Originally Posted by Chris99
Originally Posted by gomog
My WALBROs never came with a check valve.

The Walbro GSS342 we use for the M3W does not have a check valve.

Then I can stop searching. Ty.
Originally Posted by Rog G
That is the fuel pump, original fitment 93-98 Land Rover Discovery, p/n WFX101020, and yes prone to failure in both M3W and Discovery’s which is why it is recommended to replace the pump with a Walbro unit.

Do either of you have the maker/part# of the regulator?
Interesting. Some of those identical vehicles, with the same pumps, came with check valves and some did not. Can it be that some had redundancy built into their fueling systems pressure and some did not? In both cases it
suggests that there is another feature that could hold pressure. Normally, it is between a check valve and the regulator. Here is a generic EFI fuel pressure diagram..first I found on a 2 second internet search, It, like all others I find,
matches the MMC and their part task descriptions. (the rrows are not mine) I am going to search out what the poor 93-98 Disco people did when they had the same problem.

Originally Posted by RedThree
The pressure is maintained in the system by the constant flow from the pump to the restriction that is the pressure regulating valve in the fuel filter.

Yes! Between a check valve or when the pump is pumping, the regulator can set and maintain the pressure.

[quote=RedThreeIf there is a one way valve in the pump assembly it is a particularly rubbish one......and even with the dedicated non-return valve I fitted between the output of the pump and the engine
on my one, once the pump is off the pressure falls away fairly quickly, and yes, I do have a good fuel pressure gauge on my dashboard.

That isnot how EFI is ideally supposed to work, but the such vehicles will function. It takes over a day for my EFI system to lose much pressure. BTW, I too fit fuel pressure gauges to my Morgans, into the FSE
fuel pressure regulator's blanked off and unused side. I also wired my fuel pump differently, so, after long periods, I can run the pump and the pressure up before trying to start the car.
May I suggest you call FSE a super fuel pressure regulator manufacturer in the UK. If you get the right guy (not all are) he can cross reference the regulator you are using using and suggest a replacement. You will have a
much better and easily repairable component. That will might give you a sharper acceleration and allow you to determine whether you have the best pressure for the most fun. If not, merely set it to stock. In all cases, you
have a better quality and the manufacturer is at hand.

BTW, are you are aware of the symptoms of a faulty fuel pressure gauge?

Thanks for you help here. I am having fun.

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Last edited by gomog; 23/04/24 09:29 PM.