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1980 Johnson 70hp wont run under load

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newbreed

New member
I have a 1980 Johnson 70 seahorse i'm having problems with. it runs good with the ear muffs on, i can put it in foward or reverse no problem. but when i put it on the lake or in a barrel of water it bogges down and wont run at all. i have checked compression all 3 cylinders have 130-135 and all 3 have good spark. water pumps out really well with muffs and in water. next on the list is carburetors...tonight me and my dad were messing around with them, before we took them off we had the air intake manifold off so you could see all the carbs on the engine. we had the engine started and he sprayed a tiny bit of carb cleaner in the top one and it reved the engine, he sprayed into the middle one and it reved the engine....but when he sprayed a tiny bit into the lower carburetor the engine died insteantly. so we started with that one took it off cleaned it replaced gaskets and float and what not. we put it back on and it did the same thing . anyone have any ideas why its doing this. or why it dies if we spray a tiny bit of carburetor cleaner into the lower carburetor?? or have any suggestions on what we should be looking for...we are planning on rebuilding all 3 carbs this weekend. Thanks in advanced for any help. and hello!! i'm new to these forums.
 
so its supposed to stall if carburetor cleaner is added? I new to working on with them and have no clue. is the reason the top to rev the engine when cleaner is added because they are clogged and the cleaner is just enough to fire the engine? i will be taking them all off and cleaning and rebuilding them this weekend. hiopefully that will fix the problem and i can get back on the water.
 
Note----When you put the motor in gear when on the muffs it really is still in nuetral.-----------The prop just has to wave at the air and the prop does nothing compared to swatting water around !!
 
so im pretty much running on 1 cylinder which is the lower one? and thats not enough power for the engine to run under load. am i right with that thinking?
and cleaning / rebuilding the other 2 carburetors hopeful will fix the problem.

and..when spraying the carburetor cleaner into the to 2 carbs is just firing them for a quick second then it goes back to the lower carburator cylinder working.

is my thinking correct here or no??
 
I would say so !---------And do not run the motor the way it is.------No fuel going into the top carburetors means ---NO OIL ----as well !!
 
sounds good, thanks! we got all 3 carbs off right now soaking we are gonna rebuild them and get them back on. ill let ya know how it goes. thanks for all your help.
 
newbreed said:
I have a 1980 Johnson 70 seahorse i'm having problems with. it runs good with the ear muffs on, i can put it in foward or reverse no problem. but when i put it on the lake or in a barrel of water it bogges down and wont run at all. i have checked compression all 3 cylinders have 130-135 and all 3 have good spark. water pumps out really well with muffs and in water. next on the list is carburetors...tonight me and my dad were messing around with them, before we took them off we had the air intake manifold off so you could see all the carbs on the engine. we had the engine started and he sprayed a tiny bit of carb cleaner in the top one and it reved the engine, he sprayed into the middle one and it reved the engine....but when he sprayed a tiny bit into the lower carburetor the engine died insteantly. so we started with that one took it off cleaned it replaced gaskets and float and what not. we put it back on and it did the same thing . anyone have any ideas why its doing this. or why it dies if we spray a tiny bit of carburetor cleaner into the lower carburetor?? or have any suggestions on what we should be looking for...we are planning on rebuilding all 3 carbs this weekend. Thanks in advanced for any help. and hello!! i'm new to these forums.
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