proper fuel pressure??

[idoari 10]

Hi,

 

i'm starting to diagnose my rough ideal in my 1,6 GTI. i connected the pump directly to a fully charged battery and connect a fuel pressure gauge to the inlet to the rail (after the fuel filter) and the pressure is about 42.5 psi when the engine is off (the maximum fuel pressure) and when i connect a hand vaccum pump to the fuel pressure reg. and set it to 20PSI, the fuel pressure is drop about 10 PSI to 32.5psi - i waited about 5 min in this state to see if the FPR is leaking (the hose than connect to the FPR is transparent) - no leaks of fuel and the Fuel pressure stayed 32.5PSI - so i supposed the FPR is fully functional. when i block the return hose (after the FPR) by  kinking it, the pressure rose to 60 PSI so i suppose the fuel pump is good as well.

 

is it normal in your option?

i want to make sure

 

thanks

Ido

[PhilNW 44]

I have always checked the fuel pressure directly after the pump, it supposed to be rated at around 45psi (3 bar)

 

Not sure how you got 60psi unless the gauge is incorrect

[idoari 10]

the pressure is about 43 event without the fuel filter (bypassed) and with the engine off (which supposed to put it on may pressure)

i've rolled out the pump being the problem by KINKING the return hose - hence why i've got 60 psi.

 

my thought are: since the pump COULD provide 60 psi (even if it by KINKING the hose) - the pump is OK (current my if i wrong).

the fuel filter is fairly new (2000 KM) and i tried to bypass it - same pressure - so it's must be OK either.

i think it's the FPR stack open - i just want to confirm it - the diaphragm is intact because it's hold pressure.

 

am i right?

 

[PhilNW 44]

As far as I know the standard Bosch pump is only capable of 45psi , it cant produce more than that,  is it the correct pump?  

Edited March 8, 2021 by PhilNW

[idoari 10]

Yes it the standard 993 bosch pump. This pump IS capable for more than 45 psi, the FPR is limiting it to 45 psi. 

 

As you propably know pressure  created by resisting to flow. The pump providing the fuel volume the restriction for this fuel volume creates the fuel pressure.

[bacardincoke 42 1 Cars]

Check out this French site, it's a mine of information and can be translated into quite a few different languages.

 

This is a link directly to the fuel pressure regulator but there's many, many more articles if you navigate around...

 

http://www.dethomaso.fr/article-fiche-pratique-injection-regulateur-de-pression-essence-67364121.html

 

 

[petert 590]

You need to check pressure before the rail, with vacuum compensation disconnected from the regulator, engine running. Thus if it has a 3 Bar reg, you should see 3 Bar.