2 stroke engine sneeze?

Engine runs fine when it warms up however when I first start it up it I have the problem. It will usually stalls at least once then it will run fine. If I have the engine turned off for an hour or so same thing all over, Any ideas?
I changed the plugs, both the fuel line and engine gas filters. I changed the vst filter and snugged up the bolts for the fuel pumps in case of an air leak. My bulb on the gas line is very soft but it has always been that way since I owned the boat.

Engine: 2001 OX66 225

Lean sneeze means your carbs need to be adjusted. Most likely 1 or 2 are too lean, meaning the idle/pilot screw is a 1/4-turn or more too far in. OBs can "change" over time, so this is nothing to be worried about.

Do so ONLY in the water, and NEVER on muffs! Best done floating free (if you can) and not tied up. Try for calm, clear waters without other boat traffic to be worried about.

1) Start it up and get her good & warm.

2) COUNT # of turns to turn carb #1 idle or pilot (Yam term) screw IN all the way until it stops. Your motor might stall ... do NOT lose your count :shock: !

3) Write the count down for that carb! And write down which one as facing OB, like top right as YOU are facing it (note, usually on OBs that carb [if a staggered arrangement] feeds the opposite side cylinder ...)

4) Count back out same # of turns, then tune #1 carb @ idle so you reach highest revs and back off opposite direction 1/8 to 1/4 turn. So if you had to turn IN to get higher, turn it in then back off a tad. Likewise, if you needed to back it OUT to go higher, turn to highest revs then back in a tad.

5) Repeat steps 2 thru 4 for each carb, especially #3!

6) Take for run and cruise, go up to close to WOT, slowly back off and go to headway/idle speed, just in forward, then right to idle in neutral. She should not stumble or cough. If she does, repeat for ALL carbs. You must do these in sequence and all carbs, never 1 carb alone, as they act as a set.

I'm fuel injected. Are there still adjustment screws?

Click to expand...

No idea, but I know many who needed F225 injectors cleaned, but usually wouldn't run well @ throttle speeds ...

I have the same motor, only a 1999 model year.
I struggled with this same problem about 2 years ago.
I know how much of a PITA it is, especially when trying to manuever around
in tight quarters and she sneezes/stalls. :shock:
It was in the fall also, but the weather got cold and I just lived with it until the next season. Before spring launch I ran through most, if not all of the required maintenance items and the problem went away. Because I was unable to run it after each item was serviced (they were done while the boat was on blocks), I do not know which item fixed it but here you go......

Do you have the service manual? I picked up mine from Andy over at SIM. I also bought the Clymer version and to tell you the truth, I like that one better but I reference both as I have found a few discrepencies. The Clymer has photos and step by step instructions, whereas the Yam manual just has diagrams, no "real" instructions....
Some of what is below I'm sure had nothing to do with the problem, but I'll include them anyway just for reference........by no means am I a "mechanic", but these are pretty easy to do for the average DIY'er......

(1) Change that filter under the cowling, the one with the little red ring floating in the bottom.

(2) Your engine has 3 low pressure fuel pumps, sometimes referred to as lift pumps, or lp pumps. All 3 should be changed every 2-3 years as ethanol eats up the plastic diaphrams in them. They are not that expensive and easy to change. Best to follow Yams recommendation on 2-3 years than to try and stretch an extra year or 2 and have 1 fail at the worst possible time. Two of the three are easy to access, the third is behind the vst tank which has to be removed but that will bring us to step 3.

(3) Clean or replace the vst filter, some people clean them, some replace, they are very pricey so that's your call. Have a new vst tank gasket with you, sometimes they are unable to be reused (though I have done it). They are also TOUGH to get back on....patience.....Also, attached to the back of the vst tank is the fuel pressure regulator which also has a filter on it. Since the tank is off, it's a good time to check that filter also.

(4) Clean, clean clean that O2 sensor, mine was gunked up big time. Careful to follow the instructions about sumberging only up to the threads (but not including). There is also a barbell looking draw tube which always needs a good cleaning, the housing holding the sensor has some small passages also. Soak the barbell and sensor mount in some seafoam for awhile, make sure they are clean before you re-install. The gasket for the O2 sensor cannot be re-used, make sure you have a replacement with you.

(5) Check your plugs and if in doubt, change them and also test the spark plugs caps for resistance. Instructions are in the manual, it's real easy. 2 of my 6 were way out of spec so I replaced all of them.

(6) Do a synch and link then check/adjust the throttle position sensor (aka TPS). Also found mine way out of spec.

