2005 225HPDI-Low Fuel Pressure

[MN Phoenix]

Hey Guys,

I was running down the river last weekend and at about 4800rpm my motor started surging and an alarm came up on my lowrance "low fuel pressure". The motor has been running really rough at idle and likes to kill for the last year.

Does this sound like an injector or fuel pump issue? If its the injectors I can save myself some labor by pulling them and sending them in. A fuel pump would be out of my range I believe. Just curious if I should take it in or try getting the injectors done first.

FYI, I changed the filter on the port side of the block last month and the engine has 240 hours.

Thanks

[BuzzB8]

You can get the fuel pump kits for next to nothing. Have you removed the screws holding them to the engine and pumped the fuel bulb (gently) to see if fuel leaks from the back of the pumps? See the post pinned to the top.

[toledo freak]

have you changed the filter inside the vst and also the metal strainer filter after the vst???? if not do it!! these should be changed 100hrs are you will end up having to send off your high pressure pump$$$$$$$$$$

[dward51]

X2 on VST

I would start there and also the medium pressure filter (silver canister just after the VST) if they were not previously done. Fuel starvation at upper end of RPM's is one of the first signs of VST clogging issues. If you are careful you can often clean and resuse the VST filter and the gasket seal. I would have a replacement in hand (with gasket) just in case you can't clean it or damage the gasket as it is very thin.

[spider1]

The first thing that you should do is connect a gauge to the schrader fitting on the vst. Turn on the key and you should have a reading of 50psi. Then turn off the key and the pressure should drop to 43 psi after 5 seconds. If that does not pass then open up the vst. If that passes then the high pressure fuel pump will have to be looked at. The low pressure reading off of your lowrance is the high pressure pump and there are no cheap rebuild kit for that. At idle the high pressure should be 900+ psi and up and running over 1000 psi. If you put a Lowrance LMF-400 or 200 on your dash you can read the high pressure as you are running down the lake.

[MN Phoenix]

Thanks for the replies guys, I hope to try some of this stuff over the weekend.

My Lowrance was reading about 970psi at Idle and 1017psi at WOT.

[spider1]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by MN Champion &raquo;</td></tr><tr><td class="quote">My Lowrance was reading about 970psi at Idle and 1017psi at WOT.</td></tr></table>

After the low pressure alarm??

[MN Phoenix]

The WOT was down to about 1000.

[dward51]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by spider1 &raquo;</td></tr><tr><td class="quote"> The low pressure reading off of your lowrance is the high pressure pump and there are no cheap rebuild kit for that.
</td></tr></table>

Don't forget about the filter screens in the high pressure pump that do clog and can be cleaned. I don't think Yamaha has covered these screens in their service manual (almost like a "secret" unmentioned filter).

For photos of what I'm talking about follow this link and go about half way down the page. This guy (Gringo) lives in the islands and has to do it all himself - no Yamaha tech at all. It started out as a rebuild of his 300HPDI due to water ingestion, but page 23 of the thread covers these filter screens and how to remove and clean them. Link should take you to the correct page, just scroll down.

http://www.thehulltruth.com/bo....html

[Rich Z]

Those little screens (item 21) look exactly like injector filter baskets we use in many injectors after flow testing. Got thousands of them at Brucato. That is some contraption he rigged up to test fire that injector. The one thing I would suggest for him is to measure each test fire on a gram scale and compare to the other injectors. Similar test method to ours just that we are little more high tech with equipment. Ecu output calibrated to a 100th of a volt, test fluid specific gravity, fluid temperature, injector operating temperature and test fire measurements measured to 100th of a gram at 2mils and 5mils. All these variables affect how much fuel is flowing through an injector. Brucato does like no one else!

[MN Phoenix]

Ok, so I tore everything apart and decided to replace the strainer, vst filter, and gasket. Too bad the dealership was closed saturday when I went to get the parts. I ordered them online and will be expecting them next week. Am I on the right track here?

[MN Phoenix]

I replaced the strainer, vst filter, and vst gasket. My pressures did not improve on the test run 960psi at idle and 1005 at WOT. Engine would run strong and climb plast 5700 for about a mile then cut out and the lowrance would say "low fuel pressure". Each time I tried it would idle and accelerate nicely and them cut out. What should I try next? Or is it time to haul it into the dealership?

Thanks

[spider1]

The High pressure pump has some strainers in it that may need to be replaced.
I would connect a pressure gauge to the valve on top of the VST. You can remove the switch cover on the port side of the motor and run a fuel line there to your seat so you can watch the gauge as you run. The pressure should stay at 50 psi (ive or take a few psi) while you run.

[MN Phoenix]

What the mechanics were able to determine is that the fuel line had been eaten away by the ring free and pieces of the line were blocking fuel where it goes into the engine. My boat was rigged with a quicksilver fuel line and I guess it dosen't hold up to the additives. I ran it last night and it seemed to be fine other than the pressure readings were still not any higher.

[rangerguy]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by MN Champion &raquo;</td></tr><tr><td class="quote">What the mechanics were able to determine is that the fuel line had been eaten away by the ring free and pieces of the line were blocking fuel where it goes into the engine. My boat was rigged with a quicksilver fuel line and I guess it dosen't hold up to the additives. I ran it last night and it seemed to be fine other than the pressure readings were still not any higher. </td></tr></table>

I'm betting the ring free didn't do the eating away of your gas line, it was the ethanol gas we have to run now days. Have you been using Marine Stable????

[MN Phoenix]

There is no doubt that ethanol has done some damage.

[toledo freak]

that's what happens when you put mercury parts on a yamaha!!!!!