1977 Johnson 70 HP Hard start issue

[DMontana]

Hey guys,

Having an issue with the aforementioned motor.
A little history first. I bought this motor off CL to replace a smaller motor which came with my boat. This motor was in good shape and the price was right.
Once I got the motor home, I ordered some parts and here is what I have done:
Rebuilt all 3 carbs (also replacing and carefully setting the floats), rebuilt the fuel pump, replaced the t-stat, replaced all fuel lines (including those from the built in tank to the motor, bulb also), replaced all 3 coils, replaced water pump, replaced plugs, and then I performed the Link n' sync. Also checked spark at all three coils to make sure I had a 7/16" jump.
Now the issue that I am experiencing. The motor starts up and runs great when I first launch the boat, but when I stop for an hour or so to fish or whatever, I have a hard time getting it started again. Not sure whats going on since it started right up after winter storage this year.
I did alot of searching this forum for an answer before posting and it seems there are alot of the same issues, but most had no solutions. Any Ideas of what to check or look for?

Thanks!

 

[boobie]

Re: 1977 Johnson 70 HP Hard start issue

Check your spark again when it quits and won't start.

 

[DMontana]

Re: 1977 Johnson 70 HP Hard start issue

Check your spark again when it quits and won't start.

Will do, Thanks. It will be two weeks before I can get back down to the river, but I will check that.

 

[pn]

Re: 1977 Johnson 70 HP Hard start issue

it could be fuel related too... either float bowls going dry or too much gas flooding the engine. try pumpin the primer bulb to see if the fuel bowl are running dry after you sit.

 

[DMontana]

Re: 1977 Johnson 70 HP Hard start issue

it could be fuel related too... either float bowls going dry or too much gas flooding the engine. try pumpin the primer bulb to see if the fuel bowl are running dry after you sit.

I think you are correct. I have a feeling that one (or more) of my carbs are letting fuel continue to flow while sitting. Unconfirmed at the river, but I tested this by running my motor on muffs in the drive way until it warmed up, fired right up. Then I let it sit for an hour or so and tried starting again. This time had some issues and when it finally did start, the exhaust was covered in fuel/oil.
Two days later I repeated this process again, but this time shutting off the fuel and letting it run almost out before shutting it down. An hour later I turned fuel on, pumped bulb and she fired right up.
Looks like I will be pulling the carbs, but not until the fall.

Thanks