25 HP Johnson 80s model won't pee in full throttle

[tookie_thepit]

Hello, i recently bought a boat with a 25 hp johnson on the back. It had been sitting for a year maybe 2 before we started it up, first time we put the muffs on and it was peeing water, then we would turn it off and start it back up and it stopped...so we figured the impeller was shot in it...we ripped the bottom unit off and replaced the impeller put all back together and fired it up and sure enough it would pee water, Well yesterday I took it out to the lake for the first time and it ran great had a steady stream all the way up to just about full throttle, then when i really gave her the nuts the water would just trinkle out and eventually stop coming out all together, then id slow down and it would start smoking like a mother F****** but the pee would start up again, basically when its in full throttle it stops peeing, meaning it stops cooling correct? hence all the smoke coming out, shouldn't it get a stronger stream the faster you go???? any help would be well appreicaited!

 

[jbjennings]

Re: 25 HP Johnson 80s model won't pee in full throttle

My thoughts are that you have a leak in the exhaust cover seals, and upon full throttle, the motor makes enough pressure to force enough air into the water jackets to stop water flow. Obviously, you could overheat and ruin the motor as you already know, so you're wise to find the problem. In this case, I'd replace the exhaust cover seals, and if the problem persists, conside replacing the head gasket as well.
If head gasket and exhaust seals don't fix it, you have a bad pump housing, bad water tube grommet under the powerhead, or possibly even another problem. Look for evidence of water entry into the cylinders due to a bad head gasket, such as steam-cleaned spark plugs or rust on a spark plug. Hard to identify bad exhaust cover seals, but if the motor has been overheated in the past, it's a very likely problem.
Good luck,
JBJ

 

[Cofe]

Re: 25 HP Johnson 80s model won't pee in full throttle

Welcome to iboats tookie!
Here is a thread that was posted earlier. We are still waiting on the results from what he found, but this thread will give you some information for troubleshooting. http://forums.iboats.com/showthread.php?t=486302

 

[tookie_thepit]

Re: 25 HP Johnson 80s model won't pee in full throttle

alright, hopefully can look at it this weekend ill let ya know what i find out thanks for the replies!!!!