johnson 70 stalling, getting ready to light boat on fire please help

desertratz

Seaman Apprentice
Joined
Jul 16, 2017
Messages
49
need your help guys...

i have a 1989 johnson 70 tj70tlcem
Vro was eliminated and i am now premixing
boat will run well at home in a barrel of water but when i take it to the lake it starts up great runs good for about 5 minutes or so then bogs and eventually stalls.
i can get it started again if i accelerate the engine and hit the choke at the same time. i can rev it up in neutral fine but will stall if put in gear. i can sometime kind of power through it and get it to go. also when it starts bogging if i hit the choke it kills it right away and the primer bulb is hard so it is not a lack of fuel.

it is kinda pooling oil/gas in the air cover and and the carbs are slightly spitting fuel. not sure if this is related but this is what has been done so far...

rebuild carbs, new plugs, new fuel pump, all new fuel lines, compression even about 110 psi, i pulled the reed valves last night to see if they were bad but there is a little light visible through some of them but nothing major none are broken or wide open.

im suspecting a bad electrical component at warm up? the weird thing is that it will still start up. i have no idea anyone have any ideas what direction to go in?
 

flyingscott

Fleet Admiral
Joined
Apr 8, 2014
Messages
8,152
You need to do a spark test sounds like it is not running on all 3 cylinders. Revving it at home means nothing. Is the water pump working.
 
Last edited:

desertratz

Seaman Apprentice
Joined
Jul 16, 2017
Messages
49
it has a new water pump and steady stream out the indicator, i did use a spark tester but it is the bulb type all 3 seemed to be firing. spark was weak at first due to loose ground on the CDI box,
 

xjdriver

Petty Officer 1st Class
Joined
Sep 10, 2012
Messages
341
do a spark test like flyingsott suggests, then you need to get it to act up and check for spark on all 3, I used a timing light couse you dont have to disconnect wires, if the light dont flash, you got no spark. powerpack and coils can act up intermittantly.
 

desertratz

Seaman Apprentice
Joined
Jul 16, 2017
Messages
49
thanks guys, i will try the spark test once i get it put back together just ordered the intake gasket.
on a positive note i ohmed the coils and they check out. and best of all i figured out why there is a mess of oil on the front cover. the reed plate has a nipple at the bottom where the oil from the air cover drains and it was plugged up so no way the oil could drain back into the engine.
 

EchoNovember

Petty Officer 1st Class
Joined
May 25, 2017
Messages
315
Do the carbs spit fuel after the rebuild? If so, did you check the float needle valve?

Otherwise, puncture a hole in the gas can, throw a match, walk away. (not real advice, don't do that)
 

desertratz

Seaman Apprentice
Joined
Jul 16, 2017
Messages
49
the carbs will once in a while throw a drop of fuel out, the floats are set correctly and the needles close when full i pressure tested them when i assembled them. trust me sometimes i feel like lighting this boat on fire. but it would always bother me if i cant figure out whats wrong with it so i must push on.
 

desertratz

Seaman Apprentice
Joined
Jul 16, 2017
Messages
49
Ok so, I pulled the flywheel because I have been suspecting ignition components. The timer base looks weird almost melted? What do you guys think
 

desertratz

Seaman Apprentice
Joined
Jul 16, 2017
Messages
49
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