The erikgross method revisited... - 3000GT/Stealth International Message Center
3000GT/Stealth International 3000GT/Stealth International
 

Auto Insurance

» Featured Product
Wheel & Tire Center

Go Back   3000GT/Stealth International Message Center > Modifications and Technical Support > Advanced Technical Discussions

3SI.org is the premier Mitsubishi 3000GT Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools
Old 12-07-2008, 10:51 PM   #1 (permalink)
Verified Seller
 
RealMcCoy's Avatar
 
Join Date: Jan 2006
Location: Medford OR
Drives: 92 RT/TT, 96 Cobra
RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3
Feedback Score: 50 reviews
Default The erikgross method revisited...

I made a post about this last week in general that sparked some interesting discussion, but it was never intended to be a case study/searchable resource... More of a "woot, look what I found" thread.. That thread can be found here:
https://www.3si.org/forum/f1/you-guys...6/#post5154453

Cliff notes of other post:

1: I install Supra pump in my car.
2: I think I'm really smart wiring in the stock resistor to keep from overrunning my stock FPR..
3: I'm not smart enough to search, and discover the pitfalls of this plan until AFTER I experience them myself..
4: I'm bent because it "should" have worked.. and go on a mission to find out why it didn't..

Now there are several methods of wiring a fuel pump that are attributed to Erik's work... For the purposes of this discussion, it is solely the practice of wiring in the stock fuel pump resistor to slow down a hotwired pump at slow engine speeds.. My entire fuel system is wired as standalone from the stock wiring. I used two relays signaled from the MPFI and the ECU.. Even the resistor is fed from the hotwire. Here's a diagram of my system:



From reading the old threads, Erik gave up on the idea because there was an obvious fuel pressure variation between the low and high speeds that screwed with the fuel trims and would cause drivability issues like lean spots right before the transfer... These are the same symptoms I experienced.

Many of you will say "why bother.. Put in and aftermarket FPR" And you would be justified in that position... But I'm far too stubborn to let a solution lay undiscovered. And I had a pretty solid theory about what was going on. (and wasn't about to take a couple hundred bucks away from the white car build if I didn't have to)

So here is the Data I gathered: (bench tests w/stock regulator)

The stock pump hotwired at approx 13.6Volts, draws 10 amps making 45 psi (w/no vacuum)
The Supra pump under the same conditions draws 14 amps and makes 50 psi(overrunning the FPR)

Deadheaded,(up against the internal bypass) the stock pump draws 12 amps making 90 psi.
Under the same conditions the Supra pump draws 20 amps making 100 psi.

Conclusion: the supra pump is a huge power hog...

On to my car... Why are we getting the pressure fluctuations?

KOEO, battery charger maintaining 13.6v, jumper relay to hotwire mode: The installed Supra pump screaming along at 7500rpm, drawing 14-15 amps, and overrunning the FPR...



Jumper the resistor on line: The supra pump gets the wind knocked out of it.. Slows down to 3500rpm, drawing 7.5 amps... At this speed it will make less than 50 psi deadheaded... Starting the car, I discovered that on a snap throttle the pressure would drop, rather than go up like it should. The Supra pump simply could not supply enough fuel to run the car while turning that slow..



Conclusion: Too much resistor for that pump...

Now what to do about it..? I already had a plan... I wired a second stock resistor in parallel to the original, cutting the resistance in half.




Results:

5000 rpms, 10amps, normal fuel pressure(no overrun), and able to make 80 psi deadheaded... WOOT! I win!



I've been driving it around for a week looking for any signs of fuel control or pressure issues. I have to call this one a fix..

Thanks for reading..

Larry.
__________________

Last edited by RealMcCoy; 12-14-2008 at 08:31 PM.
RealMcCoy is online now   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 12-14-2008, 08:32 PM   #2 (permalink)
Verified Seller
 
RealMcCoy's Avatar
 
Join Date: Jan 2006
Location: Medford OR
Drives: 92 RT/TT, 96 Cobra
RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3
Feedback Score: 50 reviews
Default Re: The erikgross method revisited...

Added pics to save thread hopping....
RealMcCoy is online now   Reply With Quote Quick reply to this message
Old 12-22-2008, 09:25 AM   #3 (permalink)
Keep'n 'em spooled
 
Turbo Powered's Avatar
 
Join Date: Nov 2003
Location: PA
Drives: at high g's
Turbo Powered Level 1Turbo Powered Level 1Turbo Powered Level 1
Feedback Score: 74 reviews
Default Re: The erikgross method revisited...

Beautiful !! + rep

I will be duplicating your setup. I just can't see running the FP at hotwired voltage all the time when it's not needed, it certainly has to shorten the life of the pump. I don't drive my car to work the way Chris does, lol, although I'm actually jealous he can drive that way where he lives.

Really glad I saw your post because I would have started out with the stock resistor setup and had the driveability and lean issues you described.
__________________
Turbo Powered is offline   Reply With Quote Quick reply to this message
 
Old 12-22-2008, 05:39 PM   #4 (permalink)
the 3S whisperer
 
gltasn's Avatar
 
Join Date: Apr 2008
Location: alaska
Drives: 95 mitz 3kgt vr4
gltasn is an unknown quantity at this point
Feedback Score: 13 reviews
Default Re: The erikgross method revisited...

am i too understand that since i have a upgraded fpr that i need not worry about this? great work though, you are very tenacious!
__________________
"If I was as slow as you, they'ed bury me!" terry canfield(dad)
gltasn is offline   Reply With Quote Quick reply to this message
Old 12-22-2008, 05:45 PM   #5 (permalink)
Verified Seller
 
RealMcCoy's Avatar
 
Join Date: Jan 2006
Location: Medford OR
Drives: 92 RT/TT, 96 Cobra
RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3
Feedback Score: 50 reviews
Default Re: The erikgross method revisited...

