03 OX66 200HP bogging prob

[Karljs1]

When I have been WOT for about 4 to 5 minutes my engine will bog/stall. If i catch it quick enough and throttle back it does not stall. 3/4 throttle I am ok, it will run all day.

Through searching this and other forums I beleive it is a fuel problem.

1. My first step is to clean out the VST. I have an engine manual, but it is not more than pictures. not to much actual instruction. Can someone provide a link to a how to on how to remove this. I have searched and cannot find anything.
2. my next step is to clean the o2 sensor. I think I found a good right up for that, but feel free to add others. I probably need to do this anyway.
3. check and replace the LP fuel pumps

If anybody has other suggestions or ideas feel free to add them.

Thanks,
In advance
Karl

[rodbolt17]

without a model number it could be a 2.6L or a 3.1L engine.
procedures vary a bit but not much.
the VST tank can be removed without dissconecting the fuel lines.
loosen all the screws you can get to.
then remove the 3 10mm hex bolts that hold the tank to the block.
then remove the two VST screws you could not get to.
then the tank will drop off.
if you cut the fuel line clip it MUST be replaced with the same oeticker style clip. DO NOT use a standard hose clamp.
while the tank is away from the block you can access the lift pumps.

[Karljs1]

Thanks for the reply, the engine is the 3.1 model. I do not have it here, but I can get the full model# if that would be helpful. Off the top of my head it is a 3.1L VMAX OX66 fuel injected 200 hp.

[Tucker]

You need to search better. Not just here but other owner forums. There are threads complete with pics and step by step procedures. Personally I wouldn't tackle the job without the shop manual. The tank is sealed with an o-ring that can be a little tricky getting back in, might want to order a spare. The filter for the HP fuel pump may also be clogged. Removal and installation may be tricky if you've never done it before.

[rodbolt17]

its not complecated at all.
biggest difference is the design of the tank gasket and the 2.6L had 2 lift pumps, the 3.1l 3 LIFT PUMPS.
its also why model numbers,until 06, are critical.
one would almost think I do this occasionally .
personally, most the you tube procedures for doing things suck at best.
I look at some occasionally and simply shake my head,show my wife, laugh and hope no one gets hurt.

my sisters ex husbands brother in law managed to get a 54 ford tractor running so he must know.

all ya need is an altenator.

[99yam40]

Rod,
You are going to run that one into the ground aren't you

but it is a good one, after watching it I can envision copying the post and inserting it into that system to see what it will look like sometimes while reading some posts

[rodbolt17]

I actually have similar conversations, especially with commercial guys.
and yes I have gotten aggrevated enough to simply pick up my tools and leave the boat.
the 3.1 L vmax, if its in fact a VX200, does not use the CCS system.
its a striaght forward closed loop speed density EFI setup.

[Tucker]

WTF with the alternator?? Yup, be interesting to see rodbolt put the owner under the lights to get the rest of the story. "I was just crusin' and the thing turned to fubar; I didn't do nothin!"
And I do take exception to "it's not compilcated at all" Maybe not if you've done it a 100 times!! I have no sympathy to a guy that messes up because they are too cheap to by a shop manual. How much does it cost to get the VST serviced?

[Karljs1]

Finally got back in town the actual model # is VX200TLRB

Tucker do you have a suggetion on service manual. I did purchase one, but frankly it looks more like a parts diagram that car part places use than anything helpful

[Tucker]

Yep, that's about it Karl. It doesn't tell you how to do anything. But it does describe every part and how they are assembled. Get on thehulltruth and do a search, say..."cleaning VST". Should get tons of info. There's also a very good tutorial about how to clean the 02 sensor. I believe it's called "cleaning the yamaha sniffer". Sorry I don't have any of this anymore. My new (old) boat is carbed with no 02 sensor. Don't despare it's not that hard; just search, do your homework and ask lots of questions. I'm willing to bet a cold beer that the filter on bottom of your HP fuel pump is clogged. Get all of this done, change over to 2-micron on-board fuel filters and you shouldn't have to remove the VSTagain (well not for awhile). I'd also be running ring free & Startron with every tank full. I'm feeling your pain, when I had my OX66 I had the same problem. It is important that you address this ASAP. Sounds like you may be running in a lean condition which may cause your motor to seize.
As far as the LP pumps go, they do have a rather short life span. If they've been in there more than 3-years they should be replaced, they're cheap enough (about $43 each I believe)

[rodbolt17]

DO NOT use a 2 micron filter.
its simply to restrictive.
O2 sensor cleaning is a teat on a boar hog if you dont test the O2 sensor output voltage when done.
yes the 3.1L motors are rather hard on lift pumps.
yes the VST is dirt simple to clean.
the tank can be removed without dissconecting any fuel lines.
if not swelled or damaged the tank oring can normally be reused.
the VST filter can normally be cleaned.
Yamaha reccomends a 10 micron hull mounted fuel water seperator with a 90 gallon per hour flow rate for that engine.
at or near wide open that engine can burn about 22 gallons per hour.

[Tucker]

2-micron Racors flow 60GPH and are being beta tested in New England by some big block owners for about 3-years, I've used them for 2-years; so far no problems but I do carry spares. Racor guys jumping in on the problems ethanol causes when it cleans old fuel tanks (been there). Of course Yami is going to recommend 10-micron filters. The 2-micron screens on the injectors and HP fuel pump will catch anything that get through. Keeps their service division busy, business is business and that is understandable..

[Karljs1]

Do these fuel water seperator filters replace or are they in addition to the one on bolted to the side of the block?

[Karljs1]

BTW, I did finally find a bunch of step by steps posts. Had to go to the Hulltruth. Thanks for the heads up!

[Tucker]

They replace the screw on hull mount filter. The Yami is 11/16" threads, I believe. I'll double check part numbers tonight and report back. Note that this is a 2-piece assy. The bowl is separate and reusable and is a 1-time purchase.