Yamaha 225 VMax engine trouble

"I have a 2001 Skeeter 250 zx

"I have a 2001 Skeeter 250 zx with a 225 Yamaha V-Max on the back. The Yamaha is a fuel injected engine I think it says OX66 on the side. I have had it since new and maintain it very well. Before when I would start the engine it would start right up and "idle". Recently I started having trouble with it staying running ( at start up). What I mean is that when I go to crank it over it "catches" and starts but then dies( like its not getting enough gas). I now have to do this starting up several times before it stays on and idles. Once it starts it has a hard time "idling" until it runs for a bit. After that the engine runs fine, although it does hesitate a bit when first engaged. Runs great at top end and slower. Thought it was a fuel problem so I have gone though the tanks twice, thought it was the bulb but the bulb pumps up and hardens as you pump. It does soften up after a while. New fuel filter and plugs, had it serviced as well. Ran fine with new plugs for a day but then went back to the same. Had the O2 sensor cleaned and it helped for about three start ups where the engine started right up and ran fine. Do O2 sensors go bad and can I replace it fairly easy? Could it be a fuel pump problem and if so where is it located, usually? Any help/suggestions appreciated. Sorry for the lengthy post but getting frustrated having to crank the engine over and over before it starts. Dan"

"i have the exacr same engine.

"i have the exacr same engine. ir did the exact same thing. so i did the exact same thing you did. and the answer to all your problems lies in the vst, the big silver tank on the side of the engine. there is a screen filter inside that tank. replace it and it will run like a brand new engine."

"i have the exacr same engine.

"i have the exacr same engine. ir did the exact same thing. so i did the exact same thing you did. and the answer to all your problems lies in the vst, the big silver tank on the side of the engine. there is a screen filter inside that tank. replace it and it will run like a brand new engine."

"Still having problems startin

"Still having problems starting my Yamaha 225 OX66. Hesitates on startup. Have to crank it over 5 or 6 times before it will start and when it starts it has a hard time idling. I have a feeling it is a fuel issue but don't know what it could be. Once it runs a bit (1-2 min) it will idle/run OK. No problem once engaged and no problem running top end. It does hesitate when engaded, as if it wants to stall. Putting new plugs in it again( plugs in it are less than a year old) and wanting to use some of that seafoam to see if it might be a fuel problem. Had engine decarbed/ tunned up in nov 08 so just not sure what the problem is. Looked at the fuel pump filter in evap chamber and it was clean, no junk there, fuel filter clean just trying other stuff and see if it fixes the problem. When I put the new plugs in in Nov 08 it started right up but slowly it went back to this issue at start up. Never had this problem before, bought boat new in 2001( skeeter zx250). Also adujted throttle cable and idles at around 820rpm. Sorry for the long post but any help appreciated.D"

"check the o2 sensor. mine had

"check the o2 sensor. mine had problems with that as well. make sure you replace the gaskets after removing it. there is a little black barrel in the block once you pull the sensor off, make sure it is clear as well"

I took the boat to get the sea

I took the boat to get the seals in the steering cylinder re-done and had the steering flushed. They cleaned the o2 sensor at that time. Do these sensors go out? and if so how do I change them. I've done it many years ago for an automobile but don't have a clue where the o2 sensor is on that engine. Thanks big fish.

Update- Took the O2 sensor out

Update- Took the O2 sensor out and cleaned the "manifold" where the sensor sits. There was some oil residue in there. Took the black barrel out and cleaned the tube out. Residual oil in there as well. The black barrel had a ton of baked on carbon on it so I "scraped" it off and polished the barrel clean. Put it back together and tested it by putting the lower unit in a big tub of water. It starts right up doesn't smoke as much so hopefully this fixes it. I'll let you know.I'm going to run it on the lake this weekend.

