Outboard stalls when idling

[usmcveteran]

Ok so it's starting to get really annoying.

Unless I'm crazy it seems to idle better in reverse then in gear or neutral. I was trying to take boat out by driving onto trailer but engine kept stalling at most inopportune times.

How do I trouble shoot the problem? Should I just adjust the idle?

Oh and this is for a 25hp Evinrude with center console.

[usmcveteran]

Couple other things I noticed is that it idles fine when cold and issues start after engine warms up. Using choke seems to help a little bit too.

[24Pink14Stink]

Adjust/clean carb and or spark arrestor if present. Also... check spark plugs gap, air filter and fuel filter.

[usmcveteran]

I did use a ton of Seafoam last year but not sure if it helped. It was worse but I did replace gas tank as well and things got better but still stalls. I think I'll use more Seafoam and check plugs before I take it out next time.

[thughes]

Assuming everything is mechanically sound with the motor (good compression, no air leaks, etc.), it sounds as though you can adjust the idle mixture a little bit, I would guess that it is currently a bit lean. When it stalls at idle does it tend to just trail off and quit or does it "pop" or "sneeze" right before it quits? Using the choke richens the mix up and helps with a lean idle symptom. Going in reverse, the water tends to flood the exhaust idle relief ports (the exhaust holes above the water) which will impede exhaust flow at low speed and cause a rich condition (again, compensating for the lean idle mix).

Do not adjust anything until the engine is good and hot. There should be an idle mix adjustment screw on the carb, in a hole directly above the throat. First you need to know what the current adjustment is, so with the engine off count the number of turns it takes to gently bottom the adjustment screw and write that down. Back it out to where it was and then you have a reference of where it was originally if you totally screw up the adjustment.

With the boat in the water (not on a hose), motor good and hot, idling, IN FORWARD GEAR, slowly turn the screw out (counterclockwise) an 1/8 of a turn and wait 30 seconds for the mix to stabilize. If you continue to go out 1/8 at a time but it never gets better and eventually stalls, run the screw back to where it was originally and do the same process only turning the screw in (clockwise) an 1/8 turn at a time. If adjusting it either way does not provide satisfactory results, return the adjustment to the original position and look elsewhere for the solution.

[camper4lyfe]

Assuming everything is mechanically sound with the motor (good compression, no air leaks, etc.), it sounds as though you can adjust the idle mixture a little bit, I would guess that it is currently a bit lean. When it stalls at idle does it tend to just trail off and quit or does it "pop" or "sneeze" right before it quits? Using the choke richens the mix up and helps with a lean idle symptom. Going in reverse, the water tends to flood the exhaust idle relief ports (the exhaust holes above the water) which will impede exhaust flow at low speed and cause a rich condition (again, compensating for the lean idle mix).

Do not adjust anything until the engine is good and hot. There should be an idle mix adjustment screw on the carb, in a hole directly above the throat. First you need to know what the current adjustment is, so with the engine off count the number of turns it takes to gently bottom the adjustment screw and write that down. Back it out to where it was and then you have a reference of where it was originally if you totally screw up the adjustment.

With the boat in the water (not on a hose), motor good and hot, idling, IN FORWARD GEAR, slowly turn the screw out (counterclockwise) an 1/8 of a turn and wait 30 seconds for the mix to stabilize. If you continue to go out 1/8 at a time but it never gets better and eventually stalls, run the screw back to where it was originally and do the same process only turning the screw in (clockwise) an 1/8 turn at a time. If adjusting it either way does not provide satisfactory results, return the adjustment to the original position and look elsewhere for the solution.

I was hoping you'd chime in on this one. You explain it way better than I ever could pretend to.

[usmcveteran]

Assuming everything is mechanically sound with the motor (good compression, no air leaks, etc.), it sounds as though you can adjust the idle mixture a little bit, I would guess that it is currently a bit lean. When it stalls at idle does it tend to just trail off and quit or does it "pop" or "sneeze" right before it quits? Using the choke richens the mix up and helps with a lean idle symptom. Going in reverse, the water tends to flood the exhaust idle relief ports (the exhaust holes above the water) which will impede exhaust flow at low speed and cause a rich condition (again, compensating for the lean idle mix).

Do not adjust anything until the engine is good and hot. There should be an idle mix adjustment screw on the carb, in a hole directly above the throat. First you need to know what the current adjustment is, so with the engine off count the number of turns it takes to gently bottom the adjustment screw and write that down. Back it out to where it was and then you have a reference of where it was originally if you totally screw up the adjustment.

With the boat in the water (not on a hose), motor good and hot, idling, IN FORWARD GEAR, slowly turn the screw out (counterclockwise) an 1/8 of a turn and wait 30 seconds for the mix to stabilize. If you continue to go out 1/8 at a time but it never gets better and eventually stalls, run the screw back to where it was originally and do the same process only turning the screw in (clockwise) an 1/8 turn at a time. If adjusting it either way does not provide satisfactory results, return the adjustment to the original position and look elsewhere for the solution.

It trails off and quits. I will definitely try this this weekend.

[usmcveteran]

What is idle stop? Could this be issue?

[thughes]

Idle stop (idle speed) should be controlled by idle stop adj screw (not the same as idle mix adjustment) on throttle linkage under motor hood. I believe that idle stop adj on the control box is simply an adjustment to stop the motion of the control lever when the linkage at the motor end is against the idle stop (thereby preventing further travel at the control box end that could over-stress the linkage on the motor end).

[usmcveteran]

Ok thank you for that explanation

[usmcveteran]

So I tried to adjust idle mixture last weekend. I ran boat wide open for a few minutes to warm up engine then I slowed down as much as I could to keep engine going.

I tried turning screw counterclockwise a small amount at a time and didn't notice any difference. Eventually in that direction is seemed like I could smell oil . I then tried the other way a little and no change either.

It was harder to restart engine after making the adjustments. Currently I set it back to where it was originally which was 1.25 turns out from seated. Maybe I do need to clean the carburetor.