Cant get full throttle under load

[dave524]

Hello to all. I am having problems with my 1996 Johnson 88 SPL. I dewinterized it today and while starting to run it out discovered that it bogs under a load. The best way to describe the condition to you is it feels like I am pulling a tree stump when I give it full throttle. Now what I have checked. Plugs are new, fuel is fresh, ran it dry last year and fogged motor. Prop turns freely, and when motor is in gear, you cal turn over the engine by turning the prop. Running the motor out od the water and in gear ( rabbit ears) Runs fine. runs fine in neutral, full rpm range. just when u want to go, it wont. any ideas ? This motor ran great last season with absolutly no problems. Thanks in advance for your help.

 

[Silvertip]

Re: Cant get full throttle under load

You probably have a fouled carb. Running an engine out of fuel does not really run it out of fuel. Some remains in the carb only to turn to varnish and gunk if a fuel conditioner like Stabil or SeaFoam was not run through the engine before you shut if off. As for running fine on muffs, I suspect is not running fine on muffs. An engine running on half its cylinders will rev freely with no load. I suggest you pull the plugs and check them. I'm betting you find at least one that is like brand new because it is not getting fuel (or at least not enough) while the others look normal. I think you are due for a carb rebuild. And by all means do not run the engine in its current condition because no fuel or not enough fuel also means it is not getting enough lubrication which can destroy an otherwise perfectly good engine.

 

[kenmyfam]

Re: Cant get full throttle under load

Does sound like a fuel delivery issue or maybe a powerpack.

 

[dave524]

Re: Cant get full throttle under load

Are these carbs easy to rebuild ? By powerpack, do you mean coil ?

 

[tashasdaddy]

Re: Cant get full throttle under load

Start at the beginning of trouble shooting. check your compression, and spark on all 4 cylinders. i would look for at least 120 psi and within 10 % of each other. spark needs to jump 1/2 inch. any auto parts store sells these http://www.shopperschoice.com/item_name_Lisle-Ignition-Spark-Tester_item_372001.html?source=froogle

if all is good then go to the fuel system, i am going to bet you have some clogged high speed jets. running it dry, pulled any crud into the high speed jet and it sat there all winter and hardened.

read this. http://forums.iboats.com/showthread.php?t=244013

 

[jimmy120]

Re: Cant get full throttle under load

Did you ever come ups with solution to your problem? My motor an "850 Mercury" is doing the same. Runs great out of the water, but would not go to full throttle