2002 Moomba Mobius Fuel issues

[codydawson]

I have no idea if I am posting this in the correct place but hopefully there is someone on here who can help. I have had this boat for around 3 years and has a 5.7 indmar inboard set up on it. These boats are equipped with two fuel pumps which to my understanding one is a low pressure pump (lift pump) and one is a high pressure pump (injection pump). When idling the high pressure pump makes a whining noise which makes me think that it is starving for fuel and occasionally the boat will shut off, but the boat smokes slightly like it is running rich. What I have done so far is taken out the tank and cleaned it (due to water in the fuel). have replaced all the fuel lines up to the low pressure pump, and replaced both fuel water separators (one is before the low pressure pump and one is on the bottom of the high pressure pump), and the high pressure pump has been replaced as well as the injectors. I'm wondering if my low pressure pump is going and that is why my first high pressure pump has gone out but why is it running rich? Please help. There is no one that will work on these around.

 

[Fun Times]

Hi there, welcome to iboats!

Typically most low and some high pressure pumps have a screen located at the pump "inlet" fitting side that gets clogged up causing a whine sound or low PSI.

Knowing you had water and/or debris in the tank, you may have debris at the inlet screen/s.

Pull the pump fittings off and have a look. May as well practice on your old pump first, Let us know what you find and good luck.

If the screens are clean then you'll need to check you fuel pressure/s.

 

[codydawson]

I will try and pull the pumps tonight and see what I find. Would the screens be located somwhere within the pump? Because I know there isn't one where the hose connects.

 

[codydawson]

So yesterday I pulled the high pressure pump and looked at the screen and it was clean. Also read up on vapor lock but I have issues from the start when the fuel lines and pump aren't even hot so i'm hard pressed to think that this is the issue. Not sure what to check on the low pressure pump or if that is even the problem. Just a side note this boat has a in line fuel water separator and a nother one that is attached to the high pressure pump. Is that necessary?