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Jason
Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 15619
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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I have a 1992 40 hp mercury classic out board motor. Im

Customer Question

I have a 1992 40 hp mercury classic out board motor. Im getting spark on all 4 cylinders and still not starting what am I doing wrong? I re did all the carbs, water pump, fuel pump, new fuel lines everything still nothing.
Submitted: 11 months ago.
Category: Boat
Expert:  Jason replied 11 months ago.

Hi Robert, good morning my name I Jason.

Can I start by getting the serial number on the engine so I can run it and see exactly what you have.

Customer: replied 11 months ago.
The serial number is *****
Expert:  Jason replied 11 months ago.

Got it. There is a right way and a whole bunch of wrong ways to check for spark. How exactly did you check for spark?

Customer: replied 11 months ago.
I used a spark tester.
Expert:  Jason replied 11 months ago.

What kind of spark tester did you use? Can you get your hands on a timing light?

Customer: replied 11 months ago.
I don't know what brand of spark test it is I don't remember I bought it from autozone. But I do have a timing light but you can't use a timing light on a motor that isn't starting?
Expert:  Jason replied 11 months ago.

What you want to do is hook up a timing light to each plug wire, one at a time, and then have a helper crank the engine over and see if the light is flashing on all cylinders when the engine cranks over, or if there is no flash. Let me know what happens.

Customer: replied 11 months ago.
Ok we did that all 4 cylinders had a flashing light
Expert:  Jason replied 11 months ago.

Will the engine start on starting fluid if you blast some of that down the carbs?

Customer: replied 11 months ago.
No even spraying starter fluid in the carbs it still doesn't start.
Expert:  Jason replied 11 months ago.

If it's not starting on starting fluid then compression needs to be checked next. Give the compression a test and let me know what the actual numbers are.

Expert:  Jason replied 11 months ago.

Hi Robert, just checking in, any progress or results?

Expert:  Jason replied 11 months ago.

Hi Robert, any progress?

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