• Mustang Forums
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • Classic Mustang Specific Tech

Whats a good fuel pump?

  • Thread starter Thread starter stangman67
  • Start date Start date Jun 17, 2007

stangman67

Member
Feb 8, 2003
294
0
17
connecticut
Jun 17, 2007
#1
  • Jun 17, 2007
  • #1
I am currently running a Holley mecanical pump, the 110 gph version i think, and having some psi issues. I have a typical holley regulator (chrome) with the dual outlets. At startup, i have 6.5 psi, but after it heats up it drops to 4.5-5 psi. As I blip the throttle, watching the gauge on my log fuel rail, it definitly drops to like 3.5-4 psi. The issue is that I have a nitrous system with fuel psi saftey cutoff, and the only bottle i have ran through it has been a very surging feeling. I always assumed the bottle was filled wrong, but now with my new gauge, I believe that the saftey was turning on/off repeatedly, and that was my surging feeling.
So, my question is what fuel pump/regulator should i run. I tried adjusting the regulator, but the most i could get was 5ish when hot. I have the stock 5/16" pickup, 3/8" hardline, and 6an line from the regulator to the carb. I had an electric pump before, but it was kinda loud and pulsated annoyingly, so I would like to stay mechanical. Could the 170 gph holley pump be sufficient? I know i should have an aux. fuel pump for the nitrous, but its a 100 shot, and my stock pickup kinda limits a 2 pump system. I find it odd the current pump cant supply its rated psi (6.5-8) even at idle. Thanks for the advice.
Mike
 

brianj5600

Active Member
Sep 19, 2003
1,964
2
39
Middle TN
Jun 17, 2007
#2
  • Jun 17, 2007
  • #2
Is the guage liquid filled? In the engine compartment? Search for hueypilot and fuel pressure. He had the same issue and traced it to the glycerin filled guage varying with temp.
 
M

mustangdave

My rearend needs a stud and two nuts.
Founding Member
Feb 26, 2002
2,976
1
56
North Carolina
Jun 18, 2007
#3
  • Jun 18, 2007
  • #3
I don't think that pump is meant to be run with a regulator: check the website.
 

jcode68

Active Member
Jul 15, 2003
892
1
29
Massachussetts
Jun 18, 2007
#4
  • Jun 18, 2007
  • #4
I have the same fuel pump without a regulator because it was supposed to be calibrated to work with a carb and not need a regulator. The reality was, PSI was around 11 PSI continuous and reulted in me posting this thread:

http://forums.stangnet.com/showthread.php?t=705147

I solved my problem this weekend by plumbing in the Holley 12-803 regulator. Guage now reads right at 6 PSI like it should. I haven't checked it after warming up to full temp, but I will. So my experience is you need to run a regulator with the Holley 110 GPH mechanical pump.
 
R

ron67fb

Founding Member
Aug 3, 2001
1,117
0
36
SF Bay area, CA
Jun 18, 2007
#5
  • Jun 18, 2007
  • #5
stangman67 said:
At startup, i have 6.5 psi, but after it heats up it drops to 4.5-5 psi.
Click to expand...
I had that problem and it turned out to be vapor lock. The radiator fan was blowing hot air onto the line that went from the pump to the carb. I sprayed water on the fuel line and watched the pressure go back up. As the water evaporated the pressure would drop again.
 

stangman67

Member
Feb 8, 2003
294
0
17
connecticut
Jun 19, 2007
#6
  • Jun 19, 2007
  • #6
If it was vapor lock, how did you correct the problem? I just cant believe that the pressure drops to 3ish when i goose it with my hand. I have had an edelbrock pump fail on me already, and i am starting to think that most aftermarket pumps are a gimmick, and they are all pos.``
 
You must log in or register to reply here.

Similar threads

M
01 mustang 3.8 fuel pressure issue
  • Mhaley2006
  • May 29, 2026
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
0
Views
94
1996 - 2004 SN95 Mustang -General/Talk- May 29, 2026
Mhaley2006
M
C
98 gt fuel pressure issues
  • chasecollier1984
  • Jun 2, 2026
  • SN95 4.6L Mustang Tech
Replies
0
Views
55
SN95 4.6L Mustang Tech Jun 2, 2026
chasecollier1984
C
D
Fuel Erratic Fuel Pressure 1985 GT
  • DienstXIV
  • Jan 14, 2026
  • Fox 5.0 Mustang Tech
Replies
16
Views
641
Fox 5.0 Mustang Tech Jan 16, 2026
AeroCoupe
Fuel Anyone know a part number for a 3/8" inlet/outlet efi quick connect fuel filter that would fit the stock foxbody location?
  • rednotch
  • Dec 8, 2025
  • Fox 5.0 Mustang Tech
Replies
2
Views
261
Fox 5.0 Mustang Tech Dec 8, 2025
rednotch
I
1994 Cobra - Fuel Pressure Drops Revving at Idle
  • IconicSilverGT500
  • Apr 11, 2026
  • 1994 - 1995 Specific Tech
Replies
16
Views
413
1994 - 1995 Specific Tech Apr 24, 2026
Mcmahst
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • Classic Mustang Specific Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?