1975 johnson stinger 75hp, No power, please help.

snowflake1

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Jan 14, 2007
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31
Guys i'm pretty stumped on this one.
Recently bought a 16 foot peterbourough boat with a 75hp johnson stinger for a little fun with intentions of doing a little watersking.

I'm really disapointed in the performance of the motor. It can barely get the boat out of the water.

Went home pulled the carbs off cleaned them + 3 little jets at top also used compressed air to clean off.
Also was told the a planer(spoiler) on the rear of engine would help the boat plane better.

Back to the lake(7pm). Much better, boat was able to pull itself out of water,(don't know about a water skier though) ran it for about an hour, i'd say test run was positive. Called it a day.

Today i went out on the lake with boat ran decent for about 15 minutes. Then it lost all power and just doesn't seem to be all there. It ides fine, starts fine, when i take off, powers not there, it takes forever for the motors rev's to pick up, Hobbled back to the marina.


1. Compression is 140 #1 cylinder
130 #2 cylinder
140#3 cylinder
2. Carbs where cleaned, twice
3. throttle linkages are operating like they should, choke as well
4. spark is strong on all 3 plugs
5. water pump is good(i pulled the lower unite apart)

Could anyone please help me out with this problem, it seems so weird.

Could a reed valve/fuel pump be playing tricks on me, i don't see much more that can be replaced?

Thanks for looking.
 

snowflake1

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Messages
31
Re: 1975 johnson stinger 75hp, No power, please help.

Should have mentioned model:

1975 johnson
75ESLR75B
 

tashasdaddy

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snowflake1

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Re: 1975 johnson stinger 75hp, No power, please help.

Thanks tashasdaddy.

I never checked for spark at the moment it wasn't running good, only later once home, by then motor had a chance to cool off. If it's heat/spark related, i don't have a clue what it is.

This is the second time it does this. First time it ran awesome for like 15/20 minutes made a couple hard turns with boat(maybe to much load on motor)and then all of a sudden power slowly died, lost speed and was unable to get out of water, limped back to marina

I did get the little jet in the lower bowl behind the drain screw.
I also did most of the instructions for carb cleaning and installing.

-Soaked overnight
-compressed air
-Blew threw gas line upside down and upside right for proper seating.
-proper float position
-All jets are visually clean, however the 3 mini little passages in the ceiling of the carb, i can't get wire in the center one, only the two outer passages.


Any help would be great,
Thanks
 

tashasdaddy

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51,019
Re: 1975 johnson stinger 75hp, No power, please help.

it sounds like may be you drop a cylinder, a coil heated up, and failed. run it again and check the spark, i think you will find one not firing. then you can come to shore, and completely swap the suspect coil, with one that was working. if the problem follow the suspect coil, you found the culprit. if the problem stays possible power pack problem.

you may have to go back a pull the core plug on top of the carb, to get to the 3 orifices, you will need new plugs for there. the reason, if it is not getting enough gas when idling, it is not getting enough oil, to lubricate. i use a paper clip to go thru the throat, to clean them.
 

snowflake1

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Re: 1975 johnson stinger 75hp, No power, please help.

Ok, so it might be a coil pack heating up and simply not working, good i'll give it a shot.
I'll clean the 3 orifices to.

I'll do a little running around today, and keep posted on how this works out.

Thanks
 

snowflake1

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Messages
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Re: 1975 johnson stinger 75hp, No power, please help.

Update:

-redid the carbs
-Pulled the reed valves to have a look(reinstalled with new intake gaskets)
-2 new coils
-new fuel pump

Engine ran for a half an hour but never really seemed to be willing to rev up easily.
Started to experience some knocking and some weird clunking sound. Then power seemed to go out the window.
Pulled the lower unite allen key out, and the worst smell came out as well as a bunch of hot pressurized black oil. Propeller doesn't rotate as easily as it use to. There seems to be a dent on the port side of the lower unite coming from the inside.
And to top it off, the motor refuses to fire.
I think i just blew my motor and lower unite in one shot?
Wow, this really sucks!
 

snowflake1

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Re: 1975 johnson stinger 75hp, No power, please help.

i guess there's really no hope for this thing
 

snowflake1

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Re: 1975 johnson stinger 75hp, No power, please help.

