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Yes, I was thinking the housing, I can't see any cracks, but I realize that doesn't mean they are there.
This one reaches correct pressure then all of a sudden it is gone when regulator purges. So yes could be crack, or what if the pump is letting it back flow?
Grrr.. thanks. Confirmed what I thought. I was hoping for some other reason... More work to be done
Originally Posted by MarlinSpike
The system if working properly - Pump kicks on and pressurizes the system up to the injectors. ~58 psi. The pressure regulator bleeds off excess pressure, which is slight and should be very little fuel. Pressure holds at 55-60 psi. It should not continue to be bleeding fuel in the tank unless the pump is running and the bike not running, which is not how it operates.
Once the pressure is achieved, the pump turns off and holds the pressure. Mine holds the 58 for over half an hour when I have done checks.
The regulator should not bleed that pressure off continually if working correctly.
Regulators changed more than once - Time to look closer. Pressure regulator housing cracked or fitment, O-ring missing ect...
Yes, the pump does not have a control itself. Check valve for back flow, I would bet to hold the pressure from the pump to the regulator and hold the set pressure.
But my point was - after three regulators it's time for plan B.
It may be the housing that the regulator is held in. If fuel is still spraying out after the pump has stopped for more than a couple of seconds, that is not correct, and would not be holding the set pressure. Meaning that the Housing interface or O-rings could have issues.
Could also be the fuel line to nipple connection - those lines and clamps are a little tough for some people.
I think the pump itself does not have a separate check valve. At least the early delphi ones didn't.. The pump was a flexy vane type and the way the vane flexed kept it from spinning backwards and sealed off the pump.
Last edited by Max Headflow; Jun 21, 2025 at 05:20 PM.
Reason: add pic
Yes, I replaced all fuel lines. I had to. They were broken 😭
QUOTE=Max Headflow;22050393]The first part is very good but the second part is not clear enough and implies that the pump senses pressure. Nothing senses pressure. The pump simply runs to prime the system then stops after 3 to 4 seconds (time guessed) if the motor is not running. Last part is good.. The system may not be leaking from the regulator since 3 were tried. A good thing to know is how quick the pressure drops and if leaks observed.
The are 3 O rings that need to be in place. Was the fuel line to the bottom of the tank replaced?
I just took the picture without the screen to show where I think it is coming out I know where the screen goes
But I'm thinking maybe there's a crack that I can't see grrr thanks
QUOTE=98hotrodfatboy;22050426]Put the old regulator back in and see what happens.. The regulator in the pic appears to be missing some parts.. The screen is what supports the inlet O-ring..[/QUOTE]
Yes, I replaced all plastic lines. Specifically because that line to the bottom of the tank was actually broken
QUOTE=Joeblack33;22050754]Yes, I replaced all fuel lines. I had to. They were broken 😭
QUOTE=Max Headflow;22050393]The first part is very good but the second part is not clear enough and implies that the pump senses pressure. Nothing senses pressure. The pump simply runs to prime the system then stops after 3 to 4 seconds (time guessed) if the motor is not running. Last part is good.. The system may not be leaking from the regulator since 3 were tried. A good thing to know is how quick the pressure drops and if leaks observed.
The are 3 O rings that need to be in place. Was the fuel line to the bottom of the tank replaced?
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I know where the screen goes 
