Sluggish Yamaha

[Retro]

Still having problems getting my Yamaha to accelerate out of the hole right away. It starts great, will go into troll mode with no problems. When I gun it, all of a sudden, it dies. THere is a point in the throttle where it'll drop down in RPM's quite a bit, and barely stay running. THis is usually when the throttle is positioned past trolling speed. I'll give it a couple of chokes, and all of a sudden it takes off, and it will go fine out of the hole after that. Until I turn it off or let it sit for extended periods of time.<br /><br />THe fuel pump is new, but is it getting air in the system from somewhere else? Could it be a faulty line from the tank, a bad primer bulb, or even a bad tank? What's the best way to isolate where the air is coming from?

 

[JB]

Re: Sluggish Yamaha

Ahoy, Retro. Maybe you are getting air in the fuel and maybe you are simply getting brief fuel starvation when demand increases. In addition to the tank, pick-up, primer ball,fuel lines and any filter(s) in the system, I would check float levels and check for obstructions in the crankcase to pump passage. Look for small cracks or kinks in rubber lines and ball pumps.<br />Good luck.<br />JB

 

[Retro]

Re: Sluggish Yamaha

How difficult is it to adjust the floats? First thing I was going to do is change the fuel lines off the connector from the fuel tank hose, and then the hoses to the carbs. They are about 9 years old, so it can't hurt to start there.<br /><br />A friend pointed out that I have a tendency to stop the engine at full RPM's rather then idle the engine down before turning the key. Could this be a problem, maybe leaving too much fuel in system upon restarting the engine? How would the fact that choking the engine takes care of the problem affect this theory?<br /><br />Thanks for all the help. It is most appreciative!

 

[Dhadley]

Re: Sluggish Yamaha

What fuel are you using?<br /><br />Good luck!

 

[Retro]

Re: Sluggish Yamaha

87 grade, the cheapest.

 

[Dhadley]

Re: Sluggish Yamaha

Because you can correct the problem with the choke, it indicates a lean condition. Have you tried cleaning the carbs and installing new kits? Some of the Yamahas were very fickle and a little water in the fuel will drive you crazy. JB's right about the float level too. Especially on a boat that has a lot of bow rise on acceleration.<br /><br />Good luck!

 

[coolblue1152]

Re: Sluggish Yamaha

I have the same problem with a 87 yamha 115. In my case I have 2 engines pulling from one tank so it is not the fuel. The other engine runs fine. I'm still looking. Had the same problem sometimes on a 200 suzki. The promblem went away on that one. I'm going to try and clean the carbs.

 

[jim dozier]

Re: Sluggish Yamaha

Dhadley is right I think, and from the description it sounds like the mid-range jets are the culprit. It will idle, and if it every gets past mid-range it will scoot but it can't get past mid-range without the help of the choke. I vote for a carb tear down.

 

[coolblue1152]

Re: Sluggish Yamaha

I pulled the carbs on mine. The idle jet pulls fuel through the bottom of the float bowl. Fuel would not pour through this passage and I could not see light through it. After a blast of carb cleanner then a blast of air I could see through. This is the mid range supply of fuel also. I hope this is it. At least it will idle now. I'll let you know tomorrow. Im trying it tonight.

 

[coolblue1152]

Re: Sluggish Yamaha

Port motor ran great no more having to work the choke. The starboard engine ran poor for about 15 min. I hit a boat wake from another boat and it took off also. That leads me to believe it was something with the carb. I have water in the gas from a missing fuel vent cover. After that they both ran great all night. Got 6 big king fish in the process.