(7) Lastly, once I splashed I gave it a good dose of Dunk's seafoam de-carb method. This probably should have been done first because it will sometimes gunk up the plugs and O2 sensor with more carbon that loosens up, but I did it backwards since the boat was on blocks and I wanted to get main items complete before I splashed.

(8) T-stats, every year or 2.

(9) If they have never been pulled, I'd check the thermo switches and thermo sensor (mine was pretty rusted).

#'s 8 and 9 above are probably the easiest in the above list.

All of the above are pretty much required maint on that motor. Mine hasn't sneezed since and runs real strong. I run a de-carb every 50 hours now and run through this check list annually, or every 2-3 years depending on what's recommended. I know it sounds like alot, but much of what you see above had never been done to mine. NOw I follow it religiously.

I'm sure there must be something I'm forgetting, so if I remember anything else, I'll edit it.

EDIT: If I had to guess, I'd bet mine was either excessive carbon built up after 10 years (although I do run ring free)

Or..............Since the problem only occurred when the engine was cold and warming up, a problem with the thermo switches or sensor.

Awesome write-up Tim! 8)

Thanks, hope it's helpful.

... by God, I'm so "old school"

Tim,
Thanks for the information, you and the rest of the guys have been very helpful with keeping my motor running strong over the years. I owe everything I know to Classic Parker members and saved tons of money doing the maintenance myself. I'm on basically the same schedule as you with the execption of the O2 sensor. I have yet to tackle a good cleaning and every time I think about it and attempt to find it, I can't locate the damn thing. If you have a picture of where it is on the motor it would be a big help.
I'm due to change out the low pressure fuel pumps in the spring along with the stats and waterpump (3 years). I suspect that the fuel pumps may be the problem after reading your post. The spring of 09 I had the same problem before launch while sitting in the driveway. Like you, I started to change everthing out and it ran fine. I never stopped and started the motor after each part I replaced so I'm not exactly sure what corrected the problem. I did not change out the fuel pumps then, but remember snugging up the screws thinking that an air leak may have been the problem. Currently, I think I can get away with holding off on finding the problem til spring because the motor runs good after it warms up and have no issues when under way. I'm basically staying along the shore striper fishing for the rest of the season. What it did do was prevent me from going offshore for some good tuna fishing in August. I'm sure hoping it is the fuel pumps or the 02 sensor because like you stated it is a real pain in tight spots with other boats around when it stalls.
I too have to clean or replace my VST filter ever 8 weeks or so, do you have to do the same thing? I always use Startron and Yamaha ringfree at fill-up and can't understand why I have that problem. A friend of mine has the same parker with the 200 HPDI (2001) and he has never changed out the VST or fuel pumps yet. 1800 hours on the motor by the way....
Thanks again,
George

Hi George,

I don't have a photo of it actually on the motor but here is a photo of the sensor itself.
If you are standing in front of the motor looking out the stern, it's on your left, toward the top/rear of the motor I believe. I'll be down at my boat on Saturday and will bring a camera. I'll also take photos of the thermo switches and sensor. When I posted this problem a couple of years ago on boats.net, those were the two things they told me to look at which is why I swapped them out. They weren't real expensive and took literally minutes. The thermo switches are what you actually remove when you take the cover off of the t-stat, that's the thermo switch. The other end of those wires are actually just a plug. The thermo sensor looks like nothing more than a 1/2"+- nut with wires attached to it located right next to one of the t-stats. It will probably have some rust on it where the wires are attached to the nut. The other end of those wires is again, just a plug. Very easy to change.

I change my vst filter every year before I splash it. I'm not sure why I have never had one clog up on me during the season, some people have hundreds of hours with no problem, some people clog then constantly.

Here is the pic of the O2 sensor.....I have step by step instructions I could get to you that I used the first time I did it. I forget where I found it on-line, but I saved it. I just have to find them.

George,

Here are the instructions I found on my old hard drive, I forget which website I got it off of..... I have done it without using an O2 socket or a torque wrench, although those do make it alittle easier.....


You will need a few things.
1. A new Gasket set
2. A can of Yamaha Combustion Chamber Cleaner.
3. A Oxygen sensor socket 22mm or 7/8" they measure the same. I got mine at Harbor Freight Tools for $9.00. It is a special socket with a groove cut in the side to allow the wires to exit the side of the socket while removing the sensor.
4. A 10mm socket and socket wrench.
5. A torque wrench.
6. About 6 wire ties.
7. stiff tooth brush.

