Yamaha 250hp 2 Cycle - Bogging Down? - Page 2

bbh57 · #11 06-27-2010, 05:04 PM

I just worked thru a problem on my 98 carbed yamaha 200. It needed constant bumps on the choke to idle and it would bog down while running and again using the choke I could get it to preform for a short distance then id need to pump it again. I pulled the carbs cleaned them no help. ran a seperate tank nothing, I also took apart one of the fuel pumps it looked fine. finialy I decided to de-carb(I have not ever done this to this motor.) using sea foam. It did the trick. although the seafoam may have cleaned somthing I missed besides the carbon, Its running great now.

Here is the seafoam de-carb procedure I used.

Also Yamaha wanted 53.00 each for new bowl gaskets!

http://www.switchbait.com/forums/showthread.php?t=159

jeff6645 · #12 06-27-2010, 10:42 PM

Thanks bbh57, I will give it a try.

I have read about using Seafoam to decarb but was never really sold on the idea. I read were they talk about it smoking while doing the decarb and thought it was just the Seafoam burring off... but after reading this procedure where it stops smoking after 2 or 3 times I am more convinced.

Thanks again for the link, I will let you know how it goes.

bilgerat · #13 06-28-2010, 10:41 PM

Ive read something about 02 sensors on a yamaha clogging up with carbon and causing surging, loss of power and excessive smoke, might check into that

jeff6645 · #14 07-03-2010, 11:24 PM

Tried the Seafoam decarb mixture...

Mixed 3/4 gal gas, 1 can of Seafoam and 3oz of two cycle oil.

Removed the line going to the primer bulb and gave it a few pumps started the motor and let idle for 15 minutes. About 5 Min's in it started to smoke like it was on fire. Cut motor off after 15 Min's and let set for 15 Min's... discovered that in 15 Min's of idling the motor used almost the whole gallon of fuel... only about 6 oz left.

Restarted the motor after 15 mins and it smoked like crazy!!! Ran better, but still not back to normal.

By doing this test I may have discovered the problem. 1 gallon of fuel in 15 Min's while idling seems really high so I think it's a choke or fuel pump issue...

PS: on the way home today broke an axle, had to rig up a brace to get back to the boat ramp to launch the boat so I could take the trailer about 20 miles to get it welded

So new axles will be required ASAP...

Bushwacker · #15 07-04-2010, 01:01 AM

My old carbed 115 V-4 burned 2 gal/hr at idle, and a V-6 would burn even more, so the fuel you used sounds about right!

76Red18 · #16 07-04-2010, 09:51 AM

I think mine burns more at idle than at wot!!

Use that seafoam a couple more times. Let it sit a while longer also. The seafoam acts as a solvent to "dissolve" the carbon in the cylinders and the crud in the carbs.

jeff6645 · #17 07-04-2010, 07:56 PM

Thanks Guys! I feel better now about the fuel usage. Me and the boy love to go WOT, but the women wants to idle everywhere we go, now I have an excuse to go faster... I am saving fuel!!!

I will try the seafoam treatment again. The primer pump bulb is sucking shut again, so got to do some more investgating.... I may name the boat "Something Else" cause here lately it's always something esle... but still love here.

Bushwacker · #18 07-05-2010, 01:14 AM

Quote:

. . The primer pump bulb is sucking shut again, so got to do some more investgating....

That means there is a flow restriction UPSTREAM of the primer bulb, like a plugged filter, plugged screen on fuel pickup in the tank, plugged elbow, etc. Sounds like maybe the "ethanol-fuel-cleaning-out-tank disease!

Islandtrader · #19 07-05-2010, 09:51 AM

Quote:

. . The primer pump bulb is sucking shut again, so got to do some more investgating....

That means there is a flow restriction UPSTREAM of the primer bulb, like a plugged filter, plugged screen on fuel pickup in the tank, plugged elbow, etc. Sounds like maybe the "ethanol-fuel-cleaning-out-tank disease!

Check the anti siphon valve on the tank. You can remove it and change it or just leave it off.

jeff6645 · #20 07-17-2010, 12:49 AM

Replaced the primer bulb and solved the collapsing problem. The old one was very soft and had no resistant.

Ran another can of Seafoam throught it. Pulled carbs and cleaned and put in another new set of plugs.

But still not running right, when I go to WOT it will only run about 2000RPM for about 3-10 minutes before taking off. But still not getting the old top speed of 47mph, top speed now is 42 in ideal conditions.

Anyone know a good trustworthy Yamaha or outboard tech in the Mobile, Al. area?