Topic: 1973 6Hp Evinrude Fisherman hard starting cold

This topic has 75 replies, 9 voices, and was last updated 1 year, 11 months ago by fleetwin.

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November 29, 2020 at 3:45 pm #223923
Tom Bertulli
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I am repairing a 1973 Evinrude Fisherman outboard for an old friend. He purchased it from a tourist camp operation and is on a tight budget. It has had lots of use but is not bumped or abused and overall care has been good. The camp had installed a complete new ignition with new coils, points, condensers, wires and plugs and it still ran like dirt because the mag plate bushing was so worn the points would not stay set. I shimmed all the play out of the mag plate and handle gearset and installed 2 nova II universal ignition chips on a heatsink off the side of the block. Also Installed new upper crank seal. Spark is hot, blue and reliable at all throttle settings. Timing light shows spark fires Exactly above the rightmost timing mark on the mag plate – not Ideal but certainly within tolerances for an old motor. I also replaced the fuel pump and rebuilt the carb with a new float at the recommended level. Choke closes properly. Compression is 98 psi on both cylinders. I have about 5 hours running time on a boat. PROBLEM- Cold starting is very very hard (almost to the point of giving up) with many pulls required and throttle setting almost at full. Once started and warmed at fast idle for 5 minutes it runs like a dream all day and restarts reliably in 4 pulls with the throttle set at about 3/4. Idles down to a fast troll for an hour at a time without a miss. I don’t know what next to try but i can offer some clues. Top plug looks more or less normal. Bottom plug is always black, carbony and heavilly oiled. The motor seems to lack a bit of power at top end, but this may be just because it’s a 6 hp on a big boat. Also it has a slight hollow pop sound at mid RPM range and prefers a slow wind out to full throttle as it sometimes bogs if jammed wide open suddenly. I don’t know this type of motor so I wonder if some of these things are normal for the type or not. Regardless I would like to give it back to the old guy and not cause him to have a heart attack trying to start it! I have 4 Hp of the same era that starts if I just twist the flywheel by hand. Can anyone offer any suggestions??
November 29, 2020 at 6:13 pm #223933
crosbyman
Participant
Canada Member - 2 Years
was the top idle chamber under the silver plug checked out ? when the throttle plate is nearly closed and the engine is choked the first fuel vapors come from the idle chamber fuel drip holes when crankcase sucked air speeds by the small holes .

Did you flush the side idle fuel channel feeding the top of the carb body with carb cleaner and strong air pressure .

low speed needle packing ok

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November 29, 2020 at 9:00 pm #223942
Tom Bertulli
Participant
Thanks for the tip. The only thing I did not do was take out the welsh plug & flush the top chamber. Will try it. PS Could it be a reed or reed plate problem causing the lean top cylinder & rich bottom cylinder?
November 29, 2020 at 10:14 pm #223947
crosbyman
Participant
Canada Member - 2 Years
I would chase one rabbit at a time….

inspect LS needle tip it should poke out in the LS chamber ..do you see it clean the side feeder chanel to the top low speed needle

did you clean the HS and check the fat donut gasket at the bottom of the carb bowl …with the choke closed fuel also gets drawn up the HS post .

in effect you should try to soak the carb to ensure all passages are clean and blown dry .

http://www.leeroysramblings.com/OMC_6hp.htm

btw what’s with that metal aluminum plate and all the wires on the side ???

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- This reply was modified 3 years, 5 months ago by crosbyman.
- This reply was modified 3 years, 5 months ago by crosbyman.
- This reply was modified 3 years, 5 months ago by crosbyman.
November 29, 2020 at 11:41 pm #223955
Tom Bertulli
Participant
I appreciate the help. I will disassemble the carb again next weekend. Thanks.. Re Aluminum plate….. this is the heat sink on which are mounted the two Nova II universal ignition chips, which replace the points & condensers usually found under the flywheel. The wire bundle includes one hot from each coil (blue is top cyl. red is bottom cyl) and (black) ground from mag plate to the heat sink itself. Direct grounding in this manner avoids requiring that the current travel to ground through a greasy mag plate bearing. I am told that when mounted under the flywheel these ignition modules tend to overheat and fail in fairly short order. So far after about 5 hrs running they are performing well and don’t seem to get much hotter than about 90 degrees F at any RPM range, so it looks like the heat sink is doing it’s job. PS I called them Nova II universal ignition chips because that is the most popular brand name for these modules, but they are actually “knock offs” purchased at Princess Auto under the brand name Laser.
November 30, 2020 at 8:38 am #223960
crosbyman
Participant
Canada Member - 2 Years
https://forums.iboats.com/threads/1972-6hp-evinrude-idle-issue.739552/

