This has been bugging me for years. Looking for ideas.
I've got a 1978 Johnson 70HP that has been puzzling me since I bought it in 2016. On cold start (or warm start after being left alone for 20-30 min) and under initial acceleration the engine often bogs and will stall UNLESS I tap the choke. Then it takes off and runs great. Once it is running great, bringing it back to an idle and taking off again is no problem. This pretty much just happens under load, not at fast idle or on the ears.
Things I've done that haven't made a difference:
One thing I've been tinkering with is having someone else drive and when it bogs, I advance the roller pin (slightly). It takes off. So I added a turn of spacing to the roller pin thinking that might help - nope.
The other thing throwing me off is the willingness to go after a quick choke. And I mean quick.
Other than that very annoying quirk (I can get around but wife and kids struggle with), the engine runs unbelievable.
Any ideas?
I've got a 1978 Johnson 70HP that has been puzzling me since I bought it in 2016. On cold start (or warm start after being left alone for 20-30 min) and under initial acceleration the engine often bogs and will stall UNLESS I tap the choke. Then it takes off and runs great. Once it is running great, bringing it back to an idle and taking off again is no problem. This pretty much just happens under load, not at fast idle or on the ears.
Things I've done that haven't made a difference:
- cleaned carbs (local marina did this when I initially bought the boat because it pretty much didn't run)
- re-sync'd carbs (though I'm about to go do it again from start as I'm learning more about the procedure)
- new fuel pump
- power reeds
One thing I've been tinkering with is having someone else drive and when it bogs, I advance the roller pin (slightly). It takes off. So I added a turn of spacing to the roller pin thinking that might help - nope.
The other thing throwing me off is the willingness to go after a quick choke. And I mean quick.
Other than that very annoying quirk (I can get around but wife and kids struggle with), the engine runs unbelievable.
Any ideas?