BenzKraft

Greetings!

Does anyone know if there is a fuel pressure regulator and/or a check valve in the in tank sending unit (left side of tank) or with the in tank fuel pump assembly (right side of tank)? I tested my in tank fuel pump and it pushes 60psi but once the pump stops priming I loose pressure completely, down to 0 psi. I'm guessing it's the in tank pressure regulator that isn't holding pressure or is leaking or maybe the check valve (if there is one) that is worn out/leaking.

Thanks for the help in advance!

Micah / AF1 Rac

kajtek1

You must be talking about check valve?
Whatever it is, the only thing you can buy is whole pump assembly (some models need whole new tank), but if you like DIY, take it apart and clean.
Be careful with installation as saddle tank uses maze of tubing with Venturi effect to transfer fuel from 1 side to the other and small misalignment makes fuel sitting on passenger side, when pump on driver side runs dry.

Micah / AF1 Rac

BenzKraft

So from extensive research I found out that there are check (ball) valves within the in-tank fuel pump, internal in the motor. I also found out my fuel pressure loss isn't as a result of these valves in the in-tank pump... the fuel isn't returning back to the tank from the supply line which proves these check valves are seating properly and since fuel supply pressure is around 60psi my in-tank pump is operating properly. I pinched off the supply line to the fuel filter after it primed and my make-shift pressure gauge still dropped completely to 0 psi. I did another bleed off test with the engine off, letting the fuel system prime and pinched the return line after the fuel rails and the pressure stopped dropping so this indicates the pressure loss is likely happening at the pressure control valve (regulator) on the fuel rail which should normally be closed at startup.

My next step is to see if replacing just the regulator works instead of the whole rail like the dealership wants everyone to do. The difference is $700+-. (Dealership wants $938 CAD for new rail with regulator). The dealership says changing the regulator (instead of whole assembly) doesn't work or fails so they will only change the complete rail with a new regulator. I'm going to go against the grain to see if this is true and report my findings. I thought I'd follow up for the benefit of others in this forum.

Cheers

BenzKraft

I looked into replacing just the regulator on the fuel rail but decided to replace the whole rail assembly in order to prevent future leaks/issues. Replacing just the regulator, although possible, isn't recommended. The chamfered mating surfaces between the new regulator and the original rail doesn't seal properly due to imperfections after removing the old regulator and the torque required is very precise: needs to withstand 2500bar and yet not be over-torqued so as to damage the sealing surface. I found a fuel rail (6420702195/6420780249) supplier in Germany at half the cost of the North American dealerships. PM me if anyone needs one and I'll send you the link.

newtoblue

I’d like to get that suppliers information for the fuel rail. Thank you

sprinterhightop

try to install in line check valve.witch line to install the return or the fuel feed line?