HELP Yamaha 9.9 4stroke!!!

[metalmanzr2]

Ok, firs off what I have: Its a 94 yamaha 9.9 4stroke motor (2 cylnder). Problems: Well I first got the boat about a month ago. Motor only has about 12 hours on it. Bought from an elderly couple that let it sit with gas in the carb/lines and didnt want to mess with fixing it. I cleaned the carb put plugs in, oil change, new gas cap, filter, etc. First time I started it, it would idle fine, but when you take off it would run, then cut out and idle down by itself, kind of like it was starving for fuel. Thats when I put the new gascap on. That helped, but still not right. Ok, so now when you start it it wont idle low. It idles up then down randomly. When out rideing around, it still cuts out and idles down to alower speed by its self. Ive cleaned the carb several times, checked fuel lines, plugs. I have no idea what is wronge with this motor. Anyone out there have any ideas at all? Im open to any and all sugestions. Like I stated earlier, it sat with gas in the lines/carb (for about a year and a half Im told) but they apear to be clean. Any Ideas at all PLEASE HELP<br /><br />Thanks<br /><br />Joey Hamlin<br />92 Bass Tracker Pontoon

 

[metalmanzr2]

Re: HELP Yamaha 9.9 4stroke!!!

^^^^BUMP^^^^

 

[steelespike]

Re: HELP Yamaha 9.9 4stroke!!!

You could have one plug cutting out.Ignition problem or even a bad plug.Do both plugs seem<br />OK? <br />There could still be a fuel supply problem.Check fuel pump output to carb.Does the primer bulb pump up and stay up?If it helps when you poke the choke it indicates a fuel problem.

 

[Forktail]

Re: HELP Yamaha 9.9 4stroke!!!

First eliminate all potential fuel problems. Make sure you have fresh fuel and the old fuel lines are purged of the old fuel. Make sure the tank is vented and the pick-up screen is not plugged. The primer bulb must work. Both ends of the fuel hose must not suck air or leak fuel at the fittings (the o-rings can go bad). Try squeezing the primer bulb when it's running. If this helps, she's not getting enough fuel and possible bad or plugged fuel pump. Hopefully the carb is adjusted perfectly.<br /><br />Next is electrical. Look for the obvious wear or break in wires, spark plugs, plug gap, etc. You'll need a Yamaha mechanic to diagnose anything else major unless you're apt and have the tools.<br /><br />The warning system could be activating. Rough idle and stalling are sure signs. Also the thermostat could be stuck or clogged. Make sure you used the right oil.<br /><br />These are great little motors. Good luck.

 

[metalmanzr2]

Re: HELP Yamaha 9.9 4stroke!!!

Both plugs are new and gaped right. Im going to try replacing them agin tomorow. The fuel lines are clean and clear. The pump is pumping just fine. After takeing it off the motor and pumping it by hand you can feel it working when placeing your finger over the inlet and outlet. As far as checking with the choke, I cant because the choke is electric. Is there a chance that the choke may be sticking and not working causing these problems? Is there an easy way to check and see if the thermostat is working? <br /><br />Thanks for the help

 

[metalmanzr2]

Re: HELP Yamaha 9.9 4stroke!!!

^^^^BUMP^^^^

 

[steelespike]

Re: HELP Yamaha 9.9 4stroke!!!

You need to examine plugs new or not to determine<br />how they are burning.<br />I believe you can push to choke whether electric or not.You can also spray some WD40 in carb see<br />if it helps.

 

[metalmanzr2]

Re: HELP Yamaha 9.9 4stroke!!!

I cant do anything with the choke, Its electric and I have no contorls for it on the console. It automaticly does it its self. the only thing that I could do with it is unplug it, but I dont think that would do anything. Im going down to the boat today with some tools, and a new set of plugs. If the old ones look like there not burning right Im going to replace them. Ill try some carb cleaner or wd40 in the carb while its running as well

 

[JB]

Re: HELP Yamaha 9.9 4stroke!!!

Your "choke" is an enrichment system operated by temperature controlled vacuum valves. Leave it be. <br /><br />Don't mess with that engine without a manual. The carb/fuel system is something you never saw before.<br /><br />The best you can do is ensure that the fuel system is clean and that all of the spider web of vacuum lines and temp switches are not leaking and are clean.<br /><br />Do NOT spray WD-40 into a 4 stroke carb. Straight gasoline, maybe, but NO OIL!.<br /><br />Good luck.

 

[metalmanzr2]

Re: HELP Yamaha 9.9 4stroke!!!

There isnt a "web" of vacume lines. the choke is electric. Has two wires running into it. as for vacume lines, I dont see many on the motor at all. Ive taken them all off one by one and ckecked to see that they were clear and not blocked. Went down today to mess with the boat, and It wouldnt even start for me. Usualy fires right up if I idle it up some. this time nothing. I didnt try any starting fluid because I didnt have any with me. I was going to replace the plugs, but they were out of the nkg plugs at the store I went to, so I have to do that later. Is it posible that the motor if vapor locking. Could that be a causeing it to not start and when it does start not run right. Ive tried to find a manual for the motor but cant. All the manuals Ive found are for eather the pre 90 motors that were not 4 stroke, or there not for the 4 stroke 94 motor. <br /><br />Joey

 

[Bear]

Re: HELP Yamaha 9.9 4stroke!!!

You have a manual choke lever too? Pull it out and see if there is any difference.

