1983 70 hp Mariner Problem

S

Smitshaw

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May 19, 2012
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Hi, I am new to the forum site and would like to know if someone can help me out..

I recently bought a 1983 70 hp Mariner; it starts and idles really well, but the moment i put it in the water it has all sorts of problems. As i start to throttle up it sounds like it is starving and i cant get it to rev up at all it just sputters and eventually dies. I am going to do a compression test to ensure that the rings are OK.

does anyone have any ideas.

Regards
 
C

CharlieB

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Apr 10, 2007
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5,617
Re: 1983 70 hp Mariner Problem

Also check for a hot blue spark accross a 7/16 inch gap on each cyl.

Once you verify both compression and ignition then you may find a problem as a lean idle mixture caused by dirty carbs.
 
ajgraz

ajgraz

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Re: 1983 70 hp Mariner Problem

^^^ totally agreed. If you can confirm compression and spark, then you are going to be doing some serious forensics into the carbs and the rest of the fuel system, then doing a link n' sync.
 
S

Smitshaw

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Re: 1983 70 hp Mariner Problem

Thank you for the suggestions, I am going to do the compression test as soon as i get a new tester. and the spark will be next.

Well it has been standing for a while so it might be the Carbs after all.
 
S

Smitshaw

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Re: 1983 70 hp Mariner Problem

Well just done a compression test and found the following

top cylinder 110 psi
middle Cylinder 145 psi
bottom Cylinder 125 psi

What i want to know because there is such a big difference should i open it up and have a look at the rings?

Any help would be great....
 
C

CharlieB

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5,617
Re: 1983 70 hp Mariner Problem

Repeat the compression test to verify the numbers, 145 is a bit high, unless that cyl has a large carbon accumulation.

110 to 125 is a more normal range

You are hoping to find all cyls all within less than 10% of each other.

Variations in throttle opening, cranking speed, and compression tester seal can cause wide differences. A screw in gauge is far superior to a rubber tipped gauge that is simply held into the plug hole.
 
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