Fuel check valve and the 3port fuel pump |
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
Fuel check valve and the 3port fuel pump |
brant |
Sep 10 2016, 07:54 AM
Post
#1
|
914 Wizard Group: Members Posts: 11,624 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains |
I think there must be a check valve built into the 3 port djet pump
I believe mine is not working (Hard starting symptoms) Has anyone pulled theirs apart? Pictures or a thread? I'm also wondering if adding an in line check valve would work? |
brant |
Sep 25 2016, 09:22 AM
Post
#2
|
914 Wizard Group: Members Posts: 11,624 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains |
Some details
I may get a better picture when I get home So on the 3 port pump there is a pressure blow off valve that opens a pathway for the pressurized fuel to bypass the output "D" fitting on the pump. I assume the original designers figure that when the hose feeding the injectors was already fully pressured to 29psi (built to that pressure by the regulator) that the pump was pushing against that head pressure and possibly running under load needlessly (wear to the pump gears?) What ever their original logic was, they created a blow off valve for the fuel to bypass that out put path and divert to the tank return pathway when the valve is open and doesn't get pushed by its 2springs back to the closed position, and the car/pump is turned off..... The residual fuel in the lines is sitting At 29psi and runs backwards in the circuit to drain through this open valve when sitting at rest There is a crimp cap on the pump Under the cap is: a cap gasket A large spring A spring plate/divider A small spring A rubber snapped into the piston (40 years old) And a piston My rubber broke (a bad pregnancy joke) The one end of the rubber creates the seal for the closed piston With the rubber missing the piston doesn't close and leaves this alternative pathway for fuel to drain backwards in the circuit when the pump/key is turned off You can pry the aluminum cap off of the pump and expose all of these parts I will look for replacement part alternatives when I get back home Out of town right now working on the racecar |
Lo-Fi Version | Time is now: 17th May 2024 - 03:09 PM |
All rights reserved 914World.com © since 2002 |
914World.com is the fastest growing online 914 community! We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ... |