"Update: It is fixed!!!!! I bo

"Update: It is fixed!!!!! I bought new mechanical pumps and replaced the old ones. 2 were leaking. It runs like new and smokes much less. Fuel consumption has gone way down. Thanks for all the input. "

Re: "Update: It is fixed!!!!! I bo

I have the exact same boat, engine, and problem. Could someone explain the procedure for replacing the mechanical pumps and part #'s.
Also the procedure for cleaning the VST tank. I see an air pressure fitting on a line above this tank. Is the tank pressurized? It has a brass plug on the bottom of the tank. Is this where the screen is? Any help would be greatly appreciated.
Thank you

FurFish can you pump your fuel primer ball up firm ? If not you probably have at least one (out of 3) fuel pumps bad. If your primer ball pumps up firm your mechanical fuel pumps are most likely fine. However, if you feel compelled to change them out the part number is 6E5-24410-10-00 ( http://www.boats.net/parts/search/Yamaha/Outboard/2001/VX225TLRZ/FUEL/parts.html ), and they're about $40 apiece, there are three of them mounted on the port side of the powerhead. That tire valve you're talking about on the VST is for reading electric fuel pump output pressure, using the correct tool. Yes, anytime you pull the oxygen sensor off for cleaning make sure to clean the carbon off the dog bone tube as well. That thing is a carbon magnet. If you need a service manual for your motor PM me your email and I'll send you one. Don't go messing around under the hood without one. You can click on the diagrams below to view the VST and the mechanical fuel pumps. The heart of the VST is the electric fuel pump that boost fuel pressure up to around 35 psi. The newer HPDI models would have another belt driven mechanical fuel pump that would boost fuel pressure up near 1000 psi.


-Mike

Thanks Mike,
My primer bulb does not pump up firm. My VST tank filter screen was very clean. The main fuel filter is upstream from this tank, so this should never be an issue. The O2 sensor dog bone was packed with carbon. I cleaned everything per a bulletin found on another site. I have 3 fuel pumps and some gaskets on order. Will re-post after they are installed and tested.
Dale

I replaced all 3 mechanical fuel pumps. One old one had a broken diaphram, allowing the gas/oil mixture to pour directly into the engine. Now the engine starts easy, and has a steady idle, but the idle speed is 1,100 rpm in neutral, warm. Target idle speed is 700 rpm. I can not lower the speed, as the idle screw is already backed off of the stop. I disconnected the throttle linkage to see is this was preventing the idle from going lower, but this also didn't help. The only thing left appears to be the six vertical screws on the intake linkage that are very heavily loctited. Any advice on this issue would also be greatly appreciated.
Dale

Sounds like a vacuum leak somewhere. Did you disassemble the VST? If so, when you put it back together, did you reuse the gasket, or did you replace it. Sometimes when the rubber gasket hits the air, it expands. Best thing to do is buy a new gasket, but you can also put it in the freezer for a while and it will shrink back to size. You can also check for a vacuum leak by spraying carb cleaner around suspected areas. If you hear an increase or decrease in idle speed, it will pinpoint your leak.

Good work on the fuel pumps. Yes they usually become suspect after about six years. Becomes routine maintenance to change them out. I assume you didn't have the high idle problem before you changed the fuel pumps out? You used the new gaskets with the new fuel pumps right ? It does sound like a possible vacuum leak. If the only thing you worked on was the fuel pumps I would suspect the gaskets on the fuel pumps (or lack there of...). You can spray some carb cleaner around them with the motor running and see if you get a change in RPM while spraying in that area. Other than that you can run through all the linkage and throttle body adjustments to make sure they're in spec. Also check the throttle position sensor for correct voltage and make sure it's in spec as well. You can adjust it to bring the voltage in spec ( .5v +/- .02v ) in the idle position. The RPMs will change as you move it into spec. Just use a digital multimeter and a couple of sewing pins if you don't have the test harness.

-Mike

My idle previously was all over. I did replace all 3 pump gaskets, and the VST gasket. I did not find a leak with the carb cleaner test. I did go through the idle set up procedure, and it's finally all fixed. The pickup adj,. screw was not allowing the cam roller to sit at the low idle mark. It starts, runs and idles great on the hose in the driveway. Can't wait to try it on the water. I believe that my fuel/oil consumption should go way down. Also, the excessive smoking. Thanks a lot Mike for all of your help.

Dale