Originally Posted by Chris99
Thanks Gomog, To confirm the fuel pump is in the (right hand) fuel tank and neither the original pump nor the Walbro conversion in tank pumps have pressure control.
The fuel is pumped to the injectors and the fuel filter in the return line has the pressure control - call it a valve or regulator as you wish. This is preset at 58 psi and monitored via the
ECU so if the pressure drops the spark is cut off.

Thank you Chris!

A FUEL PRESSURE REGULATOR and a check valve are different. The regulator is a spring-loaded pressure-activated diaphragm system that maintains the pressure in a fuel system to a pre-set
value above manifold pressure, particularly in a fuel injection system. It sends unused fuel back to the fuel tank..so FI systems normally had a second fuel flow returning fuel to the tank. It largely
functions as you say but many of us use adjustable ones like FSE.

Earlier Morgan EFIs can use them to:
1. create a steeper curve of fuel supply on hard demand, increasing acceleration when one puts the foot to the floor.
2. Adjustable ones can increase fuel pressure across the range, easily allowing a greater supply for larger capacity engines, like mine.

A CHECK VALVE merely stops fuel from moving in one direction, in this case backwards though what should be only a feed line. Without one, your feul will drain backwards every time your pump is
off or gravity (angle of the car) allows it. For example, you have one form of check valve being used (in the diagram) as a turnover valve. If you turn over, it prevents the fuel tank from emptying onto drivers when
upside down. They became mandatory decades ago, though many older mogs don't use them though they DO vent their tanks. Yours pumps the fumes into a charcoal canister. Often the regs of two
different governments fight for commons sense. ooo

You got me interested enough for the first time to examine the M3W stuff I archived. I enjoyed it! I made a simple diagram of the fueling area from the M3W parts books I have.
Below.

Questions.
1. I see a lot of rubber section interfaces between metal (?) pipes and other metal pipes or components. Is that the case?

2. Are the two colored sections of the to-and-return-the engine fuel feeds metal or hose?

A check valve cost is negligible and installation simple with an unpressurized system. It will prevent leakage backwards, which is the issue here unless the technician was
mistaken. Why not? Redundancy is prudent in this area. No need to take it off regardless of the result. I and many others had this EFI leak down problem until we installed
them. The risk is 2 quid.

Lorne

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