General Rotary Tech Support Use this forum for tech questions not specific to a certain model year

Fuel Pressure Reg Issue or other Issue?

Old 11-22-17, 11:11 PM
  #1  
Full Member
Thread Starter
iTrader: (1)
 
Join Date: Apr 2014
Location: Edmonton, Alberta, Canada
Posts: 193
Likes: 0
Received 2 Likes on 1 Post
Fuel Pressure Reg Issue or other Issue?

While tracing another issue I have been having with my rotary, I checked fuel pressure, which opened up a new issue I didn't know I had for 3 years. I have 74PSI Fuel pressure at idle, and it drops to 68-70PSI at wide open throttle at redline. Removing the vac line to the regulator makes no change, and I am getting vacuum to it. At fuel pump prime, I am getting 55psi, and as soon as the pump shuts off, my pressure drops to 38 and holds there with the engine off. I connected the fuel pressure gauge tee'd into the fuel line between the fuel filter and fuel rail, so a plugged fuel filter would give lower pressure since I am reading fuel pressure after the filter.

Background info, this is mainly a S4 TII engine in a 93 B2200. The B2200 was originally EFI, I originally swapped a stock S4 NA motor into the truck in 2014, ran the original fuel pump for a few months, I found the fuel pump (which had 180,000 miles on it), was not supplying enough fuel pressure when the secondaries kicked on, so I changed it for a Supra fuel pump, ran that for a year, then I changed it out for a 340LPH pump last spring. I swapped the S4 TII engine in last winter.

I am running the stock fuel pressure regulator, and no pulsation dampener, stock B2200 rest of the fuel system, including the filter. Stock size rubber fuel hoses as well

I am thinking the crazy high fuel pressure is due to my fuel pump flowing more fuel than the regulator can handle, but has anybody else had this issue? I mostly see people add an adjustable fpr to increase fuel pressure for larger injectors, etc... Not due to a larger flowing pump.
befarrer is offline  
Old 11-23-17, 10:55 AM
  #2  
rotorhole
 
Join Date: May 2017
Location: retired rotorist
Posts: 700
Received 67 Likes on 63 Posts
what pump are you running? you'd have to have something insane like a 400lph pump to cause such a huge pressure rise.

also keep in mind, once you fix the issue you will have noticably less fuel in your tune across all RPM ranges.
insightful is offline  
Old 11-23-17, 10:27 PM
  #3  
Full Member
Thread Starter
iTrader: (1)
 
Join Date: Apr 2014
Location: Edmonton, Alberta, Canada
Posts: 193
Likes: 0
Received 2 Likes on 1 Post
I have this one, local shop carries this one, said they have had good luck with it.

https://www.performance-world.com/Fuel-Pump-p/643401.htm
befarrer is offline  
Old 11-23-17, 10:36 PM
  #4  
rotorhole
 
Join Date: May 2017
Location: retired rotorist
Posts: 700
Received 67 Likes on 63 Posts
thats still far too much fuel for the stock fuel pressure regulator and likely could be your problem.

you need to omit the stock FPR and put in a larger volume regulator RRFPR on there.
insightful is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: