Re: 1975 Johnson 135 questions
Yes, 20degrees is more than too cold - to have it act up. so don't stress.
The fellas talking about the choke are giving good info..
When choked by the toggle switch, both choke plates must completely close. Close enough is not good enough! It will always be a hard cold starting motor if there are any gaps top/bottom.
You also want the choke plates to fully release/retract otherwise it will run rich. You can also engage the solenoid plunger by hand ensuring nothing is binding and it moves freely. Sometimes the plunger has dried grease, causing binding.
Yours is clearly not closing fully, since the manual choke fires it up quickly. There are adjustments as noted by others and also between each choke plate - one will bottom and the other is slightly not.
Racerone explained how the temp controlled solenoids work from the factory. They were problematic and an OMC service bulletin explained the repair/update.
I have explained this before, but Joe Reeves did it more detail, so I'll quote Joe. An additional fyi, if the small 20 amp fuse blows, it can often be traced to the choke solenoid warm up circuit, which should simply be disconn'd purple/yellow at the terminal strip.
Yours seem ok, so do as follows... It'll take 2 minutes. In cold weather you will need to keep "blipping" the choke closed to keep it running until it warms, with idle speed up.
(Temperature Actuated Choke Solenoid Conversion)
(J. Reeves)
Various OMC engines that were manufactured in the later 1960s thru the early 1970s, for example the 1969 55hp Evinrude/Johnson incorporated a dual stage choke solenoid...... easy to identify as they have two wires leading to the solenoid, one purple/white, one purple/yellow.
The purple/yellow is attached at the engine wiring terminal strip to another purple/yellow wire that led to a heat sensor. The initial stage, with the key ON, (purple/yellow), when cold, would keep the choke pulled in half way until the engine warmed up, at which time it would release and open the choke butterfly.
The second stage (purple/white) is attached to another purple/white wire at the engine terminal strip which leads to the choke switch. When the switch was engaged, the choke closed etc.
The problem with this setup is that as the engine got older, the thermostat acted up, water pump became weak, whatever, the heat sensor failed to operate properly and the choke would not release from that half closed position. This would cause the engine to run in a rich fuel mixture condition (flooding, loading up).
The cure to this problem, via a service bulletin from OMC was to remove the solenoid purple/yellow wire from its original location and connect both of the solenoid wires (purple/yellow & purple/white) to the engine wiring harness purple/white wire at the engine terminal strip.
The above change would allow both solenoid wires to be energized when the choke switch is engaged, pulling the choke butterfly in firmly..... and only when the choke switch is engaged.
Dazk14 Edit: I did not read through the earlier posts. Also, it was quite common for the warmup circuit to load up cylinders (read stop firing), until the cylinder(s) could be aired out by running the boat up on plane (read under load - not revving in neutral).
