1976 Johnson Evinrude 55 HP speed issue...

dstack

Recruit
Joined
May 13, 2012
Messages
1
Hello all. I have a 1976 Johnson Evinrude 55 HP motor and it has been giving me some problems.

Main Problem: Some Times while running at full speed it drops down to only about 2-3 knots. When this happens I start to pull the throttel back towards the middel and the the motor kinda sounds like im running on fumes, with little hops of exceleration. Once this happens I basically have to power.

Symptoms/Observations:Iv'e noticed on a full gas tank (25L) i can run at full throttel I suppose I get up to about 20-25 knots, but it seems like when ever I get down to about half tank this is where the loss occurs and the miles to literis AWFULL. I have also noticed (with the gas tank is about half full) I pump the ball -1 I can hear a psst somewhere near the feul filter/pump (is that normal?) and the ball doesn't get hard (shouldn't it?) The connector to the top spark plug seems a little lose,so I tried to clamp the connector so it sits better.

Whats been done so far: So far The carbs have been taken apart and cleaned. New gas tank (buying a new pump ball today). Inspected gas filter (seemd ok) Added a new metal clam to the gas hose on the rear side of the connecting clip that goes up to the filter/pump. The starter was repaired (the 2 pads where burned and like 3 wires had to be set back into place and soldered.

I think thats about it. I'm new to boating and I just bought this boat cause I have family coming for vacation in July and I would really have this fullyfunctioning befor then. Thanks in advance for any trouble shooting tips or suggestions.

Regards
D.
 

willib0731

Cadet
Joined
Aug 8, 2012
Messages
14
Re: 1976 Johnson Evinrude 55 HP speed issue...

If the bulb doesm't get or stay hard and you have a hissing sound when you wqueeze it you have a leak in the fuel line or the pump. It may only be noticable at half a tank or less because the pump is working harder at those levels. Do you have the vent open on the tak so it can suck more are into the tank to maintain pressure in the tank?
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: 1976 Johnson Evinrude 55 HP speed issue...

You may have a leaky fuel pump diaphram. This allows fuel into the crankcase and may have trouble pulling fuel out of a half tank.
 
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