72 50 hp Johnson wont turn over...

Freddyb18

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Joined
Nov 2, 2011
Messages
14
72 Johnson Hydro Electric Shift 2cyl

Just got the thing running in the last week or so. I would get it in the water and it would usually fire up first time. If not, a shot of starter fluid would do the trick.

When it has been running, it would idle very well. It started out when the thing was WOT, it would go for about 10-15 sec's and then bog down. I would let off the throttle to keep it going. But, it had no issues at or slightly above idle. Even if it killed itself, it would usually start right back up. I bought it from a guy about a month ago. He said it had been sitting since 2003. The motor looks to have been kept in very well.

Last night I dropped out some jug lines. The motor ran as it typically does, maybe a little more convincing than usual. I dropped out the juglines, and on the way back to the ramp it died on me. I tried to start it again, and it did not want to turn over. I waited for about 15 minutes, and it fired back up. When I got back to the house, I shot some carb cleaner in it with the throttle flaps open.

This morning I went to check/collect the jugs. It was 30 degrees when I hit the water. I sat at the ramp and tried to get it to fire, but to no avail. I spent an hour or so trying. I got it home and drained the bowls on the carbs. I adjusted the throttle lever inside the engine that moves some lever under the flywheel. I also removed the plugs and checked for spark. When I removed the top plug, and tested it, the motor fired. I let it run at idle for a while, buttoned it back up and headed back to the river.

Got back on the river and made it about a mile down and the thing died on me at what normally would have been a "safe" speed. Forgot the D*** trolling motor at home and got to paddle... lol No clue what is going on, I would like to A. get it back to a "running condition", and B. stop this whole bogging down issue.

Things I have replaced since I bought it: Starter Solenoid, Plugs, Gas Lines, Impeller.

I have read a lot about fuel delivery and timing... ANY ADVICE WOULD BE GREATLY APPRECIATED!

Thank you!
 

dazk14

Ensign
Joined
Jul 22, 2008
Messages
966
Re: 72 50 hp Johnson wont turn over...

go through the carbs, before you fry that motor.

Stop screwing around with linkages/timing - you can fry the motor that way as well.

How many wires are going to the choke solenoid? It will be 2 or 3 including the black plus 1 or 2 purple (as I recall).
 

Freddyb18

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Nov 2, 2011
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Re: 72 50 hp Johnson wont turn over...

2 purples are going to the choke solenoid
 

boobie

Supreme Mariner
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Nov 5, 2009
Messages
20,826
Re: 72 50 hp Johnson wont turn over...

If the mtr has been sitting since 2003 the first thing to do is go through the carbs. Before that do a compression and spark test.
 

Freddyb18

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Nov 2, 2011
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Re: 72 50 hp Johnson wont turn over...

In regards to a spark test, I have replaced both spark plugs. I took out the spark plugs one at a time and grounded them to the block, each sparked. Does this qualify for what you are talking about? Is there something more I should have done?

The motor ran pretty solid with the exception of it bogging down. Shouldn't that tell me that the compression is there?

I AM a newbie to boat motors, this is my first. I certainly do not want to sound rude, just asking questions for clarification. Thank you for your reply.
 

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Re: 72 50 hp Johnson wont turn over...

The spark test means having an open air gap spark tester ( purchased at any parts house for $10.00 or less), setting it to a 7/16" open air gap and cranking the mtr over to see if it jumps the gap. Hope this helps.
 

5150abf

Vice Admiral
Joined
Aug 12, 2007
Messages
5,808
Re: 72 50 hp Johnson wont turn over...

DO NOT spray carb cleaner or strating fluid in ti EVER, it cleans all the oil off all the internal parts of the engine and runnig with no oil is very very bad.

I concure, if it isn't running right don't run it, there is something wrong, fix it before you smoke the engine.

It does sound like a carb issue but varify compression numbers, you can get a compression gauge at any auto parts store, numbers should be within 10% on each cylinder, and no, just becuase it runs doesn't mean it has good compression or that the cylinders are equal.

Alot of times when you change gas line you will get small bits of old hose that clog the carb or fuel pump.
\
Look up Linc and Synk since you moved stuff you need to get it back where it was, the throttle and timing are linked on an outboard, if one is off just the slightest bit at best the engine won't run riight, worse case it burns up, and once you set them there is no reason ever to adjust them.

Get a factory OEM manual for this engine and that will help you alot.
 

dazk14

Ensign
Joined
Jul 22, 2008
Messages
966
Re: 72 50 hp Johnson wont turn over...

Do the choke update first...although rebuilding the carbs is a must do maintenance item and fairly simple.


(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.
 

Freddyb18

Cadet
Joined
Nov 2, 2011
Messages
14
Re: 72 50 hp Johnson wont turn over...

UPDATE***

Thank you all for your help on this!

I got an OEM carb rebuild kit from a local repair shop. The guy that ran the place was awesome. Very patient. He walked me through some easy to make mistakes and even drew me some horrible little pictures lol. I found that there was a lot of that little plastic piece, (I'm gonna call it a gasket) in the low speed jet. Rebuilt the bad boy and got her on the water. The batteries in my boat had gone under a lot of stress in the last couple of days, after a full charge it fired right up. I took it out this afternoon and it ran like a D-R-E-A-M. I need to fine tune the low end still, but I got it pretty close with the rebuild. It is an amazing feeling to get in the water, firing your engine right up, and flying to your fishing spot with full confidence in the engine. I have to admit, this little 50 hp Johnson certainly gets my 15' Terry Bass boat movin'. Ton of fun, plan to take it out for a little more fun in the morning.

THANK YOU TO EVERYONE!!!! I LOVE THIS FORUM, YOU GUYS ARE GREAT.

BTW, any other newbies checking out this thread, I found a lot of good info in the "top secret" file.

THANK YOU THANK YOU THANK YOU!!!!

Look out Mr. Whiskerfish, here I come.
 

1946Zephyr

Vice Admiral
Joined
Oct 21, 2008
Messages
5,556
Re: 72 50 hp Johnson wont turn over...

Coolness. Glad to hear it. Those old 50's are cool motors. I like the design.
 

dazk14

Ensign
Joined
Jul 22, 2008
Messages
966
Re: 72 50 hp Johnson wont turn over...

Here you go, $24.99 delivered...Put my shop out of business :facepalm:...

http://www.ebay.com/itm/1972-JOHNSO...anuals_Literature&vxp=mtr&hash=item25685eae14

Go get 'em! I'd suggest doing the choke mod, before final idle mixture adjustment, in case the auto portion of the choke is not allowing full and complete opening.

The idle mixture instructions are laid out straightforward in the manual. Do NOT use aftermarket manuals or you WILL be feeding my shop.
 
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