First post here, though I have lurked the board for a few weeks.
So I ended up with a free boat with a 1975 Evinrude 75 hp "hustler" engine. I am somewhat familiar with working on just about anything, and have some outboard experience, but this one is proving to be a bit of a bear.
Had not been run in at least five years, so I started off with the lower unit and replaced the waterpump with a heavy duty OMC kit, and changed the lube, which actually looked pretty good for old lube. Compression test was fine with all three within 5% around 130 each (seems high, maybe my gauge is off).
Engine started right up with a good prime and a touch of choke, which surprised me after sitting so long. Seemed to run a little rough at idle, but not too bad, so off to the lake with a fresh tank of 50:1.
Would only run up to around 2200 rpm on the tach, and definitely did not seem to be up on all three cylinders. Took her back home after a half hour of towing the kids on the tube at a blazing 10 or so mph. Good thing they are young, and don't really care about the boat being up on plane, or being passed by canoers with trolling motors.
Tried the pumping the bulb test while at WOT to no avail for any increase in rpm/power.
At home, I figure a carb cleaning/rebuild is in order, so an overnight soak and 2 assembly hours later, with 60 bucks in gasket kits and all new fuel hoses, and she's back together again. The float valves were obviously worn, and each carb had it's share of varnish inside, most notably the lower carb which had the high speed jet completely plugged. Cleaned the screen in the pump/filter housing as well of course (barely any gunk in there).
I figure I have replaced everything on the fuel side, so why not check the spark side?
# 1 and 2 have great 7/16ths blue spark, #3, not so much. Nothing. Changed the wires around on the power pack, and when #1 is hooked to the #3 position, it works fine. Same for #2. #3 coil, when hooked to #2 or #1 position on the pack, still nothing. No spark. So I figure the coil is bad. Checked resistance on the primary and secondary sides, and they are all in spec. Compared the resistances on #1 and #2 and they are the same as the non-functional #3. Am I missing something?
I have not gone through all of the checks for the timing and the stator, but do I need to? The power pack has good output to all 3 terminals if hooked up to coils #1 or #2, and generates excellent spark. I just find it hard to believe that #3 (the dead one) can have a set of resistance measurements that are in spec, and identical to the two working coils, but still fire no spark.
Any thoughts before I order a new coil? Can you explain how this could happen in theory?
Thanks in advance for any replies!
So I ended up with a free boat with a 1975 Evinrude 75 hp "hustler" engine. I am somewhat familiar with working on just about anything, and have some outboard experience, but this one is proving to be a bit of a bear.
Had not been run in at least five years, so I started off with the lower unit and replaced the waterpump with a heavy duty OMC kit, and changed the lube, which actually looked pretty good for old lube. Compression test was fine with all three within 5% around 130 each (seems high, maybe my gauge is off).
Engine started right up with a good prime and a touch of choke, which surprised me after sitting so long. Seemed to run a little rough at idle, but not too bad, so off to the lake with a fresh tank of 50:1.
Would only run up to around 2200 rpm on the tach, and definitely did not seem to be up on all three cylinders. Took her back home after a half hour of towing the kids on the tube at a blazing 10 or so mph. Good thing they are young, and don't really care about the boat being up on plane, or being passed by canoers with trolling motors.
Tried the pumping the bulb test while at WOT to no avail for any increase in rpm/power.At home, I figure a carb cleaning/rebuild is in order, so an overnight soak and 2 assembly hours later, with 60 bucks in gasket kits and all new fuel hoses, and she's back together again. The float valves were obviously worn, and each carb had it's share of varnish inside, most notably the lower carb which had the high speed jet completely plugged. Cleaned the screen in the pump/filter housing as well of course (barely any gunk in there).
I figure I have replaced everything on the fuel side, so why not check the spark side?
# 1 and 2 have great 7/16ths blue spark, #3, not so much. Nothing. Changed the wires around on the power pack, and when #1 is hooked to the #3 position, it works fine. Same for #2. #3 coil, when hooked to #2 or #1 position on the pack, still nothing. No spark. So I figure the coil is bad. Checked resistance on the primary and secondary sides, and they are all in spec. Compared the resistances on #1 and #2 and they are the same as the non-functional #3. Am I missing something?
I have not gone through all of the checks for the timing and the stator, but do I need to? The power pack has good output to all 3 terminals if hooked up to coils #1 or #2, and generates excellent spark. I just find it hard to believe that #3 (the dead one) can have a set of resistance measurements that are in spec, and identical to the two working coils, but still fire no spark.
Any thoughts before I order a new coil? Can you explain how this could happen in theory?
Thanks in advance for any replies!
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