Yamaha Problem

[cjg]

All of a sudden yesterday my motor took forever to start<br />It now will not start without lifting the lever (Remote 703)(Choke I assume)but as soon as I put the lever back down it cuts out unless I am lucky enough to quickly get into gear and go<br />It's as if the idle is too low but nothing has been done to change anything<br />When I got home I took off the cover and found fuel in the bottom of the pan<br />I checked all fuel lines and pumps but could not see any leaks<br />Before this happened it was going fine except it would not exceed 4000 rpm's which I knew was not correct but as it was running ok I decided to leave that problem until next annual service<br />I recently changed all the plugs and it was going ok<br />I have posted previously about the low rpm's but this problem is new <br />The motor is a Yamaha V6 Oil Injected 150hp 1987<br />Any help is always appreciated<br />

 

[JB]

Re: Yamaha Problem

G'Day, CJG.<br /><br />You may have carb trouble, like a sticking float or loose part in one of your carbs.<br /><br />Let's narrow things down some. Get her started ( I think the lever is a fast idle lever for warm-up).<br /><br />Carefully remove each spark plug wire and note whether you can get a 1/2" to 3/4" arc to the block, and whether the idle speed drops or not.<br /><br />If idle does not drop that cylinder is not making power. If it has a good spark it is carb trouble.<br /><br />Let us know and we can move forward from there.<br /><br />Good luck.

 

[cjg]

Re: Yamaha Problem

Thanks JB<br />Do I just take the lead off the spark plug when it is running ?<br /><br />Not sure what you mean by arc ?<br /><br />I keep hearing about carb cleaner...would this be ok and would this be an easier way for me (novice) to fix the problem if it is the carbs as most people are saying<br />I worry about doing further damage if I use any cleaner etc..<br /><br />Could it also be the fuel pumps ?<br /><br />I will try what you said asap and let you know

 

[KIWI MERCMAN]

Re: Yamaha Problem

cjg<br />Just a add on to Jb's post , be careful when you take off the plug leads, as you stated that you had fuel in the bottom pan, you dont need alot of fumes for a big bang.<br />JB :FYI not all V6's drop rpm when you take off a plug lead at idle due to exhaust tuning and scavenging, some can increase in rpm. You really need a good ear for the engine to hear what is going on.<br />I agree with JB, you could have a carb problem also.<br />The arc he is talking about is the spark from the lead to the plug, good and blue runs true.<br /><br />Could also be compression on one cly, always pays to check comps as it is hard to fix something when you are not starting with a full deck of cards.<br /><br />KIWI

 

[cjg]

Re: Yamaha Problem

Ok spark good what next ???<br />Remember I have had a compression test done and all OK<br /><br />Help

 

[cjg]

Re: Yamaha Problem

 

[butlp]

Re: Yamaha Problem

CJG<br />You really need to buy a manual for your motor. It will pay for it self and will give you the confidence to delve deeper into your engine.<br /><br />Strip and clean the carbs and when you re-assemble follow the manuals procedure to adjust the carbs and set the timing.<br /><br />Good luck!

 

[cjg]

Re: Yamaha Problem

An update..<br />When I prime the engine I noticed that fuel was coming out from the carb area into the pan. I took the plastic carb cover off and noticed that when priming, fuel was coming out of the bottom carb. I can only see 3 carbs one on top of another and it is coming out of the bottom one. I assume they must be dual carbs maybe as it is a V6.<br />Also regarding my problem with only getting 3500 -4000 rpm's it has been suggested that maybe it's the small 24 lite fuel tanks that I am using with clip on hose connectors. The diameter of the opening with this setup is only 3mm or so and I was told for my size motor it should be 10mm for the fuel. Does this make any sense to anyone ??<br />

 

[cjg]

Re: Yamaha Problem

 

[John from Madison CT]

Re: Yamaha Problem

Sounds like a stuck Needle and Seat, if Gas is pouring out of the carbs.<br /><br />I recommend a carb cleaning. I have however unstuck a stuck needle and seat the cheap and easy way, and that is to remove the large screw at the bottom of the carb. and pump the primer bulb. This will likely purge the crud that causes the needle to be stuck. Try that.<br /><br />John

 

[cjg]

Re: Yamaha Problem

Ok so I have removed all 6 carbs(3x2)and have bought some carb cleaner and will attempt to clean them myself tomorrow.<br />Any tips ??

 

[mrs6446]

Re: Yamaha Problem

anyone know how to adjust the carbs on a 40 h.p Yamaha outboard 2001 2 stroke, i really need to get it fixed today, but nobody has the manual in stock, thanks a bunch