Over a week, and no replies. Thanks folks. Can't believe all the boat motor mechanics on this forum have no opinion on this.
Oh hell Randy, you know we never did like you
. Seriously, I don't know how I missed this one. Now, before anything, do the basic trouble shooting procedure. Remove the spark plugs.
The s/plugs should be Champion QL77JC4 plugs gapped at either .040 or .030 (original and revised recommended gaps).
Do the plugs all look alike, what do they look like? Are there traces of water on any of them?
Check the compression. What are the psi readings of all cylinders?
With the s/plugs still removed, rig a spark tester whereas you can set a spark gap of 7/16". The spark should jump that gap with a wide strong blue lightning like flame... a real SNAP! Does it. Note that the gap is important!
(
Spark Tester - Home Made)
(J. Reeves)
You can use a medium size philips screwdriver inserted into the spark plug boot spring connector, then hold the screwdriver shank approximately 7/16" away from the block to check the spark or build the following:
A spark tester can be made with a piece of 1x4 or 1x6, drive a few finishing nails through it, then bend the pointed ends at a right angle. You can then adjust the gap by simply twisting the nail(s). Solder a spark plug wire to one which you can connect to the spark plug boots, and a ground wire of some kind to the other to connect to the powerhead somewhere. Use small alligator clips on the other end of the wires to connect to ground and to the spark plug connector that exists inside of the rubber plug boot.
Using the above, one could easily build a spark tester whereas they could connect 2, 4, 6, or 8 cylinders all at one time. The ground nail being straight up, the others being bent, aimed at the ground nail. A typical 4 cylinder tester follows:
..........X1..........X2
.................X..(grd)
..........X3..........X4
Bogs down.... when? When throttle is applied, going to full throttle? What? Describe the problem exactly. As it stands, your explanation could mean the engine is bogging when throttle is applied, or missing on a cylinder constantly but cutting in occassionally, sort of a up in the air thing.
If the compression and spark is as it should be, the usual cause is clogged high speed jet(s), a sticking timer base, or the carburetor throttle butterflies are opening too soon.
Let us know what you find.
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