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After Rebuild Dies at Full Throttle

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palerider

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Pretty excited complete rebuild (carb, rings, electical, etc.) of 6 hp 1968 seahorse - it acutally started. Still have some bugs though. Been running it according to break in outlined in manual. Runs solid until I give full throttle. When full thottle runs for a while then dies suddenly. Then starts righ up. What do you think? Any adice would be apprecaited. thanks
 
All fuel components (bulb, cap, suction) are fine. I noticed when it would die a puff of smoke would come from carb.

Is the follower cam the piece that that kicks the roller out? Is the mark on it the small ridge on it? Where I'm pointing with pencil? Also I notices that throttle settings run, start, stop, etc. are off. Someone drew a line on throttle to show speed for shift - if the follower cam is not set right would that throw that off? In the picture throttle shows slow and it's not touching the roller yet. I'm surprised it can be that far off. What do you think?

100_0898.jpg
 
The setting marks on that band that's located on the throttle handle is actually just for referrence ie which way is slow/fast, that sort of thing. Ignore it or it'll drive you nuts.

Yes, that's the cam your pencil is pointing at.

The throttle butterfly is to just start opening when that scribe mark on the cam is dead center with the carburetor throttle roller.... not before or after.
 
Thanks. I'm leaning toward it being timing related. When it dies I get a little smoke coming from the carb. At least on cars backfiring thru carb is usually timing. Any tips on checking timing?
 
Hook up a timing light to top cylinder.----Shine the beam at the 2 vertical marks on the magneto plate.-------You should see the timing mark on the flywheel in between the 2 vertical lines.----Repeat with bottom cylinder.
 
Timing is set by the flywheel key.... aligns the magnets with the crankshaft etc. Unless the key is sheared, the engine is in time. If out of time, the engine would not run at all.

However, it's possible you have the points out of adjustment. Reset as follows:

(Point Setting Of Magneto Models)
(J. Reeves)

Set the points as follows. Have the flywheel key aligned with the fiber rubbing portion of the ignition points. Adjust the gap so that a .020 gauge will pass thru but a .022 will not. Should there be any question of the points being dirty (touching the contact with your finger would cause them to be dirty), clean them with a small brush and acetone or lacquer thinner.

NOTE 1: Should the operating cam have a small portion on it with the word "SET" imprinted, align this portion with the fiber rubbing portion instead of the flywheel key.

NOTE 2: Should the cam have the word TOP imbossed on the top of it, that is a cam that could be installed upside down and this is simply telling you which side is up. It is not a position where one would set the points.

You say the engine runs at full throttle awhile then stops..... assuming you still have spark and I'm sure you do as the engine starts back up..... BUT before you attempted to restart, did you pump the fuel primer bulb back up hard? If so, you refilled the carburetor before attempting the restart which would indicate the engine is running out of fuel.

Does pumping the fuel primer bulb constantly, acting as a manual fuel pump make a difference of any kind? If this pumping action cures the problem, that indicates either a failing fuel pump or a bad leakage between the fuel pump and the fuel supply.
 
kimcrwbr1 said:
The primary pickup for that model is #6 you line the mark on the cam to the right side of the follower roller at that point is when you want the throttle butterfly to begin to open. Timing is not adjustable point gap is the adjustment. Unless my book is wrong?
Click to expand...

The later 6hp models (later 1970's up) use the center portion of the roller as per all of the other OMC models that incorporate the roller setup regardless of their year of manufacturer.

However Kim, you are correct in stating that the scribe mark should be aligned with the rounded starboard side of the roller when the butterfly just starts to open on that particular 1968 model.... according to the manual. This allows the throttle butterfly to be open ever so slightly so as to have the idle rpms increased somewhat.... a feature needed on some smaller hp models but not all. Thru the years, although aware of that weird setting, I've come to prefer the center of the roller setting as have many other technicians and have encountered no problems.... seems to be a matter of choice. We don't always agree with the book.
 
Points were off a little - regapped and took for spin - did not die out. What kind of powere should I expect out of the motor? Had it on my 14 foot rowboat and really did not move it much. I would be surprised if I got it much over 5mph. Have had a 10 HP and 15 HP both were able to plane it out. Did no expect that much of a a drop off. Was I expecting too much? Probably will sell the motor but want to make sure running as expected before I list it.
 
For reference I have a 89' 6 HP in great condition.
Three boats it was/is used on. Two 12', one heavy and one light.
No problem planing the light one with one or two people.
One person in the heavy one or it will not plane.
1 14' aluminum will not plane unless my 15 year old is the only one in it.
 
Thanks my 14 foot is an old crestliner - pretty solidly built. Hardly pushed it. As mentioned good trolling motor. Even thpough my 15 HP pushes pretty good and planes pretty quickly. Really would like a 20 HP. Now That I got a rebuild under my belt - may look for one to restore.
 
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