 

[JB]

Re: HELP Yamaha 9.9 4stroke!!!

Howdy Metalmanzr2.<br /><br />Sorry about that. I assumed that your '94 is similar to my '86 Yammy 9.9 4 stroke. <br /><br />The carb enrichment system is a nightmare on mine. Sounds like yours is a serious improvement.<br /><br />With this new info I would look into the fuel pump.<br /><br />Good luck.

 

[metalmanzr2]

Re: HELP Yamaha 9.9 4stroke!!!

Thats alright JB thanks for trying to help. As for the choke, I have NO controle over it what so ever. The only thing I can do to it is unplug it. Ive been thinking its the fuel pump my self. I pump the primer ball and it will fire over once. then nothing, check the primer ball and it has no preasure. Its just started doing this, before it had preasure on it like it should. I originaly thought it was acting like a fuel pump was going out. 125 bucks for a fuel pump thats no bigger than a D battery, and its all plastic. Nothings cheap these days. When I get the pump, Ill let you guys know if it fixed it

 

[Forktail]

Re: HELP Yamaha 9.9 4stroke!!!

You may be able to disassemble that fuel pump and clean it yourself. My 87, 89 and '02 9.9 4-strokes have a two-piece metal/plastic pump. I think I remember having my 87 apart long ago.<br /><br />Also there is a ventilation tube on the carb that ventilates the carb fuel bowl. Make sure its not plugged.<br /><br />I believe the electric choke with the two wires operates a solenoid and a little plunger. You can take off the solenoid by removing the two screws and keeper plate. Make sure the plunger is operating freely. There are no vacuume lines or manual choke levers on this sweetheart. <br /><br />There is an accellerator pump on these carbs, which must be operating properly. Since the accellerator pump is at the bottom of the carb, it can fail easily if the motor has sat for long periods with untreated fuel (stabilized or drained). You should hear the pump squirt fuel into the carb as you turn the throttle fast or move the throttle lever fast.<br /><br />It does sound like a fuel starvation problem. Make sure your fuel pickup tube isn't plugged and the tank is vented properly. <br /><br />One more thing if you have a little in-line fuel filter.....when you changed the fuel filter, make sure you installed the new in the right direction. The filter has an arrow on it indicating which direciton the fuel flows. The arrow should go in the direction to the carb. It won't work the other way. <br /><br />Good luck.

 

[metalmanzr2]

Re: HELP Yamaha 9.9 4stroke!!!

I had the pump off once before. I believe that it was a sealed unit. I asked the parts guy and he sead that they dont make rebuild kits for it so I assume it is sealed. Im going to check the accelerator pump agin and make sure its working properly. Thanks for the help guys<br /><br />Joey

 

[metalmanzr2]

Re: HELP Yamaha 9.9 4stroke!!!

Well I worked on the boat today. After putting a new set of plugs in the motor will start now, but still wont idle right. I looked at the old plugs. They look realitvly clean but on the white part (dont remember the technical name for it now) inside the tip of the plug. Part of it is white, and the other half of it is a redish brown rusty looking color. One half is white and the other discolored, is this normal. While there I also checked the ball on the gas line to make sure it had preasure. It dosnt keap much preasure, but when you pump it, it makes no difference in how the motor runs. when I do pump it though, I can hear gas moveing in the tank. I checked and the hose is on the right way. Any Ideas<br /><br />Thanks<br /><br />Joey

 

[metalmanzr2]

Re: HELP Yamaha 9.9 4stroke!!!

^^^^BUMP^^^^

 

[harrison20002]

Re: HELP Yamaha 9.9 4stroke!!!

Metalmanzr2: As I was reading through your posts I kept thinking Fuel Starvation. I think Forktail may have your answer. Start with your intank filter, pickup tube, fuel coupler and right up the line to your fuel pump. Don't put out that hundred-twentyfive if you don't have to. Hope this helps a little. Happy Boating,Hal

 

[metalmanzr2]

Re: HELP Yamaha 9.9 4stroke!!!

Thats what Ive been thinking it was too. Ive got another tank and new fuel line, Im going to put on and try that to see if it helps. Im also going to replace the fuel line inside the motor. Ill keap you all posted

 

[snascar2424]

Re: HELP Yamaha 9.9 4stroke!!!

I hope everyone reads this to fix their 9.9 yamaha hard starting problem. The very first thing to clear up yamaha put out a bad design on the choke. I'am a machinest and I can build the fix for these carbs but it cost 125.00 per unit. I just got through the testing phase of the fix and I had a bastard that just would not start without a manual choke. In the morning i now just prime the bulb and pull the choke on and bingo she starts. Nobody sells this but i will start manufacturing this fix in the coming months. If you have one of these motors that has a electric choke no matter how much you adjust it just seems never to work quit right. If you are interested you can contact me scott_alliedscrewmachine@comcast.net. I need to see what interest their is before making a whole bunch of parts that may not sell. I knew if i built this it would fix the problem and it did and it can fix your as well. The best thing about it the fix is you eliminate a solenoid that sits on the carb and you can unplug, you won't be needing it anymore. The only thing you will need to do it drill a hole it the side of the motor for the choke rod. I would say on a scale of 1-10 your looking at a 3 on skill needed to do this. The other mods can be done at my shop and sent back to you.
I hope this help some of you guys out their. This will only fix the choke problem and if you have other problems it will not solve them. I know these are good motors and will give you years of service after all they are a 4 stroke.