88 Johnson 40 hp runs/idles fine but spits and sputters when you open it up

[CatriderF7]

I just bought a 88 pontoon with a 40 horse johnson on it today for $500. It starts up and cruises at low speeds fine but when you give it full throttle it spits and sputters until you back off. im picking the boat up tomorrow and plan on pulling the plugs and checking them out right away and checking compression. the guy said the plugs are most likely original and that it sat for 8-9 years before he started it up on old gas last year and this problem started happening. Im going to fill it up with premium and seafoam before running it and change the plugs. any other maintenance i should do before putting it in the water?

Thanks in advance

 

[Monte1961]

Re: 88 Johnson 40 hp runs/idles fine but spits and sputters when you open it up

Plan on carb/s overhaul. Seeing how it sat so long I would also change impeller and check lower unit for water. Don't be surprised if it doesn't have water in it yet. After a good day of running, pull the drain/fill plug and check it again. Good luck and post back!

 

[CatriderF7]

Re: 88 Johnson 40 hp runs/idles fine but spits and sputters when you open it up

thanks, ill check the fluid before and after i get it into the water. Ill put new plugs in it and pull the carb apart and try cleaning it out. This is my first outboard, I Probably wont have it in the water til early next week, ill do as much checking it out as i can over the weekend, plus im redoing the seating and putting a stereo system in it.

 

[CatriderF7]

Re: 88 Johnson 40 hp runs/idles fine but spits and sputters when you open it up

well i got a set of rabbit ears and got it started up after cleaning a massive mouse nest out from in and around the air box, and it seemed to run alright, only issue is its not spitting the water out of the holes its supposed to be coming from. The water is coming out farther up the lower unit right below where it attaches to the boat. and also i went out today and looked at it and theres a small puddle of oil that leaked from behind the prop. i assume theres a seal behind the prop, but can anyone help witht the water issue?

 

[Daviet]

Re: 88 Johnson 40 hp runs/idles fine but spits and sputters when you open it up

When running on muffs, you will not get much, if any, water out of the exhaust ports. The exhaust housing is empty and all the water comes out at the prop.
When running on muffs you will get some excess oil/gas leaksge out of the exhaust housing, normal operation, it should be black and have a gas smell to it.