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1998 95th Anniversary FLHTCUI and a 2019 Fat Bob 107
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Discussion Starter · #1 ·
Hi guys,
I've traced my starting issues to the fuel pump, and one is on order. I've watched many YouTube vids about the subject and now have a very good idea how to do this myself, but in all the vids I've watched, there is no reference to the fuel pressure regulator on my year and model.

Can anyone tell me where the fuel pressure regulator is located? I'm assuming it's within the fuel tank, but I would like to have a good idea where before I crack open the tank plate and start rummaging around.

Thanks in advance,
Bob
 

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Magneti Marelli fuel pressure regulator is mounted to the rear bottom of the throttle body below the injectors not inside the tank like the Delphi EFI system.
My question to the OP is what he's going to do about the internal fuel hoses ? Those parts are obsolete !
I'm wondering if the OP did a fuel pressure test to determine that the pump has failed.
 

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1998 95th Anniversary FLHTCUI and a 2019 Fat Bob 107
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Discussion Starter · #3 ·
Magneti Marelli fuel pressure regulator is mounted to the rear bottom of the throttle body below the injectors not inside the tank like the Delphi EFI system.
My question to the OP is what he's going to do about the internal fuel hoses ? Those parts are obsolete !
I'm wondering if the OP did a fuel pressure test to determine that the pump has failed.
I do have the Magneti Marelli system and will look for that pressure regulator as you said.
I haven't gone into the tank yet to see what hoses are present. I hope I can use readily available high-pressure fuel injection hoses or that the existing ones are serviceable.
Did not do a pressure check because in the past, when the bike was running, switching the bike ON (key on, switch on) would result in an approximate three-second 'buzz', which was the pump pressurizing the system. That sound is no longer present, so a failed fuel pump is highly suspect.
Update: I actually do have voltage to the pump from the ECM. I found out the ECM only delivers voltage for three seconds or so after key on, switch on or until the pump has finished pressurizing the system, then the pump goes silent until more fuel pressure is demanded.
 

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Check to make sure you have a good ground. Put your probe/test light, not a meter, on the ground side of the pump, switch it on and see if you get batt voltage. If you do you have a bad ground. The reason not to use a meter is if you do have a bad ground you could hurt your meter putting it in series with the load. Follow the ground wire all the way back to ground to make sure it's making good contact. Just in case it's not the pump...
 

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OP it's more likely that one or more hoses in the tank are leaking. By the way those in tank hoses are special convoluted tubing specific to the application and are single use only. The fuel filter is also inside the tank connected to the pump via convoluted tubing.
You can see the in tank schematic at Ronnies Parts Finder at Ronnies H-D website.
 

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1998 95th Anniversary FLHTCUI and a 2019 Fat Bob 107
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Discussion Starter · #6 ·
OP it's more likely that one or more hoses in the tank are leaking. By the way those in tank hoses are special convoluted tubing specific to the application and are single use only. The fuel filter is also inside the tank connected to the pump via convoluted tubing.
You can see the in tank schematic at Ronnies Parts Finder at Ronnies H-D website.
Schmidty,
Thanks for this information! It took me exactly to where I needed to go. An additional question: Do I have to raise the back of the fuel tank to gain access to the pressure regulator? Since I'm getting one in the Quantum kit, I figured I would replace it.
Thank you,
Bob
 

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1998 95th Anniversary FLHTCUI and a 2019 Fat Bob 107
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Discussion Starter · #7 ·
Check to make sure you have a good ground. Put your probe/test light, not a meter, on the ground side of the pump, switch it on and see if you get batt voltage. If you do you have a bad ground. The reason not to use a meter is if you do have a bad ground you could hurt your meter putting it in series with the load. Follow the ground wire all the way back to ground to make sure it's making good contact. Just in case it's not the pump...
Thanks, I'll do that.
Bob
 

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Schmidty,
Thanks for this information! It took me exactly to where I needed to go. An additional question: Do I have to raise the back of the fuel tank to gain access to the pressure regulator? Since I'm getting one in the Quantum kit, I figured I would replace it.
Thank you,
Bob
I suggest removing the tank because the throttle body gets removed, much easier with the tank out of the way. The regulator can be removed with the throttle body in place but you're that far into this that the intake seals should get replaced and the throttle body gets removed for that.
 

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Discussion Starter · #9 ·
I suggest removing the tank because the throttle body gets removed, much easier with the tank out of the way. The regulator can be removed with the throttle body in place but you're that far into this that the intake seals should get replaced and the throttle body gets removed for that.
Thanks for this. Much appreciated.
 
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