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Dominick
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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1979 mercury 70 hp. Rebuilt the engine with new power head,

Customer Question

1979 mercury 70 hp. Rebuilt the engine with new power head, wiseco pistons new reeds 120psi compression cold. It ran for 1/2 hour then revved up and stalled ( like a 2 stroke running out of gas ) Thought it was the boyesen reeds so replaced them with new stock reeds. Everything looked good in the engine. Put it back on the boat. Still no start, has spark and fuel. What am I missing?
Submitted: 2 years ago.
Category: Boat
Expert:  Jason replied 2 years ago.
Hello my name is ***** ***** I will be helping you today. Will it run on starting fluid?
Customer: replied 2 years ago.
the plugs are wet
Expert:  Jason replied 2 years ago.
????
Expert:  Jason replied 2 years ago.
Do you have any starting fluid you can try?
How specifically did you check for spark?
Customer: replied 2 years ago.
I pulled a plug and grounded it against the head and cranked the engineI will look for some starting fluid.There are 2 vacuum lines on the engine. What do they do? It looks like 1 hose goes from the top of the block to the bottom and the other is in the middle of the block and hooks to a port on the front cover.
Expert:  Jason replied 2 years ago.
Those are oil recirculation lines.
Grounding the plug against the head is not the correct way to check for spark. What you need is an adjustable gap spark tester. Watch this youtube video, it shows the proper way to check for spark. You can fast forward to the 3 minute mark.
https://www.youtube.com/watch?v=eSmNMWTDtZE
Customer: replied 2 years ago.
I will try the spark test. Not sure why the motor revved up just before it died. Usually that means that it was running out of gas. Right? But that makes no sense because the engine is now flooded. Very frustrated that this thing is kicking my but
Expert:  Jason replied 2 years ago.
It usually does. But test spark the correct way, get some starting fluid, and lets see what happens.
Customer: replied 2 years ago.
OK
Customer: replied 2 years ago.
Not very hot spark. Only jumps 1/4'
Expert:  Jason replied 2 years ago.
Alright now we are making progress. Do you have the serial number on the engine handy, I need to see which igniton system you have.

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