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I have a 2016 Harley Fat boy. I recently had a no start issue and found that the fuel line inside the tank was leaking/broken. I decided to replace the fuel pump, lines and regulator while I was there. I put it all together but now the regulator purges all of the gas when I turn it on. I checked the fuel pressure and it has 55psi pressure for about a second then the regulator purges it all (sprays it into the tank, I can watch it). I figured the new part was bad so I tried the old part. Same thing. So I ordered another new regulator and it is doing the same thing. Any ideas?
The first sentence is separated by the photo but I did say 2016 Fatboy
So your saying that regulator sprays the entire time it is running? Because when it sprays I lose all fuel pressure (I checked it with a gauge)
I have no codes. So it almost has to be in the tank
Originally Posted by Max Headflow
Missing an O ring?
Fuel will gush out as long as the pump is running. Maybe a leak someplace else?
Model and year would help here.
Yeah, I view in dark mode so I didn't see the top. I highlighted the text at the bottom and read it. Set all your text to automatic color..
Yeah it sprays all the time but should, when pump shuts off, stop dropping at 55 to 60 psi . If you don't have any leaks then the only place it can go is back through the pump.. When the pump stops pumping, it should hold pressure.
So if it doesn't hold pressure, the regulator would be bad? Correct? Because that is all I can come up with but that means I have 3 bad regulators and that just seems odd.
QUOTE=Max Headflow;22050118]Yeah, I view in dark mode so I didn't see the top. I highlighted the text at the bottom and read it. Set all your text to automatic color..
Yeah it sprays all the time but should, when pump shuts off, stop dropping at 55 to 60 psi . If you don't have any leaks then the only place it can go is back through the pump.. When the pump stops pumping, it should hold pressure.[/QUOTE]
So if it doesn't hold pressure, the regulator would be bad? Correct? Because that is all I can come up with but that means I have 3 bad regulators and that just seems odd.
QUOTE=Max Headflow;22050118]Yeah, I view in dark mode so I didn't see the top. I highlighted the text at the bottom and read it. Set all your text to automatic color..
Yeah it sprays all the time but should, when pump shuts off, stop dropping at 55 to 60 psi . If you don't have any leaks then the only place it can go is back through the pump.. When the pump stops pumping, it should hold pressure.
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...
Last edited by MarlinSpike; Jun 21, 2025 at 08:35 AM.
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.
You stated three regulators changed - Time to look closer. Housing cracked or fitment, O-ring missing ect...
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 have a 2016 Harley Fat boy. I recently had a no start issue and found that the fuel line inside the tank was leaking/broken. I decided to replace the fuel pump, lines and regulator while I was there. I put it all together but now the regulator purges all of the gas when I turn it on. I checked the fuel pressure and it has 55psi pressure for about a second then the regulator purges it all (sprays it into the tank, I can watch it). I figured the new part was bad so I tried the old part. Same thing. So I ordered another new regulator and it is doing the same thing. Any ideas?
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..
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.
Last edited by MarlinSpike; Jun 21, 2025 at 10:06 AM.
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Fuel pressure regulator issue
