1973 Evinrude 135 HP stalls under load

[Always Broke]

I?ve had a long time stalling problem with a 1973 135 HP Evinrude, it is slowly getting worse. It will start right up, sit and idle great in neutral and rev right up as soon as I raise the cold start lever but as soon as I put it in gear it stalls, no matter weather it?s cold or warmed up. I keep restarting and putting it back in gear until I can get it to take hold and go. As soon as I can get it off idle it runs great no misses, spits, sputters and has tons of power. I?ve raised the idle speed until the gears would clash with no difference as soon as you put it under load at low RPM it?s like some one shut off the key. I?ve tested compression, spark, timing, fuel pressure, made sure the throttle and ignition timing are synchronized, cleaned the carbs twice (there's no adjustments on them) and couldn?t find anything wrong. Every month or so I would try something different and so far nothing has made a difference, is it possible that I have a leak in the crankcase, would that cause the motor to act this way? I do not see any fuel leaking out but since I run in salt water I keep it protected with WD 40 after every run so it always looks damp. I have access to a smoke machine but was hoping for advice before I go through the trouble to hook it up. Any ideas?

 

[emdsapmgr]

Re: 1973 Evinrude 135 HP stalls under load

The carbs on that engine idle with the butterflys completely closed. At idle, the fuel mixture flows through special idle passageways in the upper carb body. It is not unusual for some fuel to dry up in these small passages over time-either restricting them or closing them completely. When doing a carb overhaul these passages (especially) need to be cleaned out throughly with an aerosol carb cleaner. That's the only thing that will clean them. Once the throttle is advanced slightly, the butterflys open and fuel is fed to the engine through the high speed jets and it may run fine above idle. You need to spray the cleaner through one passage in one carb, then repeat the same passage in the other. Watch the spray coming out and compare the flow rate between both carbs, then go onto the next passageway, etc. Make sure you pull the jets out and visually inspect them.