1992 Evinrude 140 misfiring pops and dies at idle

[Spenser]

Hi
my 1992 Evinrude 140 misfiring pops and dies at idle
every once in a while there is a slow down and pop like every 10 - 15 seconds
i have rebuilt the carbs, sprayed around them when engine runs - no difference
changed power pack - same behavior
compression is good everywhere
changed plugs - no difference
disconnected kill wire - same problem

for now i disconnected the black/white wire to temp sensor and idle is at 1200 rpm which would cause the engine not to stall in idle often, but still may stall

when boat is moving in water and rpm is above 1000- no stall i guess because the inertia does not let the engine slow down quick enough

i am able to run the boat in water above 4000 rpm - seems ok

i am totally out of ideas now...

1992 Evinrude 140
no VRO (removed a while ago)

 

[jakedaawg]

Sounds like you missed an orifice or two when you cleaned the carbs.

 

[jakedaawg]

There are also passages in the throttle bodies that need to be cleaned. You may also need to check for leaking/warped float bowls if plastic.

 

[Spenser]

There are also passages in the throttle bodies that need to be cleaned. You may also need to check for leaking/warped float bowls if plastic.

i have also adjusted the floats a little because there was a gasket in rebuild kit for metal thing where jet goes, not sure if related

 

[jakedaawg]

i have also adjusted the floats a little because there was a gasket in rebuild kit for metal thing where jet goes, not sure if related

If you're referring to the needle and seat for the float you only use the gasket if there was one there previously...other than that I am not quite sure what you are referring to...

Was the carb kits you installed BRP or were they aftermarket? I personally have never been able to get the Sierra aftermarket kits to work correctly in those loopers.

 

[Spenser]

If you're referring to the needle and seat for the float you only use the gasket if there was one there previously...other than that I am not quite sure what you are referring to...

Was the carb kits you installed BRP or were they aftermarket? I personally have never been able to get the Sierra aftermarket kits to work correctly in those loopers.

yes that is was what i meant the seat for the needle
I have used aftermarket maybe that is the issue...

also is there a procedure i can use to pinpoint the carb issue? or is trial and error the best apporach?

 

[jakedaawg]

Aftermarket would be a 1st guess as to issue.

if you put the gasket for the seat in, AND there was not one originally, that would make that run lean creating the pop. You can not adjust it out with float adjustments.

seems to me, it's been awhile since I've had to do a looper carb:
1. Remove seat.
2. If the area around the threaded hole where the seat screws in already has a raised area machined in you do not use the seat gasket.
3. If that same area doesnt have the raised area you use the seat gasket/washer.
4. Remeber, these kits are for more than one model so extra unused parts is not a concern.

***if you are having a lean pop issue do not run motor to try and figure it out. Running lean is really bad.

 

[jakedaawg]

I will also mention this. Dont take me wrong. You referred to the needle and seat as being a jet. People use jet and orifice interchangeable...I will restate that it sounds like you missed an orifice or two when you cleaned carbs. Not a needle and seat, an orifice/jet. These are little brass things screwed into various holes in the bowl or sometimes body of the carb. Often times they are in a passage only accessed after you have removed the bowl drain screw. You remove them carefully with the appropriate screwdriver. Clean them till you can see through the tiny holes, clean where they go, and put them back in.

The above is just general carb cleaning advice, it applies to many but not every carb on any engines.