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Jason
Jason, Marine Mechanic
Category: Marine Electronics
Satisfied Customers: 506
Experience:  Degree in Marine Technology, Also Certified with Mercury Marine, MCM, MIE, VP, Yamaha, Honda, Suzuki
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I have a 1988 Yamaha outboard motor, 30 hp , Model 30ELG ,

Customer Question

I have a 1988 Yamaha outboard motor, 30 hp , Model 30ELG , Premium Blend which is not running good. It bogs and it will not idle . I have changed fuel filter it is getting enough fuel and I used fresh high test gas. It seems the top cylinder to be running fine. When you start up the engine and it is not warmed up yet, I pull off the bottom and center cylinder spark plug wires and it doesn't seem to make any difference to the way it runs. When the engine warms up 2 or 3 minutes and now I pull off the bottom and center spark plug wire it makes a slight difference. I put back all three spark plug wires and pull of center cylinder it does not make any difference what so ever. I have removed all three coils, make sure that ground connection is clean, changed spark plugs. The coils all seem to be firing because I used a fourth new spark plug and held it to a proper ground and it seems to have spark. But I don't know if the spark is strong enough or does the coil loose strength. Even when I rev it right up it runs with a very bad miss and has very little power. The engine is clean and not miss used. I don't know what else I can do.
Submitted: 6 months ago.
Category: Marine Electronics
Expert:  Tan replied 6 months ago.

Hello. My name is Tan.

Swap the top coil that is firing good to one of the other cylinders. This way you know the coil is good. If the cylinder you moved the coil to fires now and the coil you removed from that cylinder doesn't fire the top cylinder then you know the coil is bad.

If the top coil still fires we can eliminate the coils as the problem. Now since it fires the plug we could just have a weak stator or bad cdi module.

Customer: replied 6 months ago.
I did do this and it still ran the same way. So you are suggesting that it may not be the coil then. What is the stator. I know what the cdi module is. Is there any way to test this?
Expert:  Tan replied 6 months ago.

Did the coil from the other cylinder fire the top cylinder?

Since we have spark on one cylinder so we can rule out the stator. Leaving the sensor coils and the CDI module.

We can test the sensor coils. Do you have an ohm meter?

Customer: replied 6 months ago.
I BELIEVE WE DO . WHAT DO WE DO TO TEST WITH THE OHM METER.
Expert:  Tan replied 6 months ago.

Disconnect the wires from the cdi module. We want to test between the black to white/red, black to white/green, black to white/black. You should have 310-390 ohms.

These are the wires coming from under the flywheel.

Customer: replied 6 months ago.
OK I WILL DO THIS BUT IT IS ALMOST 11:00 O'CLOCK SO I WILL HAVE TO DO THIS TOMORROW . CAN I CONTINUE THIS CONVERSATION TOMORROW. LET ME KNOW HOW I CAN CONTACT YOU . I WILL CALL YOU BY PHONE EVEN IF WANT TO LATER TOMORROW ABOUT 5 OR 6 PM MY TIME. WE ARE EASTERN STANDARD TIME, WHERE ARE YOU FROM , GIVE ME YOU PHONE NUMBER AND I WILL CALL YOU AT WHAT EVER TIME YOU WOULD LIKE. THANKS
Expert:  Tan replied 6 months ago.

That's fine. I'm on PST so you can contact me the same way you have been.

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