5.0 GXI normal fuel pump whine only when in water?

StingrayMike

Petty Officer 1st Class
Joined
Aug 17, 2014
Messages
355
As stated above, I only hear the whine when boat is in the water. I assume because it is due to more load needed to turn prop compared to in the driveway with hose water hooked up for cooling?
sitting in the driveway, no noise what so ever.
in the water at idle, noise is low, but when speeding up, it gets louder and more high pitch, so it is speed/ rpm related.
boat operates fine, no cutting out at full throttle, gets up and goes.
I have taken apart the fuel pump, checked for debris in the screens, nothing.
is this normal?
its not really loud, but just enough to make me wonder.....

thanks
 

Dave-R

Chief Petty Officer
Joined
Mar 18, 2008
Messages
441
If you don't have any whine when using the muffs, but have noise in the water, I think you might have a restriction in the fuel cell cooling lines. Or could be one of the fuel pumps getting ready to crater. Check the hoses, then do a pressure check on both fuel pumps if you don't find a blockage. The high pressure pump will squeal, if the low pressure pump does not put out 5-8psi. You would be surprised how hot the engine compartment can get, and gasoline hates heat. the cooling lines are there for a good reason. This may also be an indication of your sea water impeller needing to be replaced, having inadequate flow. Dave-R
 
Last edited:

Dave-R

Chief Petty Officer
Joined
Mar 18, 2008
Messages
441
Just from my experience, the first time I pulled apart the fuel cell, I did not find the screens. They were covered with black paint. Also you can have an air leak around the fuel filter, that will starve the pumps. I pulled and cleaned the anti-syphon valve on the tank also. Wouldn't hurt to check these things. Dave-R.
 

StingrayMike

Petty Officer 1st Class
Joined
Aug 17, 2014
Messages
355
Its been abit since you posted last, haven't had any time for the boat.
if the impeller was bad, wouldnt the engine over heat?.
I FINALLY plan on tackeling this issue. I will defiently check those things out.
I already took apart the fuel pumps, screens were in place and clean. Inside of the pumps were clean.
1st thing will be check fuel pressure, need to stop by harbor freight and get a gage
 

StingrayMike

Petty Officer 1st Class
Joined
Aug 17, 2014
Messages
355
I.did a pressure check on the low see side pump, was putting out 10psi. Wasnt able to check hi side, didnt have the right size fitting.
thought I would check the impeller, that turned into afiasco. Couldnt get the allen wrenches in the opening to loosen them up.
got to hot and I was done by that point, will have to try again later.
 
Top