WOT problem on 85hp Johnson

[boating2fish]

When in the lake and taking off motor runs fine till the rpms get to 4000 to 4200 then it just stays there for a second then begins to fall back to around 3800 rpms. I still have throttle left but there is no response from the engine. I can not get back to the 4000+ mark unless I back off of the throttle some then go back into it. Could this be a coil falling off at the higher rpms?<br />Any suggestions would be helpful.

 

[Dhadley]

Re: WOT problem on 85hp Johnson

Has the motor been sitting all winter?

 

[boating2fish]

Re: WOT problem on 85hp Johnson

no the boat has not sit all winter long. I have even cleaned the carbs twice with no change.

 

[boating2fish]

Re: WOT problem on 85hp Johnson

^

 

[Dhadley]

Re: WOT problem on 85hp Johnson

Well nuts! I was hoping it was something simple. It could very well be ignition as you suspect. <br /><br />Check the timer base to make sure its not sticking.

 

[OBJ]

Re: WOT problem on 85hp Johnson

2fish...have you done the usual compression tests and made sure the engine isn't overheating? Maybe a check of fuel lines may be in order???? Hard fuel lines lose their tenacity (theres' a word Dhadley)and can leak where they connect. Fuel can vented good? I'm with Dhadley....something simple. Or a coil going south when it hots up.

 

[boating2fish]

Re: WOT problem on 85hp Johnson

found a coil dropping out at high rpms with the timing light going down the lake. Going to replace and will let everyone know the outcome.

 

[boating2fish]

Re: WOT problem on 85hp Johnson

replaced the coil and put new plugs in. I guess you say it runs like a champ. Top rpms is 5100 now so it looks like I new to change props to get to about 5500 rpms. That was with two people in the boat I'm going to see what it is with just me so I can make sure what size prop I need for the right rpms. Thanks for all the help.