Yamaha F250s 2006

offshore

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Went out for the first time last weekend. At 3000 3500 engines running perfect brought it up to 4000-4200 one engine drops to 3000-3200 bogs down. I ran around st 3000-3500 for a while brought it back up same problem. I already had changed the water separate and the fuel filter in the clear plastic housing on the engine as I do every year as part of my maintenance. Both engines feed off the same tank. Any suggestions? Thank you.
 

jaydub

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I have a 2006 Yamaha 250 and had a similar problem last year. It would not accelerate beyond about 3300 rpms. The repair guys hooked it up to a computer and took it out and ran it. Turned out it was a bad cam position sensor. They replaced it and it has been fine since. Not sure if that is the problem you are having but it sounded similar. I had a post in this forum in August 2015 that described the problem and the fix. Here is the info from the post: Acceleration problem
Postby jaydub » Aug Thu 06, 2015 4:22 pm. You can search for it and get to it.
Hope this helps.

Jaydub
 

beachbum

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check VST filters- even if they are gummed up, you can get 2000-3000 rpm but not any higher
 

seasick

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jaydub said:
I have a 2006 Yamaha 250 and had a similar problem last year. It would not accelerate beyond about 3300 rpms. The repair guys hooked it up to a computer and took it out and ran it. Turned out it was a bad cam position sensor. They replaced it and it has been fine since. Not sure if that is the problem you are having but it sounded similar. I had a post in this forum in August 2015 that described the problem and the fix. Here is the info from the post: Acceleration problem
Postby jaydub » Aug Thu 06, 2015 4:22 pm. You can search for it and get to it.
Hope this helps.

Jaydub

In your case, you couldn't go over a certain rpm. In the original post, the motor did rev higher but then dropped off. I don't think you had the same problem The problem to me has all the evidence of a fuel flow issue.That is what I would look into first and the high pressure pump screen is a prime suspect. ICheck the on board canister filter, you can swap the filters between motors and see if the problem changes motors. The same approach goes for fuel lines to a point, primer bulbs etc. I don't like swapping parts like that but sometimes it is better than blindly replacing suspect and expensive parts.
If you have an extra helper, feel the firmness of the two primer bulbs when all seems OK (at speed) and when the problem occurs. If one primer gets softer, you have a restriction between that bulb and the tank. If pumping the bulb makes the motor run faster, you probably have a low pressure pump issue. If both bulbs are firm when the problem occurs, you may have the upstream (towards motor) restriction
 

Doc Stressor

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A bad camshaft positions sensor will throw a code and force the engine into limp mode (2000 rpm). Restarting the engine will often temporarily fix the problem.

The symptoms are typical of a fuel flow issue and the most likely cause is a clogged vapor separator tank (VST) filter (high pressure pump screen that is located in the VST). It's an easy fix that involves cleaning or replacing the filter except for the act of getting to the VST tank. This requires a lot of disassembly.

Check out all of the upstream filters first, since getting at the VST requires a lot of time and effort. If you're not a good do it yourselfer, it's best to have a shop do the work.
 

georgemjr

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There is an "F" fuel filter that is most likely your culprit. Easy to swap out and cheap. It is located behind your intake manifold on the port side of the engine. I had the same issue with my 2006 F250 as did Gman with his 2005. You will need to remove the intake manifold (very easy to do) swap out the filter, which looks like the shape of an F, hence the name, and you should be good to go. It is the cheapest, easiest fix mentioned and would be where I would start, as it resolved my exact same problem and is an often overlooked fuel screen which gets clogged and then the clog dries up over the winter and restricts fuel flow. Good luck, and don't forget to post your results for other members to use as a resource...george
 

offshore

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F Filter the problem. Changed both of them engines running like a top. F filters will be part of my regular maintenance from now on. Thanks for the feed back. Second Nature back in the race. Tight lines. All the best.