1983 35 HP Evinrude Runs Rough

Repair or modification of Boston Whaler boats, their engines, trailers, and gear
rodrig959
Posts: 1
Joined: Tue Jul 31, 2018 3:20 pm

1983 35 HP Evinrude Runs Rough

Postby rodrig959 » Tue Jul 31, 2018 3:27 pm

[The peak reading on a pressure gauge connected to the spark plug port on a dry cold cylinder of a 1983 Evinrude 35-HP and 35-year-old engine is 90-PSI] in both cylinders. I just checked the engine cold after it had been sitting for a few days.

Is [a reading of 90-PSI peak pressure] normal?

[The 35-year-old Evinrude 35-HP two-cylinder outboard engine] had been running rough. I was about to rebuild the carburetors, but now I am concerned that [the cause of the rough running] may be [due to] a bigger problem [than some unspecified problem in the carburetors].

jimh
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Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
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Re: 1983 35 HP Evenrude

Postby jimh » Tue Jul 31, 2018 5:20 pm

There is no specific reading of peak cylinder pressure specified for that 35-year-old 35-HP Evinrude. That both cylinders had the same peak PSI is a good sign. I am not a good judge, but 90-PSI sounds decent to me.

You did not specify what defect or malfunction in the carburetors you intend to remedy by rebuilding them. What do you think may be awry in the carburetors?

I would not abandon the carburetor service on the basis of the peak cylinder pressure you measured.

For some possible insight into assessing the engine, read my article at:

http://continuouswave.com/whaler/refere ... Check.html

My article will offer advice on the proper method to take readings of peak cylinder pressure.