175 Johnson PLEES issue

[Nasonshine]

I have a 1999 175 Johnson plees outboard, I am the 2nd owner- engine has around 300hrs and previous owner kept in immaculate condition.

Engine cranks up just fine at the dock (saltwater) and idles perfectly- would idle perfectly all the way through 20 gallons of gas if l let it- but say I leave the dock and run a few miles to a fishing location, turn the engine off and use trolling motor for 30 min…when I try to restart the engine to run to another fishing spot sometimes it will have trouble starting- or start and the idle is then lower rpms (below 900) and will “sneeze” off. Or sometimes I have to open throttle all the way to get it to restart as if it’s flooded? But again on the first run from the dock out to the ocean it runs perfect, it’s only after I turn the engine off after that first run things start to get weird. But the following day if I go fishing she cranks right up at the dock and idles just fine as if it sorted things out on its own overnight

I rebuilt the carbs spring of 2023, and was having this same issue last fall- put the boat back in the water this 2024 spring with no adjustments and it has run fine all summer until now it’s starting to do this again- any thoughts/help greatly appreciated.

 

[racerone]

What is your restart procedure after the 30 minutes?

 

[Nasonshine]

Typically just turn the key without the push in prime…and it usually starts but then I have to advance the throttle a bit in neutral to get the rpm’s up to around 1100 to keep it from stalling

 

[Chris1956]

Those motors tend to do that. Check your thermostats, as I believe it is made worse by a warmer engine.

The work-around is to start and run them on fast idle for a few minutes, until they run "Cleanly". They should then work OK.

 

[racerone]

Try squeezing primer bulb to fill carburetors before restarting.

 

[Nasonshine]

Thank you for the replies, another example

Say I leave the dock head to the ocean and sight cast for Spanish mack for a few hours- never turning the engine off just bouncing it between neutral and forward keeping up with the fish- the engine does just fine…turn engine off and just drift, turn engine back on after 30 min and gives me trouble on restart/poor idle- run back in a few miles to the dock but once back at the dock she’s idling perfectly again

 

[Chris1956]

Yes, that is what those family of engines tend to do. Let them sit for 2 hours and they are fine. Let them sit for 5 minutes and they are fine. Most think it is heatsoak.

 

[saltchuckmatt]

Float bowls not shutting off completely.

 

[racerone]

???----6 carburetors with the same issue is doubtful.

 

[saltchuckmatt]

Need all six to leak to have a problem? Huh.

 

[Nasonshine]

So maybe check the carb bowl floats and see if they might need to be “bent” or manipulated so they are sitting more flush with the carb? Like the floats are sitting too upward?

 

[saltchuckmatt]

Yes, or the needles themselves or seats.

What brand of carb parts did you buy....did you change everything?

 

[Nasonshine]

Thank you for the replies,
Johnson carb kit replacements for all 6- but I did not bend or mess with the float “positions”

None of the plastic carb bowls seemed to be warped as I have read the plastic bowls can cause leaks over time - not sure if that would play a role in this situation or not…

 

[saltchuckmatt]

Thank you for the replies,
Johnson carb kit replacements for all 6- but I did not bend or mess with the float “positions”

None of the plastic carb bowls seemed to be warped as I have read the plastic bowls can cause leaks over time - not sure if that would play a role in this situation or not…

Plastic parts anywhere on the carb and any imperfect procedure installing them can wreck havoc.

Not the finest piece of engineering.

 

[Chris1956]

Gee, not a nibble on checking the thermostats?

 

[Nasonshine]

Gee, not a nibble on checking the thermostats?

Will take a look at them as well thanks Chris