Fuel Pressure - Fuelly Forums

Android Users - Coming Soon! - Migrating from aCar 4.8 to 5.0

Reply
 
Thread Tools Display Modes
 
Old 08-12-2008, 05:33 PM   #1
Registered Member
 
Join Date: Aug 2008
Posts: 4
Fuel Pressure

How much full pressure is needed to open an injector that is designed to operate about 38 lbs? When I was talking to Bob last night and he was explaining to me that you needed to lean the engine. He was showing me this display on his dash and plugged into the computer port. The reason I am asking is because if it only takes 20 PSI to open the injector then you could install an in line fuel pressure regulator and unplug the vacuum line so the factory regulator will be wide open. He was explaining about trying to change the computers program but I told him why don't you slow down the gas. That is the one thing that is still mechanical to a point.
Have you tried this?
Dave
__________________

exhaustartist@gmail.com is offline   Reply With Quote
Old 08-12-2008, 06:55 PM   #2
Senior Member
 
Join Date: Mar 2011
Posts: 446
Country: United States
Location: Charlotte nc
fuel injectors are opened electrically the fuel pressure is used to create a proper spray that atomizes the fuel with the air correctly. reducing the fuel pressure will result in a poor mix of gas and air miss fires and possibly burned pistons (worst case) due to puddling. What would be the best method of reducing the amount of fuel injected is to reduce the time the injector is open. there are several ways to do this but the easiest is press the gas pedal less hard a second way is to make the computer think it's ingesting hot air either by tricking the IAT or actually ingesting hot air. lowering fuel pressure will only make the spray pattern look more like a sputter than a spray.
__________________

Philip1 is offline   Reply With Quote
Old 08-13-2008, 05:39 AM   #3
Registered Member
 
Join Date: Jun 2008
Posts: 6
Country: United States
Working in this direction, it would be better to RAISE the fuel pressure, for the atomization that Philip1 is referring to. However, you would need to be able to adjust the computer code to reduce the pulse length (length of time the injector is open, squirting fuel) and you would need an adjustable fuel pressure regulator to raise the fuel pressure.
The combination of these 2 for a higher pressure injection would yield roughly the same amount of fuel injected, but better atomized, which would yield a more efficient and complete combustion burn, which leads to less throttle needed to move the vehicle, and better MPG.
Backtobasics is offline   Reply With Quote
Old 08-13-2008, 05:50 AM   #4
Registered Member
 
Join Date: Aug 2008
Posts: 4
Phil,
I understand why you can't just reduce the fuel pressure. What I was referring to making the engine leaner for the H2 that you are making can take over and run the engine.
exhaustartist@gmail.com is offline   Reply With Quote
Old 08-13-2008, 08:40 AM   #5
Registered Member
 
kamesama980's Avatar
 
Join Date: Nov 2007
Posts: 742
Country: United States
Location: Columbus, IN, USA
Send a message via AIM to kamesama980 Send a message via Yahoo to kamesama980
depends on the engine. but in a FI situation, it won't help you because the o2 sensor will read that you're running lean and it'll lengthen the injector pulse to accomodate lower pressure. if your car is new enough, it may even have a pressure sensor on the rail to tell the ECU what the pressure is... again causing the ECU to try to correct it.

If you want to lean out the engine, just do it like everyone else... EFIE, O2 spacer, or something like that
__________________
-Russell
1991 Toyota Pickup 22R-E 2.4 I4/5 speed
1990 Toyota Cressida 7M-GE 3.0 I6/5-speed manual
mechanic, carpenter, stagehand, rigger, and know-it-all smartass
"You don't get to judge me for how I fix what you break"
kamesama980 is offline   Reply With Quote
Old 08-13-2008, 12:59 PM   #6
Registered Member
 
Join Date: Oct 2006
Posts: 557
Country: United States
38 psi?


Sorry about the rolling eyes, but I'm more accustomed to 3800 psi fuel pressure in my mid-90's era diesel than 38 psi.
Higher pressures provide finer, more uniform, near to atomization of the fuel droplets for more complete combustion, lower emissions and more power.
And now my new-to-me 2005 diesel has injectors that operate at up to 30,000 psi. Time to bone up on that system.
Lug_Nut is offline   Reply With Quote
Old 08-13-2008, 05:30 PM   #7
Senior Member
 
Join Date: Mar 2011
Posts: 446
Country: United States
Location: Charlotte nc
with gasoline the injectors are designed to run at a specific pressure. You can raise the pressure and the injector will act like a larger injector. Go too far and the pressure will lock the injector either open or closed depending on make and design. I would go with Kamesama's suggestions.
__________________

Philip1 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Incorrect Milage Calcuatlion PatM Fuelly Web Support and Community News 4 07-17-2009 08:21 PM
Missing Fuelup jmonty Fuelly Web Support and Community News 3 05-27-2009 05:10 AM
total fuel cost for fill-up instead of price per gallon EmptyH Fuelly Web Support and Community News 1 08-26-2008 12:14 PM
Why did it take me so long to find this place? Baranfin Introduce Yourself - New member Welcome 6 05-31-2008 05:17 PM
hi new member here and ive got some sick ideas! csrmel Introduce Yourself - New member Welcome 6 10-18-2007 02:23 PM

Powered by vBadvanced CMPS v3.2.3


All times are GMT -8. The time now is 09:07 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.