90hp Motor Question

[Reno G.]

I have a 2000 Mercury 90hp 2-stroke classic. When I fire it up for the first time in the morning it idles fine, but when I try to get the boat on plane the motor bogs down for a short period of time and then the RPM start to climb, sometimes slowly and then everything is fine. Motor runs up to about 5200-5400 RPMS and runs fine. I can run the motor the rest of the day without a hitch. What would cause this to happen on the initial WOT attempt only and then all is well.



Thanks everyone.

Reno

 

[Dan Smith2]

Hi Reno is your boat at Franzwas marine in Millville

 

[Reno G.]

No it is not.

 

[Bob Bourget2]

Are you priming the bulb before you start it? It sounds as though you are not letting it warm up enough before take-off, and it is a bit lean. Be sure to prime it, allow it to warm up {5 minutes}, then have a go at it.......

 

[Reno G.]

Yes, I prime bulb until it is rock hard before starting the engine. The last time I had the boat out I let the engine warm up for almost 10 minutes. Can it be something else? Thanks again for the help.



Reno

 

[Bob Bourget2]

Are you hearing any "lean sneeze" when at idle? Kind of like a backfire?

 

[TOMMY RICH]

Plugs or wires?

 

[Reno G.]

When I first start it up for the day, put in neutral and give it some gas it will sometimes die after running for 5-10 seconds and kind of sounds like a "lean sneeze" or backfire just before it dies. I figured this was because the engine is cold. It will typically start right back up and this cycle may happen a few times before the engine will stay running.



Plugs were changed last year, not sure when the wires were changed last. Current plugs only have about 15-20 hours on them.



Thanks.

Reno

 

[Bob Bourget2]

Back out spring-loaded, low speed mixture screws 1/4 turn and let me know how it responds.....one on each of the three carbs, located at the top, port side.

 

[Reno G.]

I will try that. Thank you Bob, it is so great to have you on this website.



Reno

 

[TOMMY RICH]

The 90 is a very cold natured animal.

I just about always at first start have to choke it for a few seconds then may have to tap it until she's warmed up.

 

[Reno G.]

I backed off the low speed mixture screws 1/4 turn yesterday. The idle appears to be a little rougher and the engine still hesitates on the first run of the morning. After the first run she ran like a champ.



Thanks.

Reno

 

[Bob Bourget2]

A slight hesitation when cold is normal. As long as that is the ONLY issue, give it a little extra fuel, read "hit the choke" a couple more times before the initial take-off.

 

[Reno G.]

Thank you everyone.



Reno