2004 f225

[Morgancody15]

need some advice. I have a 2004 f225 boat runs great all the way up to 5200 rpm. If a demand any more fuel it will fall on its face for a half second or so and lose 1000 to 1500 rpms. If I dial it back down to 5100 it will run all day with no issues. I’m assuming it’s either a vst filter , injectors, or low pressure fuel pump not cycling correctly. Any advice before I engage that parts cannon to it.

[fairdeal]

first, it's easy, and free,
to try to find out if the problem is the VST running empty:

you have a primer bulb, and with that bulb you should be able to fill the VST,
at which point the float closes the needle valve,
and you can tell because the bulb feels 'hard'.

So get another pair of hands,
and as the boat gets to that 5200rpm point,
keep the VST full with the bulb.

If that removes the rpm limit,
then look into the low pressure system
to find out why it is not keeping up.

But if that doesn't help -
if despite the VST being full of full,
the engine still bogs,
then the problem is with the high pressure system
(and likely that VST screen)

[Morgancody15]

Thank you very much I will test that as soon as possible. I know that the vst screen has probably never been changed or cleaned. I just bought the boat a few months back. But also interesting enough my second or third trip on the boat I blew my fuse to my low pressure fuel pump which has me thinking there is an issue with it.

[fairdeal]

second or third trip on the boat I blew my fuse to my low pressure fuel pump which has me thinking there is an issue with it.

hmm.
If I was to theorize a cause for that,
it would be excessive strain on the pump
due to a clogged shut pressure control valve

although that would not explain rpm restriction;
since (until the fuse blows) higher pressure output of the lift pump
would certainly be able to keep the VST full...

[Morgancody15]

Also when I was talking about the motor losing power it will only do it for a half second to a second then rpms will shoot back up run great for a few second then do it again. So on and so fourth until I dial it back down to 5100 rpm. I’m still two weeks offshore until I can get home to test. Thank you for your continued advice and support

[Morgancody15]

I believe I found the issue. I tore the vst down and found this 0418DA12-1427-4211-A22C-D536D7FAACFC.jpegit seems the grommet on the high pressure fuel pump has failed and I believe that could be causing the loss of power intermittently

[oldmako69]

That's a distinct possibility. It's allowing just enough fuel to leak out. Before this pic, I would have gone with VST screen or fouled F.I.

The good news is that rubber grommet is only about 200 bucks from Yam. (JK).

[Morgancody15]

I know right… also can anyone give me a part number for the low pressure lift pump. I work offshore and am not home to pull it myself. I figured it would be good to go ahead and replace . The high pressure seems to be in good working order

[pstephens46]

Am I missing something? You have the pic of the high pressure pump? You want to replace grommet and low pressure pump?

[TownsendsFJR1300]

Capture.JPG


Part # 16


https://www.boats.net/catalog/yamaha...jection-pump-1



.

[oldmako69]

https://www.amazon.com/Mercury-Outbo.../dp/B00XYXX8KY

I put one of these on my engine. Paid about 80 bucks vs the YAM for 500. Boat ran just fine with it.

[Morgancody15]

Thanks for all the help everyone. I ended up replacing high pressure and lift pump and did a vst rebuild as well as replaced all the fuel filters . Boat runs amazing and have not had a issue yet