: Dec 2012 Location: NC Posts: 1,786	Re: Fuel Pressure and the last 2 pages __________________ I'm getting my snappics / threads removed blindly as fast as I can, to get in compliance with copyright / license TOS on the boards here (lots of FSM pages and other copyright / license violations on my part; sorry guys). And thanks to all the guys who didn't whine when I posted those FSM copyrighted / licensed stuff in my threads... ( :thumbsup: [b]and to think I complied with a mod's request to delete a pic of him in a Challenge Car in NCM Museum, so he wouldn't get in hot water)[/b] Thanks to several guys here for sending parts FREE; BearlyFlying, WeGone, Geezer, GoldCylon, and more there, TonyD, mike100, fletchusmc... 1990 #2794; 4L60e Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless, Power Effects 3" [IMG]https://lh5.googleusercontent.com/-GHpfzty7DVU/UQn-0Ru2xAI/AAAAAAAAA14/08mz1p4QLD4/s445/Screenshot-5.png[/IMG]

09-14-2013	#9
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,698	Re: Fuel Pressure AE is a pumpshot in carb terms. DE is not to be confused w DFCO cuts off fuel not reduces it. __________________ [SIGPIC][/SIGPIC]Former Membership Chairman Former ZR-1 Registry - BOD 1972 Corvette 4speed base Coupe SOLD long time ago 1984 Corvette Z-51/4+3 SOLD 1992 Corvette ZR-1 Aqua/Gray #474 SOLD 1992 Corvette ZR-1 Black Rose/Cognac #458 2014 Honda VFR Interceptor DX

09-14-2013	#10
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,698	Re: Fuel Pressure At 51psi, 22.7# injectors will flow as 24.7#, at 60psi, they flow like 27#. So at least 10% richer all around. Your going from a hypothetical 12.8 to an 11.6AFR at WOT. __________________ [SIGPIC][/SIGPIC]Former Membership Chairman Former ZR-1 Registry - BOD 1972 Corvette 4speed base Coupe SOLD long time ago 1984 Corvette Z-51/4+3 SOLD 1992 Corvette ZR-1 Aqua/Gray #474 SOLD 1992 Corvette ZR-1 Black Rose/Cognac #458 2014 Honda VFR Interceptor DX