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Yamaha VMax 225 05 - VST Help
#13497825
04/01/20 10:00 PM
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Joined: Mar 2008
Posts: 1,905
westtexgolfer
OP
Extreme Angler
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OP
Extreme Angler
Joined: Mar 2008
Posts: 1,905 |
The motor starts and idles great. The issue is when giving it any throttle it will speed up but does not stay constant. We are thinking about draining the fuel tanks but wanted to get thoughts first. It revs up and down swinging really bad upon increasing the throttle. 2000 to 500 to 2000 and so on. But no issues idling for an extended period. Fuel pump has been replaced. Anything else it could be besides bad fuel causing the issue?
Last edited by westtexgolfer; 04/04/20 03:53 PM.
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Re: Yamaha VMax 225 RPMs Swinging
[Re: westtexgolfer]
#13497955
04/02/20 12:02 AM
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Joined: Aug 2003
Posts: 362
CADD
Angler
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Angler
Joined: Aug 2003
Posts: 362 |
Not know details of the motor, I'm going to say it's your VST filter is clogged
2001 Pathfinder 2200V 150Vmax HDPI 2015 Diablo Amigo (Sand Fleck)
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Re: Yamaha VMax 225 RPMs Swinging
[Re: westtexgolfer]
#13498539
04/02/20 02:49 PM
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Joined: Jul 2010
Posts: 1,349
boatman025
Extreme Angler
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Extreme Angler
Joined: Jul 2010
Posts: 1,349 |
I would say same thing VST filter and I would get Injectors clean also
Hughes Marine 3855 Osage Lane Wylie ,Texas
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Re: Yamaha VMax 225 RPMs Swinging
[Re: westtexgolfer]
#13499730
04/03/20 09:56 AM
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Joined: Mar 2011
Posts: 14,049
Bandit 200 XP
TFF Guru
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TFF Guru
Joined: Mar 2011
Posts: 14,049 |
Don't run it that way, take it a shop. but you know that.
Triton 200 XP 200 Yamaha 0X66
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Re: Yamaha VMax 225 RPMs Swinging
[Re: westtexgolfer]
#13499903
04/03/20 01:17 PM
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Joined: Jul 2010
Posts: 1,349
boatman025
Extreme Angler
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Extreme Angler
Joined: Jul 2010
Posts: 1,349 |
We can check your motor out for you
Hughes Marine 3855 Osage Lane Wylie ,Texas
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Re: Yamaha VMax 225 RPMs Swinging
[Re: westtexgolfer]
#13500271
04/03/20 04:49 PM
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Joined: Mar 2008
Posts: 1,905
westtexgolfer
OP
Extreme Angler
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OP
Extreme Angler
Joined: Mar 2008
Posts: 1,905 |
We are going to look into the O2 sensor and VST filter to see if it resolves the issue. Appreciate the help.
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Re: Yamaha VMax 225 RPMs Swinging
[Re: westtexgolfer]
#13500374
04/03/20 05:54 PM
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Joined: Jul 2010
Posts: 1,349
boatman025
Extreme Angler
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Extreme Angler
Joined: Jul 2010
Posts: 1,349 |
if 02 wets most time cant clean
Hughes Marine 3855 Osage Lane Wylie ,Texas
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Re: Yamaha VMax 225 RPMs Swinging
[Re: westtexgolfer]
#13501655
04/04/20 03:43 PM
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Joined: Mar 2008
Posts: 1,905
westtexgolfer
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Extreme Angler
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OP
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The engine is a 05 yamaha 225 vmax. I do not believe it has an o2 sensor. But the VST filter was extremely dirty a d there was about 1/8" of trash built up in the bottom of the separator tank.
We have ordered new gaskets and filter to replace.
Does anyone know if the fuel o should fall out of the top part? I need a diagram or someone to explain how the fuel pump sits back in the top of the vst. There is a small plastic piece that goes on the discharge of the l u.p that slides up and down. But not sure which way it goes or if there should be an l ring in that piece where the fuel pump discharge tube sits?
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Re: Yamaha VMax 225 RPMs Swinging
[Re: westtexgolfer]
#13502451
04/04/20 11:40 PM
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Joined: Dec 2013
Posts: 459
PlanoPaul
Angler
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Angler
Joined: Dec 2013
Posts: 459 |
Yes it does have an O2 sensor, and they cause lots of problems. I would be looking at the O2 for sure.
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Re: Yamaha VMax 225 RPMs Swinging
[Re: westtexgolfer]
#13504288
04/06/20 02:32 AM
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Joined: Feb 2017
Posts: 390
lurenthewind
Angler
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Angler
Joined: Feb 2017
Posts: 390 |
If the VST had a lot of trash in it, I would clean it and replace the filter there, but I would also replace all the other filters. Your power head could be at stake if you don't. If just one of the injectors goes lean it could destroy the power head.
There are 8 mystery filters, 2 in the High Pressure pumps and one in each of the 6 injectors. They cost less than $1 each and are a PITA to change. There is a filter inside the clear plastic housing that is the initial filter that feeds the VST tank. There is the filter on the bottom of the electric fuel pump inside the VST tank There is a replaceable inline filter that is just above the VST tank that has a tricky little connector on one end and a hose clamp on the other. This also might be a good time to replace the low pressure pumps since there was lots of trash in the VST. They are about $40 each and there are two of them. And if you do not have a water separator in the bilge, add one. If you have one make sure it is replaced at least every year, preferably more often that that.
Most of the HPDI motors do OK if the fuel system is maintained frequently, but can explode in a heartbeat if you don't.
Wayne
Luck will beat skill any time you have enough of it!
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Re: Yamaha VMax 225 RPMs Swinging
[Re: westtexgolfer]
#13508698
04/08/20 06:39 PM
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Joined: Oct 2008
Posts: 215
river oaks
Outdoorsman
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Outdoorsman
Joined: Oct 2008
Posts: 215 |
you wouldn't no how to disconnect that ( tricky little connector ) would you
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Re: Yamaha VMax 225 RPMs Swinging
[Re: westtexgolfer]
#13508767
04/08/20 07:27 PM
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Joined: Dec 2004
Posts: 27,656
Fish Killer
Big Sexy
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Big Sexy
Joined: Dec 2004
Posts: 27,656 |
Gotta push the sleave in as you pull the hose out. I used a box wrench to slide down and compress the sleeve.
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Re: Yamaha VMax 225 RPMs Swinging
[Re: westtexgolfer]
#13509016
04/08/20 10:07 PM
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Joined: Feb 2017
Posts: 390
lurenthewind
Angler
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Angler
Joined: Feb 2017
Posts: 390 |
^This
You HAVE to keep the push sleeve pushed all the way in when you pull the hose out. Kinda a PITA because you are pushing one way and pulling the other at the same time.
Luck will beat skill any time you have enough of it!
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Re: Yamaha VMax 225 RPMs Swinging
[Re: westtexgolfer]
#13516208
04/13/20 07:03 PM
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Joined: Aug 2003
Posts: 362
CADD
Angler
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Angler
Joined: Aug 2003
Posts: 362 |
Search or google HPDI and VST etc and you'll find lots of how-to's with pictures on other forums (the hull truth) is the one I used the most. On the overpriced filter learned this trick and it worked pretty well. Harbor Freight Panel Clip Pliers HF Pliers
2001 Pathfinder 2200V 150Vmax HDPI 2015 Diablo Amigo (Sand Fleck)
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