Help with HPDI dropping RPM’s at holeshot

[MichAngler]

First this is a 2005 VZ250TLR 250 HPDI
Well maintained and no major issues from day one

This started 2 weeks ago

When I punch it to jump on plane as the power/RPM’s rises it starts to flutter like I’m jumping on and off the throttle

Now I also noticed it started running rough at idle so I replaced the primer bulb and that fixed the rough idle but not this issue
I also has replaced the plugs two weeks prior so I replaced them again – still no help

I can “creep” the throttle forward real slow and it does not do this but makes for a very long holeshot
I can slow way down and punch it and it doesn’t do this the only time is during the holeshot
Motor runs great on plane at any speed without any issues

Only thing I have been doing different is with the price of gas I have been running at 40mph most of the time to save gas but can go WOT with no issues

I have a link below to a short video with sound so you can see what I’m talking about
NOTE I went just enough to show the problem not getting fully on plane
(was afraid of losing my phone holding it and the wheel with one hand at the same time)

Any and all help would be appreciated

http//www.royrandolph.com/images/FullSizeRender.MOV

[21XDC]

Fuel, spark or air.... I doubt that it's spark or air. Looks and sounds like a fuel starvation. Have you cleaned all of the filters and hidden filters?

[MoBob]

I would bet you have an issue with the low pressure lift pumps. I had a similar issue with my last yami. Not identical but very similar.

[MichAngler]

From what I can tell this series doesn’t have the hidden filters
At least they don’t show up on the parts diagram

I did the standard fuel filter at the start of last season but since I’m going to be in there anyways might as well change that too
First thing I did when I got the boat was add a Yamaha 10 micron filter/separator to the fuel line and I just changed that at the start of this season

And now that I think about it 10 years ago under a Yamaha recall the High pressure pump was replaced
And the symptom for this was similar but at “WOT only” - it would drop a few hundred rpm and you had to kick the throttle to get it to jump back up
So it wouldn’t be much of a leap to say the low pressure pumps are the issue this time
Especially since I watched a few videos today that say the diaphragm should be replace every few years and these have never been replaced

Looks simple enough to replace and the entire pump assembly isn’t that expensive so I’m happy to do it

Thanks!

[mrdeath]

The hidden or 'mystery' filters are called that because they're not on any parts diagram. There's 1 in each of the injectors and 4 in the high pressure pumps. They're cheap and relatively easy to replace. Here's a link to how to replace them. You can find them at many different places. Just google 'HPDI mystery filters'.

http://www.bbcboards.net/showthread.php?t=252124

[MichAngler]

The hidden or 'mystery' filters are called that because they're not on any parts diagram. There's 1 in each of the injectors and 4 in the high pressure pumps. They're cheap and relatively easy to replace. Here's a link to how to replace them. You can find them at many different places. Just google 'HPDI mystery filters'.

http://www.bbcboards.net/showthread.php?t=252124

OK I’ve watched a couple videos on this subject today but the strange thing is no one mentions a Yamaha part number for the new filters or how to obtain them

I see in your link Rich mentions Brucato and Hydrotec I visited both sites and couldn’t find them

Does Yamaha not sell these filters?

[MichAngler]

So I found a set of 8 from star marine but some videos say there are a total of 9 or 10 filters between the injectors and high pressure pump so I ordered 2 sets just in case

Defiantly more than I wanted to deal with but nothing that seems to difficult

I also found a video on youtube that show a motor with an issue that is like mine but a little more extreme and they blame these filters for it so I guess I’m doing this

[MCIPinkie]

I can tell you this from my experience running various HPDI's from 2002 until 2020.

They are very plug sensitive. First thing I learned to do, no matter what the problem, was change plugs.

I was going through 3 sets a year in my old motor, but every time I put new plugs in it, it ran like a scalded dog.

Got to where I carried 6 in the boat.

[MichAngler]

That’s odd because I could go 2 seasons on the same plugs

But I always replaced them right after I burn the winter gas out of the tanks each season

And as I stated I put another set of new plugs in just in case and still no change

Note: the only time I had issues with a new set of plugs was when I bought them off amazon and found out they were Chinese knock offs

[MichAngler]

Ok so I finally got out today to test the new low pressure fuel pumps
First it started right up and purred like a kitten smoother than it has in many years
Pop it in gear and no hesitation or sputtering

Go for the HoleShot and it is now worse than it was before

Prior it would drop 500 rpms and climb back up now it’s like it loses all power for a half a second and then start to climb again and does this 8 or 9 times before it can get up on plane (I can still creep the throttle to avoid this) but make for a long holeshot

SO I guess I’m going to do the Mistry Filters next

Here is the big question
WHAT SIZE FILTER

The three videos that show a good image of the filter each shows a different style and none of the motors are my year and model

Then I find this where they have 12 different sizes/style
https://www.amazon.com/HiSport-Injec...882450&sr=8-23

Can anyone tell me what size/style I will need for my 2005 VZ250TLR
I would hate to pull this apart and find I don’t have the correct filters and have to wait with the motor all tore down

PLEASE HELP

[Oprod]

Sounds like a fuel problem. These engines are very fuel sensitive. I too think it’s the fuel filters/ mystery filters. Or fuel bulb issue, kinked fuel line, collapsing fuel line on wot.

