90HP FOUR STROKE MERC

[rdghouse]

I HAVE A 90HP FOUR STROKE MERC 2001 MODEL I HAVE USED VERY LITTLE AND HAVE A PROBLEM WHEN FIRST STRATING OUT IT MISSES BADLY AND HAS NO POWER. IF YOU THROTTLE IT WIDE OPEN IN GEAR IT EVENTUALLY CLEARS OUT AND IS FINE THE REST OF THE DAY ANY BODY ELSE SEEN THIS?

 

[my new fishmaster]

Re: 90HP FOUR STROKE MERC

Sounds like my old saying fuel starvation. Its makes the most sense however you mention clearing out I have never had this problem. Could be you need to turn all the carb screws 1/4 clockwise or an 1/8th.

 

[hondon]

Re: 90HP FOUR STROKE MERC

Take another look at the starting procedure in your manual and ignore the part about the choke[it don't do anything anyway]. This engine has an automatic enrichiner and if you are advancinig the throttle as you would with a conventional two stroke,you are flooding it.

 

[wayne c.]

Re: 90HP FOUR STROKE MERC

I agree with hondon, unless you mean boat is in motion ( starting out ). When starting these engines leave in neutral, choke sets automatically. Do nothing with throttle--just turn the key. Engine will high idle for a few seconds, then settle to around 850 rpm in neutral. I currently own an '02 90 hp Merc 4-stroke, Before Merc had an 80 hp Yammy 4-stroke ('99 model ). It went to bottom of lake in a storm. Your engine has a Yamaha power head w/ merc lower unit. If its running rough after starting and warming up, then you have another problem. Good luck !

 

[ebubeck]

Re: 90HP FOUR STROKE MERC

I have this exact same problem. It seems that sometimes I would start the motor and I was missing on a cylinder, very rough with no power. Sometimes it would take just a couple of minutes and then instantaneously the problem dissapeared, like a switch was thrown or something broke loose. The longest this lasted was once for about 15 minutes and then nothing for the rest of the day. I have noticed that the problem is worse on cold days or after I have not used it for a few weeks - and sometimes not at all. Lucky for me my warrantee ran out on this motor 2 months ago and two days ago (after not running for 2 months) I started it and it will not get out of this mode. It is rough and I do not have enough power to get on plane. I am currently diagnosing to the best of my abilities - I have spark at the coils and will check the plugs tonight. After that it's the carburetors I suspect. They have an auto enrichener valve that apparently helps at start up by giving a richer mixture - it works by heating the electrothermal ram and thus closing off the excess fuel. Sounds like something that could easily get stuck on a cold day. Please help me out - I can't afford a trip to the dealer. I will post my final solution.