1990 Johnson 150 spark problem

[bill9259]

Looking for some help. I have a 1990 150 Johnson I bought used that had a bad cylinder. I rebuilt the powerhead with a freshwater block and bored it 030 over with new pistons. I have the engine all together and was going thru some checks getting everything ready to syart the engine. I had all the new plugs out to check for spark on each cylinder. Cranking the engine over with the starter I have one cylinder with no spark at all. I swapped plug and coil to another cylinder and the plug fires. Seems the spark problem is isolated to this one cylinder. Is this a power pack problem? This engine only has one power pack up on the top of the engine - part# 583816 Have rebuilt carbs so they are clean and have tried to do everything right so as not to hurt my new powerhead. Don't want to start without good blue spark to each cylinder. Any suggestions as to what I should do next?

 

[HighTrim]

Re: 1990 Johnson 150 spark problem

Just to be sure you did not have a loose ground or whatever on the coil, did you use a coil from a known good cylinder on the cylinder in question to see if it now fires?

Do you have a DVM, or better yet, a DVA meter?

 

[bill9259]

Re: 1990 Johnson 150 spark problem

I used a coil from another cylinder that was firing a good blue spark and installed it in my cylinder with no spark and it still did not fire. The coil that was in the cylinder with no spark fired a good blue spark when I moved it to another cylinder. The no spark seems isolated to this one cylinder and it is not a bad coil, spark plug or plug wire. Would it be a voltage problem coming from the wire from the power pack to the coil? I don't want to change a lot of parts for no reason when it seems to now be a definite problem with the firing on this one particular cylinder. I have a digital volt meter. Is their a way to test a power pack or can the problem be with another part like the stator. This is my first real ignition problem with a V6 outboard. Thanks for any suggestions.

 

[HighTrim]

Re: 1990 Johnson 150 spark problem

ok sorry I misunderstood you. The following is taken from the CDI troubleshooting matrix.

NO SPARK ON ONE CYLINDER:

1. Check the timer base?s resistance and output (see chart below).
2. Check the DVA output on the orange wires from the power pack while connected to the ignition coils. You should have a reading of at least 130V or more. If the reading is low on one cylinder, disconnect the orange wire from the ignition coil for that cylinder and reconnect it to a load resistor(another coil). Retest. If the reading is now good, the ignition coil is likely bad. A continued low reading indicates a bad power pack or Timer-Base.

Check the stator and trigger resistance and DVA output as given below for each bank:

Wire Color : Check to Wire Color : Resistance : DVA Reading
Brown wire: Brown/Yellow wire :900-1100 (35 amp) :150V or more Connected
Orange :Orange/Black: 93-103 OEM :12-24V Connected
Orange :Orange/Black :45-55 CDI :12-24V Connected
White wire: Purple wire : (a): 0.6V or more Connected
White wire: Blue wire : (a) :0.6V or more Connected
White wire: Green wire: (a): 0.6V or more Connected
White wire urple wire 2nd connector: (a): 0.6V or more Connected
White wire: Blue wire 2nd connector: (a) :0.6V or more Connected
White wire: Green wire 2nd connector: (a) :0.6V or more Connected
White wire :Black/White wire 2nd connector: 215-225: Not Applicable

(a) Use a comparison reading as different brands of meters will give different readings. The typical range is 1M to 5M ohms. As long as you have approximately the same ohm reading on all six tests and the correct output with the DVA meter, the Timer-Base should be good. The exception would be if one of the scr?s inside the Timer-Base is breaking down while the engine is running. This can be found indexing the flywheel and checking the timing on all cylinders. If the readings are off, reverse the meter leads and retest to see if the readings are corrected.