1999 Saltwater series II Yamaha Problem

[jidigill]

The last time I took my boat out last year my motor was not running like usual. Instead of running at 5200 rpm it would only go to 4700 rpm. I winterized, put in new plugs, new water/fuel separator and filter. I took it out this year for the first time, it was running nice for about the first mile, then the motor bogged down and dropped in rpms, almost like a cylinder isn't firing, then it would rev up and bog back down. I thought it was water in the fuel, so I emptied all the fuel, put in new fuel. I took it out today; for about the first mile it was running fine, then it bogged down and at 3/4 throttle, it was only going about 15 miles per hour, like it wasn't running on all cylinders. Yet, every once in a while it would rev up like the cylinder was firing again and then bog back down and drop in speed. At one point it seemed to be running fine again for about 5 minutes and then the problem happened again, and I took it back to port at 15 mph at 3/4 throttle. Any answers? My friend seems to think maybe one of the coils are going, but I'm not sure. It revs up, then down, up, down...???? The motor is a 1999 Yamaha 150hp Saltwater Series II.

 

[birdbrain]

Re: 1999 Saltwater series II Yamaha Problem

I'm not the expert on this forum so let them verify...
The high pressure fuel pump which resides in the Vapor Surpression Tank has a filter on the bottom. There is also a filter on the fuel pressure regulator which is mounted on the top of the VST, clean them. Things to note: use the same type of clamps on the hoses that supply fuel to the injector fuel rail since it is a high pressure line if you need to remove them to get into the VST, regular hose clamps are risky. If you look on yamahamotors.com under parts, you can locate the items discussed above from blow up drawings.
Lastly, there are screens on the injectors that should be serviced as well.
To be proper, you should first test the fuel pressure to see if this is the issue, but I bet if this has never been serviced, it's the issue. I have the 1999, 200hp version of this engine.

 

[jidigill]

Re: 1999 Saltwater series II Yamaha Problem

BirdBrain - Thanks for your reply. Is your motor an Oil injected carbuerated version? Mine is, I pump up the fuel ball, have 3 Carbs, oil injected. It seems they made 3 different models that year. One of my friends thinks it may have to do with the piston rings since the problem seems to happen after the engine has warmed a bit. I was driving back to port and it was running very slow, low rpms, 3/4 throttle, and all of a sudden it would "kick in", you could hear the motor rev up, sound normal, and the speed and rpms would rise, but only for about 20 seconds, then it would bog back down. ????

 

[rodbolt]

Re: 1999 Saltwater series II Yamaha Problem

sounds like you have clogged carbs or a bad lift pump or a restriction in the fuel line. pay no attention to buddies that have no knowledge, but keep running it like that and you will beable to post about the cost of pistons while fixing the original problem.
trust me on that.
I maybe have seen 2 or 3 ign coils on V yamahas actually failed in the past 10 years or so.

 

[ToesUp]

Re: 1999 Saltwater series II Yamaha Problem

I'm a pretty new boat owner myself so I'm no expert but my dad told me he had the same problem with our boat on its last outing last year. When I pulled the boat from the water and went to winterize it I found that one plug wire had fallen off and the others were very lose and came off the plugs pretty easy so I replaced all the boots. Maybe one of your boots is worn and when the motor warms up it loses contact with the plug? Just a guess, like I said I'm far from an expert.

 

[freemachinist]

Re: 1999 Saltwater series II Yamaha Problem

I have a '99 yamaha 115hp saltwater as well. This problem has been bothering me as well. With my motor it takes about 20 minutes to bog down, after its heated up. Just as jidigill mentioned. I have replaced the primer bulb (which had a pin hole leak) the water separator and the plugs. Next time out I had the same result. I did notice when I push the key/choke in, the motor smoothed out a bit. If I give it more throttle the motor hesitates a bit and usually gives back what it took.
I was hoping all I had to do was tune the carbs, or perhaps "sync" them properly. I am no marine mechanic but I am a machinist, I'm not scared to pull anything off and check. Birdbrain mentioned cleaning some screens, I'll look at the exploded drawings on Yamaha.com. and see if I have the confidence to try it.
How do I test the fuel pressure, since someone mentioned it?
Does anyone know if the primer bulb can break up as one squeezes it? Meaning, if my old one had a pin hole leak and looked as bad as a dry rotted tire, is there a chance a piece of it could be fouling my carb jets? Oh...are zip ties suitable to secure the primer bulb to the fuel line or use those weird metal crimps Yamaha does? Thanks.

 

[rodbolt]

Re: 1999 Saltwater series II Yamaha Problem

zip ties are more than adequate, just keep an eye on them at least once a year for sun damage.
very possible you have trash in the carb, doesnt take much.
fuel pumps I reccomend replacing every 3 years as routine maint.
replacing the fuel pumps and rebuilding the carbs on the 150 is a 2 hour project and about an hour and a half on the 115.
if the needle valves are not leaking(flooding the engine) then usually you can get by with just the float chamber gasket as opposed to a very expensive carb kit.
there is not a lot to the V late style carbs.
however ALL circuits supply fuel at higher speeds and the clogging of any or all jets will create a lean condition for that cylinder.
by tapping the choke you forced it rich,bypassing ALL normal carb circuits. the increase in speed indicates a lean condition existed as the air was already there it just needed the extra fuel.
had the air fuel mix in the crankcase been correct the choke would have caused an instant drop in RPM not an increase.

 

[freemachinist]

Re: 1999 Saltwater series II Yamaha Problem

Wow that was a fast reply. I wish i was with my boat right now, I could look at some of that stuff. I am assuming that I have a small air leak somewhere if debris isn't the culprit. Change the fuel pump and check the float bowl gaskets and the bowl itself. Sounds simple enough, Thank you for the advice. I will post as soon as i have something solid to post about.
As for pushing the choke....only when the engine is at idle does the choke smooth out the rough idling, i.e. no wake zones. She shakes a bit until i push the choke, smooths out for a few seconds and begins its rough idle again. Under WOT pushing the choke does drop the rpm.

 

[matveim]

Re: 1999 Saltwater series II Yamaha Problem 150 hp

Re: 1999 Saltwater series II Yamaha Problem 150 hp

i tray to start but the motor don't going on, i check the spart current and no current when i do the start. please some bady help me....

 

[rodbolt]

Re: 1999 Saltwater series II Yamaha Problem

start a new thread posting the problem AND a model number.

 

[matveim]

Re: 1999 Saltwater series II Yamaha Problem

start a new thread posting the problem AND a model number.

look i don-t know to much english so i tray explane the problem. maybe you can help me with my problen. 1999 150 hp yamaha salt water serie 2, i try to start but noting, looks like current problen, i check the spart when i did the start and no show current
thanks

 

[99yam40]

Re: 1999 Saltwater series II Yamaha Problem

Click on this link

http://forums.iboats.com/forumdisplay.php?f=26

and then click on the create new post button

and then start asking you questions

 

[rodbolt]

Re: 1999 Saltwater series II Yamaha Problem

I am married to a venezuelan that speaks decent english. I speak NO spanish, well enough to get a cool refreshing beverage.
I understand the language barrier.
if you speak spanish my wife is also a translator.
if not keep posting, usually I am patient.