Re: 1983 25hp evinrude qwirks ???

Home Forum Ask A Member 1983 25hp evinrude qwirks ??? Re: 1983 25hp evinrude qwirks ???


fleetwin

US Member - 2 Years
Replies: 4737
Topics: 46
#79723
quote outbdnut2:

Dad bought the 1987 35 HP version of that motor new and we ran it on a pontoon boat until 2004. It was very dependable. It had two issues that I take as design flaws.

1. The starting primer function (taking the place of a choke) is an electric actuator that pumps gas into the carb throat when you push inward on the key. Once the motor starts cold, you often had to keep pushing the key in and out to keep on priming for a half minute or so to keep it running at first. I could fix this by adjusting the low speed carb jet richer, but then it was running too rich to idle right when warmed up. I’m not sure what year this priming pump was added.

2. Every 2-stroke outboard seems to have a speed range just above idle where it runs rough as it is transitioning from the low speed carb idle jet to the high speed jet. It is generally a very narrow throttle range. On this series of motors, this rough running speed range is way too wide, including the speed we wanted to loaf the pontoon around the lake at. Several people on this board have confirmed that this is definitely an issue with these motors. On most motors, you can simply increase or decrease throttle slightly to get smooth running at an acceptable speed just above idle – not on these – by the time you increase throttle to get smooth running, you are going way faster. I still see three pontoons on my lake with these motors coming by my dock and hear them running rough as I described. Now if your intended use does not much involve sitting at this speed range, the motor will be great. When it was new, we had it to two different shops under warrantee to correct this issue. One rebuilt the carb – no help, and said they couldn’t make it any better – the other shop said: "That’s the way it is."
Dave

Very accurate criticisms indeed. That stupid electric primer is not easy to operate/understand…People don’t realize that the electric primer is NOT a pump, simply an electric valve. So, if you do not build up fuel pressure first by pumping the fuel bulb, a cold engine will be hard to start.
And yes, you usually had to "tickle" the primer after intial start, which is tricky to do with the key switch. But, the other fault is that these engines are extremely "cold blooded" and require a good deal of warm up before they will run acceptably, just like you say.
The idle and mid range running quality on these engines has never been good. I blame this on the stupid recirculation system that seems to favor one cylinder, making them impossible to dial in a good/smooth idle without an occasional sneeze, you have to leave em a bit rich.
This condition is only amplified when used on pontoon boats where low to mid RPMs are where the engine is mostly used. You could try to alter cam pick up a bit, perhaps a different pitch prop, but this usually only just moves the rough spot to a slightly different RPM…
So, in this case, the OMC tech was giving you "the straight scoop".