1. First cut the wire ties off the bundled wires that are holding the 4 wires from the oxygen sensor.

2.Now cut the wire tie that is holding the rubber boot and wires on top of the oxygen sensor housing. You can now slide the rubber boot up the wires off of the oxygen sensor housing.

3. Unclip the two wire connectors that are attached to the 4 wires on the Oxygen Sensor leads.

4. Remove the two 10mm bolts that hold the Oxygen Sensor cover in place. Now carefully lift up on the cover and remove it off of the Oxygen Sensor. The area where the rubber boot was has a slot in the back so it can be removed from the sensor wires. Be careful and gentle not to damage the wires or sensor.

5. Take the Oxygen Sensor socket and carefully place it on the nut that loosens the sensor. Make sure you push the wire shield down toward the sensor. This will protect the wires from damage while loosening the sensor. Now loosen the sensor but do not remove it. The sensor is torqued to 35lbs so it will be tight. You must loosen the sensor before removing the bronze sensor mount.!!!

6. Now remove the three 10mm bolts from the bronze housing. You can now remove the bronze housing and then remove the Oxygen sensor. Set them on a clean towel.

7. If you look at where the bronze housing was on the motor block, you will see a little round tube looking thing sticking out about 1/4 of a inch. This is the sniffer tube. Gently but firmly wiggle and pull on the sniffer tube until it comes out it is one piece. There will probably be some carbon and maybe a trace or oil on the sniffer tube.

8. spray about 1" of the Combustion Chamber Cleaner into a clear glass (Not a plastic cup!!!)so you can see the liquid. Put the perforated part of the sensor in the liquid to soak. (DO NOT SUBMERGE THE SENSOR PAST THE PERFORATED BOTTOM PORTION THE THREADS SHOULD NOT BE IN THE CLEANER.) While this is soaking you can clean the bronze housing and sniffer tube by gently scraping scrubbing brushing and soaking these in another glass with cleaner. There will be some hard carbon buildup on these parts so try to get most of it off. Inside the bronze housing I used a cloth towel with cleaner wrapped around a philips head screw driver to clean out all the recessed areas and it worked well. Make sure the hole in the sniffer tube is clear of debris.

9. After the bronze housing and sniffer tube are clean dry them off with a clean towel and set them aside for now. Now take the sensor out of the cleaner and gently brush the sensor with a tooth brush there should not be much build up on the sensor itself. Most of the build up will be in the housing and the sniffer tube. Now gently dry the sensor with a towel and a little compressed air if you have a compressor. If not just let it air dry for about 45 minutes.

10. Now remove the old gaskets off the motor and look where you removed the sniffer tube. You might have to do some cleaning in the hole where it came out of. Just use a clean towel and a little cleaner and it will come clean. I used a single edge box cutter blade to remove all the gasket material that was left on the motor block.

Now you are ready to reassemble!!

1. Place the cleaned sniffer tube back into its cleaned home in the motor block so you do not forget it.

2. Screw the cleaned Oxygen Sensor finger tight into the clean sensor housing.

3. Place the large gasket for the plastic housing in place making sure the hole lines up with the bolt hole. it is a sticky gasket and will adhere to the motor block.

4. Insert the three bolts into the bronze sensor housing and place the small gasket on the bottom two bolts in the correct direction. Now line up the sensor bolts with the holes and finger tighten the bolts. I first tightened the bolts to 3.5 lbs first then retightened them each a little at a time until the specified 10lbs of torque was reached.

5. Now carefully place the Oxygen Sensor socket onto the Oxygen Sensor being careful not to damage the sensor or wires. Now torque the sensor to the specified 35lbs.

6. Carefully slide the plastic housing over the wires and back into position over the Oxygen Sensor and housing. Be careful not to damage the wires or cover gasket.

7. Place the two cover bolts in the holes and tighten them to the specified 6.5 lbs of torque.

8. Slide the rubber boot back over the top of the plastic cover and put a wire tie to hold the wires and rubber cap in place.

9. Re-connect the two wire connectors and re bundle the wires with wire ties.

Hi Tim,

Thanks for the information. Very detailed and should make it an easy job! I owe you one...

George

No problem, you'll use the instructions once or twice, but after that, you'll do it without even thinking about it. :mrgreen:

George, here are some photos.....

I was able to get the thermo switch and sensor in the one shot together.
The thermo switch has the orange colored heat shield on the wire..it's inside of the cover for the t-stat. Easy to disassemble...The other end of that wire is simply a plug.
The thermo sensor is located in the lower left corner of the same photo. Small, round and just unsrews from the top of the block. Follow that wire down to the other end which is just a plug.

Second photo is the O2 sensor.