Evinrude 70 VRO Timing troubles

[Into the Blue]

Well I took the plunge and bought an outboard, stolen recovered (insurance sales but with no serial number) and now I know why it was so cheap. Would really appreciate any ideas on the little problem I seem to have.
When coming off the throttle after a run, so the engine's nice and warm, it has difficulty settling to a reasonable tickover. It'll settle to 2,000 revs then 10 seconds later drop to 1,000. I re-adjust the throttle to bring it up to the required speed, and it then runs too fast.
So tried checking the usual stuff, cleaned the plugs, fuel filter, carb sync but no change. Got out the manual and started looking to what else I can check.
Firstly I find I can't get a stable reading on the ignition timing,(tested with a car type strobe) jumps around from TDC to +10 so fast I can hardly keep up. So from the manual I find that it appears I've may have the wrong Ignition sensor set under the fly wheel. The sensor coil connector plug has only 4 connections whilst the charge coil has only 3 connections - this looks like it's a 85-88 model. Manual says I should get 17ohm resistance from sensor coil and I'm getting 11. This is the reading I should get from a 89-90 model.
Will this really make a difference or am I looking way too deep?

 

[GeneH]

Re: Evinrude 70 VRO Timing troubles

You didn't give a year on the engine but I have a 1990 60 Johnson which is basically the same engine with smaller carburetors. I have posted questions about idle timing on my engine several times and haven't gotten a lot of response. Are you using the correct OMC manual for the link/sinc procedure? All aftermarket manuals are too vague and generalized. Have you tested compression? It needs to be checked for eveness and above 100 PSI. Mine is 125 all cylinders. Maximum advance is the critical setting as far as engine damage. Mine specifies 18 BTDC on the water at 5000 RPM. My idle timing is about 8 ATDC which seems all wrong to me but it will idle at 800 and fairly well so what I am being told is don't worry, it can't hurt anything. The three cylinder engine isn't great at idling but you should be able to get it down to spec of 725 RPM though some people add about 100 to this. All adjustments must be done in the lake. I would go back and verify compression and OMC manual procedure. Aftermarket manuals are junk when it comes to specifics, especially if you have an engine that is unique for some reason. Try these things if you haven't already and get back to us with the results. Good luck!

 

[Into the Blue]

Re: Evinrude 70 VRO Timing troubles

Thanks for the info. I'll have to wait until the weekend to give it a try, I'll post an update when I'm done.
Manual I've got is the Clymer, your right it's really general and crosses over so many models it's sometimes unclear if I'm looking at the correct info.
Guess the real answer lies in getting an engine that'll tickover and "sound" right.
Once again thanks