[Chris225]

May want to drop the lower unit and see if the tuner is still fully in place. Let us know what you end up finding.

[MichAngler]

May want to drop the lower unit and see if the tuner is still fully in place. Let us know what you end up finding.

Lower Unit Tuner?
Can I get a little clarification please?
I’ve never seen nor heard of such a thing and the parts breakdown has nothing labeled tuner in the lower unit

[21XDC]

The tuner is the exhaust manifold/header that dumps into the LU. I have a high performance tuner on mine.

[Chris225]

Lower Unit Tuner?
Can I get a little clarification please?
I’ve never seen nor heard of such a thing and the parts breakdown has nothing labeled tuner in the lower unit

The tuners are known to basically melt. Mine did this before. When you go to get on plane the engine dips down further in the water allowing water to get in the crankcase.

[MichAngler]

The tuners are known to basically melt. Mine did this before. When you go to get on plane the engine dips down further in the water allowing water to get in the crankcase.

Yep I got an education on the tuner

But if this was the case I wouldn’t be able to creep the throttle forward making for a very long holeshot at that angle yet it doesn’t have the issue

Also others say I would see issues at other speeds especially at WOT yet it only happens during holeshote

I’m not saying there’s no way it could be this but the odds are its more likely something else

I spent some time on the phone today with the great folks at Hydro Tech and they have some things I need to check and watch for the next time out

I will report back

[Chris225]

Any luck with the repair yet?

[MichAngler]

Any luck with the repair yet?

I have gotten so many opinions on what this could be I can’t afford replacing all these parts just guessing

So I made an appointment at local marina to have them plug it in and see if it’s kicking any fault codes to help me narrow this down
(Just dropped it off today)

Now if it’s simple and they can do it quickly I’ve told them to do it
But if they need to order parts or can’t deal with it right away I’ll take the boat and fish with it until either they or I can deal with it

I have been fishing with it this way for a month now and have become adept at avoiding the issue – it makes for a long hole shot but hey I still get to fish and do tournaments

Note: I’ve noticed that this happens exactly at 3000 RPMs every time and only when the boat is under full load of the holeshot
I can run it up to 2800 rpms and let it crawl out of the hole shot and as soon as the boat starts to level out it goes right past the 3000 rpms with no issue
I also have a low idle (in gear) 500 and should be 800 and I have 5300 at WOT and should go to 5800 so I’m still convinced it’s a fuel problem but may involve a sensor since it only happens at exactly 3000 rpms

I will report back once I hear something

[MichAngler]

Update

The marina printed out a copy of the code list and of course nothing current
It showed a low fuel pressure a month ago and that went away when I replaced the low pressure fuel pumps but right now no current fault codes
They did not take the boat for a test drive and could only rev it up to 2500 rpm’s so considering the issue happens at 3000 they didn’t see anything

The mechanic did tell me the following
First this is a fuel issue
Second the only time he has seen the mystery filters plugged up is when the fuel system gets a lot of water in it and he said he drain the VST tank and there wasn’t a drop of water
Next he said 90% of the time an issue like this is caused by the strainer/filter above the VST tank part number 60V-24251-01-00

He offered to replace it but sense I already had a new one ready to go in I declined
Tonight I replaced the strainer/filter as well as the mid rang filter in the VST tank
The inside of the VST tank looks pristine with zero debris or junk in it

So I’m hoping to get out this Sunday to test but weather may prohibit that

I’m running out of things to replace all that’s left is the mystery filters, mid-range pump at $800 and the two high pressure pumps at way too much to even think of at this time

Fingers crossed

[dricha21]

This spring I had fuel issues. It would get up on plane and run for a while then shut down. It came to a head on a trip to st. claire. We ended up finding tears in 2 of the 3 low pressure pumps diaphrams. It fixed it after finding the diaphrams and changing them. 6 weeks later started having the same problem. I replaced the 3 fuel pumps with yamaha oem fuel pumps and I replaced the hi pressure fuel pump in the vst tank. No help. It ended up being blockage in my needle valve in the intake to the vst tank. Easy fix after a lot of grief.