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Jason
Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 14295
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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115 bogging at wot

Customer Question

115 Johnson bogging at wot
Submitted: 8 months ago.
Category: Boat
Customer: replied 8 months ago.
I've changed plugs checked spark and compression with my gauge I'm at 132 or 133 across the board carbs have been cleaned and are working properly
Customer: replied 8 months ago.
Motor is a 1999 v4 60° looper
Expert:  Jason replied 8 months ago.

Hi Ryan, my name is ***** ***** I will be helping you today

What kind of RPMS are you getting out of the motor at top speed?

Customer: replied 8 months ago.
About 2200 to 2500
Expert:  Jason replied 8 months ago.

Does it ever get any higher than that?

Customer: replied 8 months ago.
Only in neutral or the muffs
Expert:  Jason replied 8 months ago.

Got it. The next step would be to do a spark output test. Do you have a timing light or adjustable gap spark tester?

Customer: replied 8 months ago.
It jumps a 7/16 air gap on all cylinders it's got great compressionI'm leaning towards the optical eye
Expert:  Jason replied 8 months ago.

The eye either works or it doesn't. If it wasn't working the engine would not start, so that is not it. (the eyes themselves are actually extremely reliable) The engine however can drop spark under a load if the powerpack is bad or if there is a bad coil. The best way to check it would be to hook up a timing light to each plug wire, run the boat at top speed, and then see if the timing light is flashing steadily indicating good spark. Or see if the light is cutting out, indicating the engine dropping spark. Is that something you can do?

Customer: replied 8 months ago.
What type of timing light do I need just a regular one?
Expert:  Jason replied 8 months ago.
Just a regular one is fine. They make them both corded, to hook up to a battery, and cordless, with their own internal batteries. A cordless one would be a little easier to use while out on the water. Click this link below, this is an example of a cordless one http://www.amazon.com/gp/product/B002KS72GA?keywords=self%20powered%20timing%20light&qid=1457962787&ref_=sr_1_1&sr=8-1 What you would want to do first is see if the engine is dropping spark at 2500 rpms. If it is, swap the coils around and see if the lack of spark stays on the same coil or not. If the lack of spark follows the coil, the coil is bad. If the lack of spark stays on the same cylinders, the powerpack is bad. Does that make sense?
Customer: replied 8 months ago.
I was just saying we replaced the optical eye before when it was doing this maybe now the pack is gone I'll check it out and report my findings
Expert:  Jason replied 8 months ago.

Powerpacks fail 20 times more often than the eyes do. Those optical eyes are extremely reliable. Do the spark test under a load, and let me know what happens.

Customer: replied 8 months ago.
I sure will thanks man I'll report back tonight
Expert:  Jason replied 8 months ago.

You are most welcome, keep me posted Ryan.

Thanks,
Jason

Expert:  Jason replied 8 months ago.

Hi Ryan. I didn't hear back from you. Any progress?

Expert:  Jason replied 8 months ago.

Hi Ryan, how are you making out?

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