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2006 yz250f accelerator pump not working

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I picked up a yz250f for a pretty good deal. All that was wrong was a bog off idle. I thought easy fix just need clean the carb and change some jets, not knowing what I was getting myself into aka the infamous bog that all these damn 250fs have. 

My current hypothesis on why it isn't working, the accelerator pump does not seem to be squirting any fuel at all. Today I cleaned the shit out of the acc pump blowing carb cleaner and air through all the passage ways, and leak jet. Both the o rings, and diaphragm are in great condition. Still no squirt. The bike came with a boyeson quick shot, and I'm thinking about upgrading to the quick shot 3 just to get rid of the hassle of changing out leak jets, which I am still not convinced is the problem as the leak jet is stock. I tried the o ring mod but since my acc pump isn't squirting it did absolutely nothing. If anyone has any suggestions or fixes to my problem it would be greatly appreciated. 

Dean

Edited by Dean.b

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I picked up a yz250f for a pretty good deal. All that was wrong was a bog off idle. I thought easy fix just need clean the carb and change up the jetting, not knowing what I was getting myself into aka the infamous bog that all these damn 250fs have. 

My current hypothesis on why it isn't working, the accelerator pump does not seem to be squirting any fuel at all. Today I cleaned the shit out of the acc pump blowing carb cleaner and air through all the passage ways, and leak jet. Both the o rings, and diaphragm are in great condition. Still no squirt. The bike came with a boyeson quick shot, and I'm thinking about upgrading to the quick shot 3 just to get rid of the hassle of changing out leak jets, which I am still not convinced is the problem as the leak jet is stock. I tried the o ring mod but since my acc pump isn't squirting it did absolutely nothing. If anyone has any suggestions or fixes to my problem it would be greatly appreciated. 

Dean

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Sorry, no suggestions or fixes, but I think I'm experiencing the same issue. Went through the carb on my 2008 wr250f and cleaned everything. I think the bog is worse now. When I roll the throttle slow, no problems. But when i crank it fast, it bogs down and kills the engine (works great as a kill switch, since my actual kill switch was broken (replaced that last night)).

Gonna try and remove just the bottom part of carb (so we don't have to remove the whole thing) and check out the accelerator pump. Is that boyeson quick shot 3 worth it for $120?

 

 

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Sorry, no suggestions or fixes, but I think I'm experiencing the same issue. Went through the carb on my 2008 wr250f and cleaned everything. I think the bog is worse now. When I roll the throttle slow, no problems. But when i crank it fast, it bogs down and kills the engine (works great as a kill switch, since my actual kill switch was broken (replaced that last night)).
Gonna try and remove just the bottom part of carb (so we don't have to remove the whole thing) and check out the accelerator pump. Is that boyeson quick shot 3 worth it for $120?
 
 

I'm experiencing the same issues. I'll post a video later today. I personally don't have the quick shot 3 so I don't know if it's worth it or not.

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Confirm the passage way from the AP to the nozzle is clear. Confirm the diaphragm is not in upside down and the spring is in correctly.
DO NOT turn  the adjusting screw unless you have the skills to reset it. Get a service manual.

I was able to spray carb cleaner and air all the way through to the nozzle and then the leak jet. Still no squirt when I put the tank back on and get some fuel running through it. At first I thought the previous owner might have tinkered with it and put in a leak jet that is to big but it seems to be the stock size. Sorry for cross posting I'm new to the app and accidentally posted it on the wrong forum.

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Stock leak jet (IIRC, a #70)will squirt, just not a lot.

Either the diaphragm is bad, the adjustment of the screw off (the manual covers setting it to stock, a PITA) or the check valve is not working (causing all pressure to back flow).

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Stock leak jet (IIRC, a #70)will squirt, just not a lot.
Either the diaphragm is bad, the adjustment of the screw off (the manual covers setting it to stock, a PITA) or the check valve is not working (causing all pressure to back flow).

Where would the check valve be located

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Base of the float bowl.
It consists of a square brass plug, a tiny spring and ball.

What should I look for when disassembling the check valve?

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check-valve-removed.jpgwhere-is-the-check-valve.jpg

Sorry I wasn't very clear. What would be some signs that I need to replace it? Does it need to be cleaned? Etc

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Just now, Dean.b said:


Sorry I wasn't very clear. What would be some signs that I need to replace it? Does it need to be cleaned? Etc

Cleaned and checked to ensure it works (it is a one way valve).

The AP is nothing more than a finely adjustable squirt gun.

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Cleaned and checked to ensure it works (it is a one way valve).
The AP is nothing more than a finely adjustable squirt gun.

Thanks this is very much appreciated as I am going to Winchester bay tomorrow and want my bike to be running at its best. Let's say that cleaning the check valve doesn't fix the problem. Should I rebuild the accelerator pump? Where would I get a complete rebuild kit since I haven't seen them Rocky Mountain or motorcycle superstore.

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10 minutes ago, Dean.b said:


Thanks this is very much appreciated as I am going to Winchester bay tomorrow and want my bike to be running at its best. Let's say that cleaning the check valve doesn't fix the problem. Should I rebuild the accelerator pump? Where would I get a complete rebuild kit since I haven't seen them Rocky Mountain or motorcycle superstore.

The only actual 'wear item' is the diaphragm. If when the throttle is opened very fast, the AP arm presses down on the diaphragm, the fuel in the chamber is supposed to go up and out the nozzle, very simply system that has the ability to be adjusted (or mis-adjusted as to not work at all)

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The only actual 'wear item' is the diaphragm. If when the throttle is opened very fast, the AP arm presses down on the diaphragm, the fuel in the chamber is supposed to go up and out the nozzle, very simply system that has the ability to be adjusted (or mis-adjusted as to not work at all)

Would you recommend that I replace the diaphragm

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2 minutes ago, Dean.b said:


Would you recommend that I replace the diaphragm

If it is stiff or possibly not pressurizing, then yes. If it is original to the bike, I am sure it is shot.

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If it is stiff or possibly not pressurizing, then yes. If it is original to the bike, I am sure it is shot.

Ok I will be sure to order a new one soon. So let's say I need to change my leak jet should I invest in the boyesen quick shot 3 or just buy an assortment of jets.

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