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johnson 135 1973 fuel problem

S

Scotty Rankin

New member
motor run fine for about a hour then started acting like it was running out of fuel spiting an sputting check the fuel line bulb it was soft tried to pump it up did get very hard . The motor acts like it not open all the way up i thought might be throttle ajustment could it not be getting enough fuel ? new to the boating scene so this might sound dumb just looking for info thanks
 
Remove s/plugs, check compression... what are the compression readings?

S/Plugs still removed, check for spark that should jump a 7/16" gap on all cylinders. Does it?

Remove drain screw from carburetor float chamber to check fuel. Does fuel exist there? Is there water in the fuel?
 
to check the compression just take out splugs an put gauge on an turn motor over ??? do you take out all the plugs or one at a time to do this and what the proper spark plug gap ? what exactly do you mean by jumping a 7/16 gap ? thanks
 
The manufacturer engineered and built ( at some expense ) an ignition system that could and should jump a gap of 1/2 " because outboards need a good ignition system !!!!--------------With a 1 foot piece of spark plug wire an alligator clip and a piece of plywood you could make a simple tester.--Cut the wire in half and staple it to the plywood with a 7/16" gap between the ends.----------Stick one end into the motor plug wire and the alligator clip on the other end to the block.
 
put new plugs and a new fuel line on . run motor on muffs seemed to be running ok but the compression is low ithink 55 on 3 of the cylinders 40 on the #1 cylinder . I there anyway to get compression up whitout a complete rebuild ? Thanks for all the help !!!
 
If the engine is turning over slow, the compression reading will be low. The engine must turn over fast, at 300 rpm or better. Have "all" spark plugs removed when checking compression.

S/Plugs still removed, check for spark that should jump a 7/16" gap on all cylinders. Does it? This means that you DO NOT want to test for spark simply by using the spark plug(s) which is a waste of time. If the spark will not jump a 7/16" gap with a strong blue lightning like flame... a real SNAP, then there is an ignition problem. The engine must be turning over at least 300 rpms during this test and have "all" of the spark plugs removed..

What do I mean by a 7/16" gap? The spark plug gap is .030.... you need a tester that you can set to various gaps, 7/16" in this case, to test the spark. No tester? See the following:

Spark Tester - Home Made)(J. Reeves)
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
 
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