This is a tricky one.

[James R]

1984 150 GT Johnson.
Spark was intermittent on #5 and then disappeared altogether during checks. This is usually symptomatic of a power pack failure. Replaced the pack with a new one and still the same. Switching the orange wires leads me to believe I have two faults a bad coil on #5 and something else which is killing the spark for me. The brown wires resistance tests show good. However the timer base resistances on both sides are all 11 ohms. CDI calls for 38-42 ohms. If all the windings are down why is it that I have 5 out of 6 sparks.
Help needed on this one.

 

[Faztbullet]

Re: This is a tricky one.

Put the old pack back on an swap new pack to opposite bank as a bad bias can cause this....

 

[James R]

Re: This is a tricky one.

Thanks Faztbullet, I will try that tomorrow.

 

[multimech]

Re: This is a tricky one.

Is this a run problem or a test problem? A test can give false results if you have leakage on your secondary wire. It is an 84, so I wonder if you dont have wires breaking down arcing to the block or engine cover metal bits.

Either you got unlucky and had a new pack with exactly the same problem as the old one, or the problem is in a connector (non pack side) , a chafed wire or a coil, trigger or stator. These packs have a ground and inputs from the stator and trigger independent of the other pack. They have outputs to the coils.

 

[James R]

Re: This is a tricky one.

The original problem was that it would idle but miss a beat. The tests showed that the #5 spark was intermittent and then disappeared altogether. The new CDI pack did not help and switching coils produced two sparks missing.
In the process I found that one pin was pushed back in the connector on the new pack.
Any way I did what Faztbullet suggested and the new pack worked fine on the port side but the loss of spark still remained on #5.
I had previously switched plug wires which did not tell me anything so I took a spare that I have and tried it. Low and behold the spark came back. I took the original wire apart and the plug connection was badly corroded. I made a new wire and we have sparks on #5. Tested the motor and the idle is still poor skipping a beat every so often. This is not a lean sneeze more like an oil build up or a spark
missing. In consideration of Multimechs info I am tempted to run the motor in the dark to see if the sparks are jumping.

 

[multimech]

Re: This is a tricky one.

Connectors were always a problem with those engines. Look carefully at all of your connections, including the ones that go to the coil wires (if yours have a primary connector on them instead of wire going directly into the coil). Look carefully for any nicks in the harness around sharpish edges. Simply run the thing in the dark with the cover off at the dock or on the trailer and look for any leaks.

 

[James R]

Re: This is a tricky one.

Couldn't run in the dark last night but I pulled the number 5 wire apart and the wire coil on the plug end is badly corroded. Pulled a couple more apart and they are badly corroded also. I will build all new wires. Ran out of the terminal coils so I need more. I see that it is possible to order the coils with the boots but coils only would be enough as the boots are reusable. Any idea where I can get a bunch of coils?

 

[emdsapmgr]

Re: This is a tricky one.

You can purchase the snap-on coil wires in a kit. One per coil. Bombardier part # 582365. You have some minor assembly. These come with a little grease which will prevent air from corroding them in the future.

 

[multimech]

Re: This is a tricky one.

Glad you checked and found those bad connections. On newer coils they did not have orange wire built into them. They had a place where the wire going to the spark plug went on and a place where the orange/with color wire would go on. If yours are the latter, then pull the wire and boot off and see if there is corrosion on those as well. I am guessing there will be if the secondaries are corroded.

 

[James R]

Re: This is a tricky one.

These coils have the built in primary wire. I usually build my own plug wires and have the bulk wire however I have run out of the spiral wound terminals.

 

[James R]

Re: This is a tricky one.

Some improvement but still much the same. All sparks good. Did a fuel spray check again and this time showed #2 lean at idle. Will fix that.
Decided to check the ignition timing. Had to reset the pointer. Running at about 1200 had expected to see 8* or more. TDC mark had not got up to the pointer Same when running the #2 cylinder check, Would have to move the pointer off the mount to get it. Flywheel and key look good and engage correctly. Flywheel pulled down as usual Any thoughts on this guys?

 

[emdsapmgr]

Re: This is a tricky one.

It's good to insure that the idle timing pointer is set correctly. Don't worry about the idle timing degrees. It's only used as an initial starting point after overhaul. You will set the idle timing to the correct degrees for your engine/boat combination when you set the idle rpms. Set the idle to 650-700 rpm's when the boat is floating normally in the lake and it's in forward gear. Idle timing for each/every engine/boat combination is different-depends on how deep the engine sits in the water on your specific boat.

 

[James R]

Re: This is a tricky one.

Not at all very precise from what I can see. I think I will just set the idle with the timing and then make the throttle cam adjustment. Similar to all the rest of these OMC V's.
Thanks EMD....

 

[James R]

Re: This is a tricky one.

Cleaned the top carb again without any significant improvement. Reset the throttles "closed" condition. Slight improvement. No evidence of air leaks.
I have given up on this now and will put up with the slight idle irregularity unless anyone has any other ideas.
Thanks guys for all your help.

 

[emdsapmgr]

Re: This is a tricky one.

An irregular idle is usually a carb issue. The idle jets on these carbs are small and can clog up with dried fuel gel. No way to get it out unless you take the carb apart, pull the jets, visually inspect them and clean them out with an aerosol carb cleaner (like Gumout.) Once that idle jet gets clogged, it can occasionally miss at idle-that's the lean condition. You can't do the cleaning with a fuel additive. Got to pull the carbs apart and disassemble them, including all the jets.

 

[James R]

Re: This is a tricky one.

Of course you are correct. I do take care of business with all carbs. They get stripped and soaked in Gunk carb and parts cleaner, poked to clear any blockage, rinsed in fresh water and blown dry with compressed air. Then they are shot with carb cleaner to ensure that fluid passes through and then put in my heated ultrasonic tank for 30minutes, rinsed and blown dry again. This carb has been done twice now. The only thing I think that would survive that is concrete, but no evidence of that.
Can't think what else to do except replace the carb. If I get a used one I may still have a problem.
Your input is most appreciated.