causes of weak spark & what are the side effects ?

[kknopp01]

motor is a 1989 gt150 johnson
what should the spark look like?

i tested the spark by touching to block and i believe it has weak spark, what could the causes of this be and what does weak spark cause ?

Thanks!

[Joe Reeves]

motor is a 1989 gt150 johnson. What should the spark look like?

I tested the spark by touching to block and i believe it has weak spark, what could the causes of this be and what does weak spark cause?

Spark should jump a 7/16" gap with a strong wide blue lightning flame... a real SNAP! The gap is important! Buy an adjustable spark tester at any auto parts store OR see the end of this reply.

Causes: frayed wires, intermittently shorted ignition switch, stator (under flywheel) melting down due to being overheated, just to name a few.

Results.... erratic running engine, engine hard to start or won't start, might start when cold but after sitting say a half hour or so will not start... think about it.

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(Spark Tester - Home Made)
(J. Reeves)

You can use a medium size philips screwdriver (#2 I believe) 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

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay auction at:

joe_omc32 | eBay
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Now... What is your problem in specific detail?

[kknopp01]

i do have a gap tester, i just grounded them to the block instead, but i used the gap tester and they all jump the gap, have a blue color.... as for sound im not sure all i really hear is the motor turning over

i have a new startor - old done melted down
new ign switch, only had one key and lost it... -_-
coils and coil plugs are all tested and have same values

what is the chance a coil is intermittently bad? just curious

MY ISSUE is that the motor will not idle in the water and requires throttle to stay on, or chokes out. the motor starts to sniffle(what im thinking is a lean sneeze) in the water as well. this lead to me think i was not running on all cylinders, seems to be false. looked for air leaks(b/c of lean sneeze), but really doubt it . weak fuel pump, both are brand new as well as fuel lines. kind of looking at the carbs again , but i just rebuilt them with kits

[Joe Reeves]

Okay... you have another post entered. I think I pretty well answered that question. Can't think of anything new. Your wording of "sniffle" rang the reminder bell.

[kknopp01]

didnt think that got posted! my bad! thank u for the info!