Quote:
Originally Posted by Turbo Powered View Post
Beautiful !! + rep

I will be duplicating your setup. I just can't see running the FP at hotwired voltage all the time when it's not needed, it certainly has to shorten the life of the pump. I don't drive my car to work the way Chris does, lol, although I'm actually jealous he can drive that way where he lives.

Really glad I saw your post because I would have started out with the stock resistor setup and had the driveability and lean issues you described.
It's hard to see in the pictures, but if you want to mount it the same way I did, flip the mounting bracket over on the second resistor, and bolt the original on with a much longer bolt, giving you room for a spacer and nut to mount the second one..


Quote:
Originally Posted by gltasn View Post
am i too understand that since i have a upgraded fpr that i need not worry about this? great work though, you are very tenacious!
You understand correctly... The aftermarket pressure regulators won't be overrun by a hotwired Supra pump, so you should have no problems....
RealMcCoy is online now   Reply With Quote Quick reply to this message
Old 12-23-2008, 08:29 PM   #6 (permalink)
Wrenchmonkey #839
 
John Monnin's Avatar
 
Join Date: May 2000
Location: Granger, Indiana
Drives: Milfs crazy
John Monnin Level 2John Monnin Level 2John Monnin Level 2John Monnin Level 2John Monnin Level 2
Feedback Score: 29 reviews
Default Re: The erikgross method revisited...

Great idea.

Did you measure the resistance in the stock resistor?
It might be worth looking into a smaller resistor, I am always looking to gain space under the hood.

The double resistor idea is still great because it looks so stock
__________________

Solidworks models of 3S engine parts: http://www.wrenchjockey.com/Images/Solids/3000gt2005/
John Monnin is offline   Reply With Quote Quick reply to this message
Old 12-23-2008, 10:52 PM   #7 (permalink)
Verified Seller
 
RealMcCoy's Avatar
 
Join Date: Jan 2006
Location: Medford OR
Drives: 92 RT/TT, 96 Cobra
RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3
Feedback Score: 50 reviews
Default Re: The erikgross method revisited...

Quote:
Originally Posted by John Monnin View Post
Great idea.

Did you measure the resistance in the stock resistor?
It might be worth looking into a smaller resistor, I am always looking to gain space under the hood.

The double resistor idea is still great because it looks so stock
I don't remember if I actually measured it with an ohm meter or not... You can easily calculate the resistance from the max current the resistor can flow.(25 amps at 13 volts for both, I think that was in the other thread) That calculates to just a little over 1 ohm.

I thought about using a different resistor... When I was testing the single, as it was being overworked, it was doing double duty as a shop heater... It mellowed out after doubling it up, but that was incentive enough for me to keep the heat sink...
RealMcCoy is online now   Reply With Quote Quick reply to this message
Old 06-03-2009, 01:27 AM   #8 (permalink)
Forum Member
 
Join Date: Sep 2001
Location: vancouver b.c.
Drives: 99 nosed 93TT
bad84kat is an unknown quantity at this point
Feedback Score: 0 reviews
Default Re: The erikgross method revisited...

Is this still working good? An AFPR and this double resistor method seems like it might be a good combo for life/reliability.
__________________
99 nosed 93TT
bad84kat is offline   Reply With Quote Quick reply to this message
Old 06-03-2009, 01:35 AM   #9 (permalink)
Verified Seller
 
RealMcCoy's Avatar
 
Join Date: Jan 2006
Location: Medford OR
Drives: 92 RT/TT, 96 Cobra
RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3RealMcCoy Level 3
Feedback Score: 50 reviews
Default Re: The erikgross method revisited...

Quote:
Originally Posted by bad84kat View Post
Is this still working good? An AFPR and this double resistor method seems like it might be a good combo for life/reliability.
Yes, I've been very happy with it. I haven't tried it with bigger injectors and an AFC yet, but that will happen soon. I'll report my results.
RealMcCoy is online now   Reply With Quote Quick reply to this message
Old 06-05-2009, 08:40 PM   #10 (permalink)
mdb
Forum Member
 
Join Date: Feb 2004
mdb is an unknown quantity at this point
Feedback Score: 0 reviews
Default Re: The erikgross method revisited...

Quick question, if I read correctly the supra pump hesitated beause the lower juice level wasn't enough for it to operate correctly, causing hesitation due to a lean condition before it kicked to full juice...........does the walbro 255 suffer from the same problem? I'm about to rewire my walbro but don't have the money for an AFPR, so I'd like to do it with the low/hi modes on it........thanx!
mdb is offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

  3000GT/Stealth International Message Center > Modifications and Technical Support > Advanced Technical Discussions

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the 3000GT/Stealth International Message Center forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Free email addresses do not work(yahoo, hotmail, gmail,...)
We are currently being blocked by AOL so any AOL based address may not work(aol.com, aim.com, netscape.net, cs.com)
Email Address:

Log-in


Thread Tools

Posting Rules
You may post new threads
You may 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 On
Trackbacks are On
Pingbacks are On
Refbacks are On


Powered by vBadvanced CMPS v3.2.2

All times are GMT -5. The time now is 04:37 PM.



Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.1
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
 

Garage Plus vBulletin Plugins by Drive Thru Online, Inc.