fuel tank issue

Classic Parker Boat Forum

Help Support Classic Parker Boat Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.


New member
May 29, 2006
Reaction score
HELP!! I'm a charter boat operator here in alaska. I've had my Parker 2530 at the Yamaha shop for 4 months and I thought they had it fixed back in March. I ran it for about 3 or four hours and now it won't go above 2000 rpm. I have a Yamaha 225 two stroke. The mechanics seem to think there may be particulates in the fuel tank. The problem is that when running up on step at about 4500 rpm's the engine drops to say 3500 and may stay there or kick back in. It's got a mind of its own. I'm told as of a couple of days ago that now it won't go above 2000 rpms. I'm not to mechanically inclined, but any valuable information that I can pass on to more competent ones in that area would be greatly appreciated. Thanks.

I have a 2002 225 OX66 than has similar symptom although mine won't run higher than 1800 RPM without bogging down. Just dropped it off at the shop so I'm not sure of the exact cause but I'm pretty certain it is fuel related and most likely a failed low pressure fuel pump(s) as they are original to the motor (250 hrs) and prone to fail.

Check out this link too:

http://www.thehulltruth.com/forums/thre ... 17&posts=6

Good luck.
Betcha its a fuel filter cloggin on the engine. Any qualified Yamaha mechanic should be able to find that.

By chance, does Alaska have Ethanol (10%) fuel?

I had a similar problem with a 1988 Pursuit center console I owned a while back, and the problem was traced to particles floating around in the fuel tank that would clog the outlet line.

I'd eliminate fuel filter-based issues first, then, if that doesn't fix the issue, start looking hard at what's going on in your tank.
This may seam crazy but the exact same thing happened to me last season.
I spent hours and hundreds of dollars trying to fix the problem. I checked the tank, hoses, pump ect. all but the simple things.
Turned out that when I put on the spin on fuel filter/water separator, the o-ring buckled causing a minor air leak. The leak was not large enough to effect low RPM operation, like in the yard, but she wouldn’t run above 3000rpm or would surge the way you are describing.
My advice is to look for air leeks, such as loose hose clamp, split fuel lines or the o-ring on the fuel filter. The o-ring should be lubed with 2 stroke oil prior to installation.
Good luck
Just heard that the issue I was having (bogging down/won't exceed 1900 RPMs) with my 225 OX66 was a clogged filter in the VST tank. Seems to be a common problem and very simple to fix.

How exactly do you fix the clogged filter in the VST tank? Just curious b/c I am having similar problems.
The VST filter is relatively easy to get to and clean.

0) If you are going to access the VST tank, you really should plan on replacing the gasket, so get one from your local dealer to have on hand. You might be able to re-use the other one, but better to have it if you need it.

1) Before you do anything, depressurize the fuel system by wrapping a shop rag around the schrader valve at the top of the VST tank and "deflating" it using a screwdriver or your fingernail like you would deflate a car tire.

2) Drain the fuel out of the VST tank by removing the drain screw at the bottom of the tank. Remember that the VST tank is where the gas gets mixed with the oil, so don't be alarmed if your gas comes out looking funky.

3) Loosen as many of the screws as you can around the top of the tank, I think there are 9 in total, and 3 or 4 may be blocked.

4) There are three mounting bolts that secure the VST tank to the engine block. If I remember correctly there are also two washers per bolt, one on either side of a rubber spacer, so make sure you don't lose these or forget them.

5) Remove all three bolts and the VST tank should come free. You may have to disconnect one of the wiring harnesses to get enough slack so that you can work on the VST tank.

6) Once the tank is free, remove all 9 of the screws in the top of the tank. The bottom of the tank should drop free.

7) At the bottom of the VST pump, there is a round filter that can be un-twisted. It is part #23 in the diagram below. Make sure to take a good look at how it goes together so that you can re-install it. There is a 'catch' on the filter that gets twisted onto a 'post' to secure it. The filter is the bottom-most plastic piece that has a fine mesh surface that can be cleaned off.

8) Hold the filter up to the sun to see if it is really clogged, and clean it with a shop rag. If you live in the northeast, where we no longer have the sun, use a flashlight or alternative light source. Also check to see if there is any visible debris inside the VST tank and clean it out if needed.

9) Re-install the filter by twisting it back in place.

10) Check the condition of the VST tank gasket, replace if necessary, then put into place.

11) Re-install the 9 screws that hold the top of the tank to the base.

12) Re-install the 3 bolts, don't forget the two sets of washers.

13) You can prime the VST tank by squeezing the fuel primer ball to make sure there is some gas present before starting.

For you guys having surging problems, and haven't done any of the routine maintenance on your engine, there are a couple of other potential culprits.

One is the O2 sensor, which should be tested for correct operation using the test harness, and also visually inspected for carbon buildup and cleaned if necessary. The other are the low-pressure fuel pumps. Your engine will have 2 or 3 of these that should be replaced every couple of years. They are relatively inexpensive. And since you've done this much, its not that much more work to properly adjust the TPS and make sure your oil control rod is properly adjusted.

If I can do it, anyone can.

-- Tom


  • VST Tank.gif
    VST Tank.gif
    19.4 KB · Views: 3,771

Since I originally didn't know what the problem was, I took it to a mechanic. TomS described the exact procedure that the shop explained to me. They also said the gasket will need to be replaced anytime you go through this process. Just a heads-up that the gasket is around $30. Good luck.
Adding these pics (from another CP User I believe) to collect info in one post.

-- Tom


  • vst_filter_135.jpg
    176.3 KB · Views: 3,058
  • injector_filter_376.jpg
    77.8 KB · Views: 3,058
Adding pics of engine mounted fuel filter.

-- Tom


  • fuelfilter.gif
    34.9 KB · Views: 2,782
Just make sure you twist the VST filter the right way when you go to remove it. Twist it wrong and you'll break the tabs off....

Don't ask me how I know that. :(
Why would you "clean" injector filters rather than replacing them? Seems the time to remove, clean, and re-install including the chance that it has to be done over, would significantly outweigh the cost of new parts.