Fuel pressure and injector questions
Fuel pressure and injector questions I have a 98 Z28 with the following mods:
Yank PT4000, TR224/114 cam, MAC headers, LS6 Intake, FTRA, most all of the bolt-ons and 3.23 gears. My average RPM through the ¼ mile is about 6000.
I noticed that on cool days at the track the car would sputter just before shifts (6400rpm) like I was running out of fuel. I AutoTaped the runs and the Injector Pulse Width showed that the injectors were operating at 94% - 98% capacity. I am running the stock 28lb injectors and fuel pump. I thought this to be a little strange because I was under the impression that 28lb injectors would support more HP than I could be making with my mods. As an indication of horse power my race weight is a little over 3500lbs and I usually trap around 116.4mph.
I checked my fuel pressure at the rail and it holds steady at 54psi at idle and when I rev it up.
Is my fuel pressure too low?
Could this be the reason that I am running out of fuel or are the injectors just too small?
Any comments and suggestions are welcomed.
Thanks
John
Yank PT4000, TR224/114 cam, MAC headers, LS6 Intake, FTRA, most all of the bolt-ons and 3.23 gears. My average RPM through the ¼ mile is about 6000.
I noticed that on cool days at the track the car would sputter just before shifts (6400rpm) like I was running out of fuel. I AutoTaped the runs and the Injector Pulse Width showed that the injectors were operating at 94% - 98% capacity. I am running the stock 28lb injectors and fuel pump. I thought this to be a little strange because I was under the impression that 28lb injectors would support more HP than I could be making with my mods. As an indication of horse power my race weight is a little over 3500lbs and I usually trap around 116.4mph.
I checked my fuel pressure at the rail and it holds steady at 54psi at idle and when I rev it up.
Is my fuel pressure too low?
Could this be the reason that I am running out of fuel or are the injectors just too small?
Any comments and suggestions are welcomed.
Thanks
John
Re: Fuel pressure and injector questions make sure the fp under load (not just free revving) stays up there.. but a pump would definitely not hurt anything.. or fix the regulator, that may be the problem too.. but i agree the injectors should be good at that level, they are just having to make up for the low fp.
Re: Fuel pressure and injector questions Thanks for the response.
How do you check the fuel pressure under load?
How do you determine whether the pressure problem is the pump or the regulator?
Thanks
John
<small>[ February 23, 2003, 05:06 PM: Message edited by: JNorris ]</small>
How do you check the fuel pressure under load?
How do you determine whether the pressure problem is the pump or the regulator?
Thanks
John
<small>[ February 23, 2003, 05:06 PM: Message edited by: JNorris ]</small>
Re: Fuel pressure and injector questions you need an in car fuel pressure regulator or check it while on a dyno..
also verify that you are getting at least 12 volts to the stock pump.. i would just get in there and replace both.. the regulator because you are only seeing 54 and the pump because well its just a really good idea.
also verify that you are getting at least 12 volts to the stock pump.. i would just get in there and replace both.. the regulator because you are only seeing 54 and the pump because well its just a really good idea.
Re: Fuel pressure and injector questions Do you recommend going back with the stock setup or aftermarket.
At some point I will add heads and a small wet shot (100hp)
What do you think about the Racetronix drop-in pump?
Racetronix link
Thanks
John
<small>[ February 25, 2003, 06:48 AM: Message edited by: JNorris ]</small>
At some point I will add heads and a small wet shot (100hp)
What do you think about the Racetronix drop-in pump?
Racetronix link
Thanks
John
<small>[ February 25, 2003, 06:48 AM: Message edited by: JNorris ]</small>
Re: Fuel pressure and injector questions i would reccomend a better pressure regulator than stock and the walbro pump for sure and see where that gets you.
the racetronix kit works well for 98's, but its really easy to get the same thing doing it yourself and save about a hundred bux if its worth that to you.
the racetronix kit works well for 98's, but its really easy to get the same thing doing it yourself and save about a hundred bux if its worth that to you.
Re: Fuel pressure and injector questions </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by MIGHTYMOUSE:
<strong> i would reccomend a better pressure regulator than stock and the walbro pump for sure and see where that gets you.
the racetronix kit works well for 98's, but its really easy to get the same thing doing it yourself and save about a hundred bux if its worth that to you. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">What aftermarket pressure regulator do you recommend and where do you get it?
I am always looking for a way to save $100. So I can get an aftermarket pressure regulator and a walbro 340 pump and replace the existing components.
Are there any online instructions or guides to follow?
Thanks
John
<strong> i would reccomend a better pressure regulator than stock and the walbro pump for sure and see where that gets you.
the racetronix kit works well for 98's, but its really easy to get the same thing doing it yourself and save about a hundred bux if its worth that to you. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">What aftermarket pressure regulator do you recommend and where do you get it?
I am always looking for a way to save $100. So I can get an aftermarket pressure regulator and a walbro 340 pump and replace the existing components.
Are there any online instructions or guides to follow?
Thanks
John
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Re: Fuel pressure and injector questions on a 98, the pump swap is pretty obvious and staight forward once you get into the tank and have a look around. i have pics on my website under fuel system just put one pump in there instead of two.
i have a charged air pump from ls1speed.com
it seems to be a favorite around here, at least for the forced induction crowd
i have a charged air pump from ls1speed.com
it seems to be a favorite around here, at least for the forced induction crowd
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Re: Fuel pressure and injector questions Stock FP is ~58.
More than a 5psi drop at WOT can cause problems.
Your pump might be going out but you need to use a gauge to find out.
I have had problems when FP goes in the 40's.
I have the Racetronix single intank for 98's it's worked well but I'll be pulling it out in a month or two and going to a hoodaddy external pump.
More than a 5psi drop at WOT can cause problems.
Your pump might be going out but you need to use a gauge to find out.
I have had problems when FP goes in the 40's.
I have the Racetronix single intank for 98's it's worked well but I'll be pulling it out in a month or two and going to a hoodaddy external pump.
Re: Fuel pressure and injector questions </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by MIGHTYMOUSE:
<strong> on a 98, the pump swap is pretty obvious and staight forward once you get into the tank and have a look around. i have pics on my website under fuel system just put one pump in there instead of two.
i have a charged air pump from ls1speed.com
it seems to be a favorite around here, at least for the forced induction crowd </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Is the charged air pump the regulator or the fuel pump?
I looked on LS1Speed’s web site and could not fine this item.
John
<small>[ February 26, 2003, 12:39 PM: Message edited by: JNorris ]</small>
<strong> on a 98, the pump swap is pretty obvious and staight forward once you get into the tank and have a look around. i have pics on my website under fuel system just put one pump in there instead of two.
i have a charged air pump from ls1speed.com
it seems to be a favorite around here, at least for the forced induction crowd </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Is the charged air pump the regulator or the fuel pump?
I looked on LS1Speed’s web site and could not fine this item.
John
<small>[ February 26, 2003, 12:39 PM: Message edited by: JNorris ]</small>
