2004 Volvo Penta GXI 5.7 looses power at under load.

[Harp7397]

I have a 04 Caravelle with a Volvo Penta GXI 5.7, ran great last year and first time out this year and everything was great until I got out past the wake buoys and boat started loosing power under load and seems to have lean pop and stumble. I was able to stop and after sumbbling for a few minutes and bogging it cleared up and took off again and it did the same thing. It also had a loud whine that would come and go during this I am guessing the fuel pump. Boat runs great at idle and in the yard on a hose but only does this under load. Thanks for any assistance. I have changed and checked the fuel filter twice all clean and no water. Changed cap and rotor just for good measure but no change.

 

[dypcdiver]

I think you have a fuel problem which you have alluded to.
Check the screen of the fuel pump as it might have caught debris from your tank or even the paint problem. Failing that check the fuel pressures at the low & high sides of the fuel pumps.
Check this out

 

[ESGWheel]

Also check the screen on the pressure regulator which is on the fuel rail. If you do determine it’s a lack of fuel pressure due to a crapped-up system you can get back on the water with an aftermarket fuel pump for about $150 and send off your VP pump to Troy (same guy as in the video). He does VP pump rebuilding and at same time removes all the inside paint. Look for his other vids and you will find the one where he offers this service. As far as I know he is still doing it. Get your OEM pump back fm Troy, reinstall and keep the knock off one as an emergency spare. Here is the AM pump on Amazon link.

And for a fuel pressure gauge get one that screws onto Schrader valves. I have this one, link, but there are cheaper ones.

 

[Harp7397]

Thank you both I will get right on this and see if I can get it corrected!

 

[Harp7397]

Just an update, it was the paint chip issue so all replaced and runs like new. Thanks for the advice!

 

[ESGWheel]

Just an update, it was the paint chip issue so all replaced and runs like new. Thanks for the advice!

That is great news!

As part of the 'get the paint out' actions I did I ran across a VP bulletin on the pressure regulator about removing the screen and replacing with an E-clip. I was able to find a direct fit Bosch regulator and replaced the screen with the E-clip and it’s been working fine since beginning of 2020 season. Here is a link to my post about it which includes links for the items.