1990 Johnson 70hp engine warm /will not restart

[kjeo1148]

Hi we bought a 1990 70 hp Johnson. starts up great/ runs great! / Fish 20 mins/ will not restart till completely cold again??? Coil/Thermostat have been suggested?? I am about to haul it 8 hrs to my family in Maine. One boat mechanic in my town and he's in mid 80 s ready to retire. Thanks for any help. Just bought the engine and newly retired so funds are tight. Hoping it's something we can fix. Thanks again!

 

[brodmann]

Old coils break down when they get hot, but usually they cause problems when taking a long ride. My thought is carburetor troubles. When it's cold, you use the choke to start the motor. That sends more fuel/air to the motor to get it started. When it's warm, have you tried choking it to get it started? Does that work? If not, possibly use the high idle lever that usually came with the control box of that era. The lever you can lift up to open the throttle a little. Thermostats should not be an issue. If you decide to go into those carburetors, you'll need to purchase carburetor kits. There are small lead plugs in that carburetor that need to be removed to get to the small idle circuit passages and the kit will include replacement plugs. I had a late 70's Evinrude 70 HP years ago. It was a great motor. Never gave me any trouble at all. Would sit for several months at a time and still crank up without issues. The only thing that killed it was lack of maintenance on my part. It started running hot and I realized that I hadn't changed the water pump in about 10 years! When I went to lower the foot, the crank shaft was locked up tight in the bottom of the motor. In trying to force it out, I busted the mid section all apart. Wish I had more patience and at that time. I'm sure that motor would still be running today.

 

[Crosbyman]

Has suggested on-going maintenance is key to happy boating.

what is the mdl number ?? of your engine

you should do complete check of things on a new to you engine.

incl. gear oil replacement, impeller, check for proper cooling (thermostat)
a carb service is a good investment of your time and if you don't damage the gasket(s) you can probably reuse them. . a minimum a good clean-up is needed of all passages.

lots of utubes to help you and folks here .

critical passages and orifices to inspect and clear of any crud. the small side channel leading to the top (see arrow) allows the fuel to reach the top idle circuit. make certain all is clear . Carb cleaner, air pressure are needed . sometimes a small mono filament line to clear crudded passages or orifices.

 

[Crosbyman]

see old style carb problems on the low speed section where fuel drips down at idle

if yours is not a coil issue to solve .... the carb's LS section needs the top plug taken out with a small drill hole and pick. clean the small drip holes and all passages and reinstall a spare plug from the kit. tap it down gently with a flat punch to seal the rim I seal it with fingernail polish around the edge.

as a qwick test to restart the engine try cooling the coils with a coolant spray to see if the problem clears up. Keyboard spray cans from the Dollar store held upside down will cool things qwickly !

 

[racerone]

Does the tell tale hose fitting come off the side off the block or the top of the block??-----There was a service bulletin in 1994 to move said fitting to the top.----ost people suggest installing a new impeller on a " new to you motor !----At least test the overheat horn.----Post the actual compression test values here.

 

[brodmann]

#4 and 5 on that diagram are lead plugs. They have to be removed to get passages cleaned out good. You'll have to order the carb kits to have replacements for those plugs that were mentioned. I know I already said that, but want to make sure you have everything you need before you get started.

 

[racerone]

Whar ?----Item #2 is a lead shot.----And #4 and #5 are core plugs , those wee aluminum discs.