engine can only go 4000rpm

[Mohsali]

Hi, I've got Mercury 200HP model V6 1985. Bought it secondhand, replace most of the electrical system (90%). Engine runs fine but up to 4000rpm. Help

 

[SpinnerBait_Nut]

Re: engine can only go 4000rpm

First I would check and see if thottle is going WOT without engine running.<br /><br />Might have slipped and not going all the way.

 

[KCLOST]

Re: engine can only go 4000rpm

What prop do you have on the motor, and what type of boat are you pushing (length, weight, etc.)?

 

[rickdb1boat]

Re: engine can only go 4000rpm

What size and type boat is it on?

 

[Mohsali]

Re: engine can only go 4000rpm

I've got 18 footer explorer model weight 550kg. Plug #5 is wet, others normal as mention in the repair manual. Check the trottle cable but seem o.k. I've got 141/4" propellor just for infor. I don't have the necessary tools to check the wot. Maybe u guys can advise more. Thanks

 

[jim dozier]

Re: engine can only go 4000rpm

You have the tools to check for wide open throttle, its your eyeballs. Remove any air box cover on the carb throats and look into the carb throats while the throttle at the helm is all the way open. Your carb butterflies should be parallel to air flow, if they aren't, something in the linkage is amiss, then you may or may not have the tools to fix it but at least you'll know where the problem lies.

 

[Mohsali]

Re: engine can only go 4000rpm

Carbs butterflies paralleel to air flow. But the the pump water pump fail to inject water, might need to replace impellar. Engine start to pick-up but no watre coming out so I stop the engine. Thanks for the idea cos I bought the engine with zero knowledge on outboard engine.

 

[Murp]

Re: engine can only go 4000rpm

Hi ,you said you bought it second hand,did you ever have it over 4000 RPM,like 4500 or over, the reason is if your Propeller has to much pitch ,the motor is working to hard and that’s all the RPM you will get,it happen to me years back ,the boat had a 21 Pitch prop,it need it a 17 pitch, solved the problem

 

[rickdb1boat]

Re: engine can only go 4000rpm

Run a compression test before you do anything else. That may tell the story. Post results...<br /><br />EDIT: Wow, didn't see that post was that old..

 

[gss036]

Re: engine can only go 4000rpm

It is an old post,<br /> I WOULD think that if the engine had been run at 4000 RPM witout water, it was probably seizing from overheating.

 

[Mohsali]

Re: engine can only go 4000rpm

Guys thank alot. Got engine running after doing some setting. RPM 4500 at 40 knots. Good enough for me. Will fine tune engine again. Bye