fyi

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December 4, 2020 at 7:45 am #224194
fleetwin
Participant
US Member - 2 Years
OK, well it looks is as if you addressed what would have been my first suggestion, which is the recoil lock out mechanism that limits the throttle setting when cranking, those pieces appear to be gone…
Looks like new coils were installed, did you set the air gap correctly? You will have weak ignition if the coils are set too far in from the flywheel magnets.
It should start easier than four pulls at 3/4 throttle once warmed up also.
“Hollow popping” at mid range usually indicates a lean condition, do you have the carb/ignition sync set correctly? Is the carb butterfly moving easily and closing fully at idle?
Finally, you mention it seems a little weak power wise, are you sure it is running on both cylinders??? These things will run pretty smoothly on one cylinder, but certainly have no power.
You mention the bottom plug looks messy, I was thinking perhaps the fuel pump diaphragm was leaking fuel into the cylinder, but it is plumbed into the top cylinder, so the top plug would be messy if the fuel pump was messed up.. Please DO NOT disassemble this fuel pump to investigate my theory….You could just run the engine with the fuel hose removed and see if the engine picks up once the fuel is out of the inlet hose. Where do you have the idle needle valve set? Initial setting should be 1.5 turns out from gently seated.
I guess next I would pull the plug wires one at a time while running at higher speeds to see if RPM drops equally.
If the sync checks out OK, then perhaps you might want to pop the idle core plug out of the carb to check for debris or a broken needle tip like others have spoke of.
December 4, 2020 at 11:47 am #224215
Mumbles
Participant
Hard starting when cold? Try opening the idle mixture screw a half turn or so and readjust it as the motor warms up. This will help 90% of the time getting these or any other cranky motor started when cold.
December 4, 2020 at 5:10 pm #224230
billw
Participant
US Member - 2 Years
I like Crosbyman’s idea of the donut gasket that goes around the main nozzle, in the center. If that is not sealing properly, it is real hard for the engine to pull fuel up the center of the carb. Air would leak by, instead. It would also go a long way in explaining the mid range popping, which sounds like a lean situation to me.

Long live American manufacturing!
- This reply was modified 3 years, 5 months ago by billw.
December 4, 2020 at 11:06 pm #224282
Tom Bertulli
Participant
Lots to think about here guys – so thanks a bunch. I’ll start by going over the carb again with particular attention to your suggestions. It will be a first if i find anything amiss because iv’e done these on larger motors for years and never had a problem. Boats are out of the water now so lake tests are scheduled for the spring but the barrel is still in the garage and has not frozen yet. I still would like to know if anyone has ever had reed problems with an OMC and what to look for. Bad reed would be a first for me but sounds like it would tick all the boxes.

To Fleetwin
Will check coil air gap on lower coil. I don’t have any tool for this and have always done it by moving the coil out until is just touches and then backing off a hair. Any better way?
Carb/ign sync is good . I already adjusted the cam on the mag plate to take all slack out of the linkage and the throttle just starts to open when the follower first touches the boss mark on the cam.
Will do a wire off test at full throttle when I get on the boat next, but spark is strong blue and reliable when cranked with the starter rope.
Fuel pump is new and LS needle has extra packing but is not really pointy like others I have seen. I thought a bit blunt might be normal for this motor. It does not look broken and no rings or marks from over tightening are visible on it but??? It’s running best at a about 2.5 turns out. PS I have a 1953 Evinrude Fleetwin of my dads that I will get to one of these days. It was put away in about 1980 but still pulls over nicely.

To Mumbles
I’ll try it after I redo the carb if the problem persists.

To Billw
I’d rather rebuild our OEM stuff with a $40 kit than trust a $10 all new part from China any day !!!

Cheers guys.
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