low idle issues, 74, 88 evinrude 15hp and even a merc 7.5

[dkonrai]

i am new to the boards, but have been working on 2 strokes for about 4 years. kinda back yard mechanic only work on my own motors. i have successfully taken motors from the grave to running except for these three motors. i am getting flustered to no end. i hope someone can give a little advice?

three motors, all dont low idle. same symptoms. at low idle they die.

88, evinrude, 15 hp. new hoses, rebuilt carb used all the pieces in the kit, rebuilt fuel pump, compression is 125 in each cylinder. i still need to replace the plastic carb cover to see if this changes the low idle issue. replaced the switch box as well. runs really well from off idle (where u line up the shift arrow) to wot. lots of power full spark and fuel.

74, johnson, 15 hp. new hoses, rebuilt carb used all the pieces in the kit, rebuilt fuel pump, compression is 120/115 in each cylinder. this has points and am waiting for new set of points. i filed the old points and cleaned them with electrical cleaner and finished off with some clean paper. only barrel tested this one. i have spark, and fuel and compression

74, mercury 7.5hp. new hoses, rebuilt carb used all the pieces in the kit, rebuilt fuel pump, compression is 130 in each cylinder.

** i have a brand new tank and hose, glass filter so i can see the fuel and there is no bubbles at the fuel tank. **

arrrggghhhhh all start easy, run, just no slow idle.

dino

 

[Johny25]

Reference to the 88' 15hp...... have you set the slow speed idle screw while the motor is in the water in gear as the manual specifies? Also you may have the idle set to low on your tiller handle. You can raise the idle of your engine right behind the kill switch button by loosening the knob, adjusting it by turning it then tightening after you have raised the idle. Idle should be around 700rpm give or take 50rpm if memory serves me.

The 74' johnson also has the slow speed idle screw on the top of the carb that may need proper adjusting in the water in gear at low idle.. And the idle adjustment is #39,33,38 in the pic below I believe
https://www.boats.net/parts/search/BRP/JOHNSON/1974/15E74S/MOTOR%20COVER/parts.html

As for the Merc...... they make excellent anchors :lol:

 

[dkonrai]

Reference to the 88' 15hp...... have you set the slow speed idle screw while the motor is in the water in gear as the manual specifies? Also you may have the idle set to low on your tiller handle. You can raise the idle of your engine right behind the kill switch button by loosening the knob, adjusting it by turning it then tightening after you have raised the idle. Idle should be around 700rpm give or take 50rpm if memory serves me.

The 74' johnson also has the slow speed idle screw on the top of the carb that may need proper adjusting in the water in gear at low idle.. And the idle adjustment is #39,33,38 in the pic below I believe
https://www.boats.net/parts/search/BRP/JOHNSON/1974/15E74S/MOTOR%20COVER/parts.html

As for the Merc...... they make excellent anchors :lol:

the 88 was run at 7000 feet and we could not get it to slow idle. have read that it could be the stupid plastic cover on the carb. any time i would idle down lower than the shift mark on the tiller the motor would just die. i also had the same prob here at sea level. i live in the bayarea, norcal.

the 74, yes acts the same. here is the link for a video

https://www.youtube.com/watch?v=OlAzbODqZ08&list=UUfiTmKelbegl699wIgknLaQ&index=1&feature=plcp

as for that black anchor, it actually runs good, just wont idle either i have a classic 50, 45hp two stroke that runs like a banshee

 

[dkonrai]

update turns out the 88 had a bad plastic cover. replaced the cover and now it runs great. i frankenstein the carb cover. a replacement would have run over 100. i got a 1992 cover, needle valve, gasket, and o ring. cost was less than half.