Checked for spark today and there's spark.
Turned it over to see if it would fire, fired right away, shut it off just as quick.

Rechecked compression on cold motor
#1cyl=150psi
#2cyl=130psi
#3cyl=150psi

It never ran right, never pulled strong, leaked gas when motor was raised(still a mistery where it was leaking from)

So i started taking it apart, and found #2cyl really beat up.
Edge was broken off and broken pieces where jamed into piston and cylinder head. Amazing was still working.

Take a look at picture!

http://s314.photobucket.com/albums/ll440/snowflake2002/?action=view&current=IMG_2558.jpg


Cylinder is scored so i assume it's going to need a piston 1 size larger. The thing is, I don't want to put in the same OEM piston's. I read somewhere that on this model(johnson stinger 75hp-75eslr75b) doesn't seem to last as long as other models. Piston rings are to close to surface of piston which creates a weak point. If this is true, i don't like the idea of using the same design pistons.
What options do i have?
Thanks
 

snowflake1

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Re: 1975 johnson stinger 75hp, What pistons choice for rebuild?.

Re: 1975 johnson stinger 75hp, What pistons choice for rebuild?.

Any advice on the Piston selection or should i just stick with new .020/.030 OEM oversize?

Should i do all three since i'm there or can i get away with only doing one?

Any advice would be great.
thanks again
 

CharlieB

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Joined
Apr 10, 2007
Messages
5,617
Re: 1975 johnson stinger 75hp, No power, please help.

What is that old adage?

If it ain't broke.............

Many will tell you that you should do all cyl the same, but then again just as many will tell you that you can get by just doing the one.

Factory warranty work would only pay for the one.

Either way the engine will run within accepted standards, so it is really up to the owners personal preference.

Finding the CAUSE of the problem is of most importance. Was that carb a bit lean causing some heating, damaging that cyl and continued running with a compression lose/misfiring carboning it to mask the leanness?

Carefulyl and throughly clean the piston dome and skirts with solvent, look for any differences in the surface finish that could indicate the cause of the failure. Post more pictures so that we may be able to help you determine the initial problem.

Factoy pistons work, many aftermarket pistons work. There again, personal preferences rule.
 

Stinger75

Cadet
Joined
Feb 15, 2009
Messages
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Re: 1975 johnson stinger 75hp, No power, please help.

putting in just one oversize piston is going to cause a serious imbalance.
 
Joined
Jul 30, 2008
Messages
172
Re: 1975 johnson stinger 75hp, No power, please help.

A 16' boat is big for that motor if it's a shortshaft. How heavy is the boat, and what pitch prop are you trying to use? Short or longshaft?


Guys i'm pretty stumped on this one.
Recently bought a 16 foot peterbourough boat with a 75hp johnson stinger for a little fun with intentions of doing a little watersking.

I'm really disapointed in the performance of the motor. It can barely get the boat out of the water.

Went home pulled the carbs off cleaned them + 3 little jets at top also used compressed air to clean off.
Also was told the a planer(spoiler) on the rear of engine would help the boat plane better.

Back to the lake(7pm). Much better, boat was able to pull itself out of water,(don't know about a water skier though) ran it for about an hour, i'd say test run was positive. Called it a day.

Today i went out on the lake with boat ran decent for about 15 minutes. Then it lost all power and just doesn't seem to be all there. It ides fine, starts fine, when i take off, powers not there, it takes forever for the motors rev's to pick up, Hobbled back to the marina.


1. Compression is 140 #1 cylinder
130 #2 cylinder
140#3 cylinder
2. Carbs where cleaned, twice
3. throttle linkages are operating like they should, choke as well
4. spark is strong on all 3 plugs
5. water pump is good(i pulled the lower unite apart)

Could anyone please help me out with this problem, it seems so weird.

Could a reed valve/fuel pump be playing tricks on me, i don't see much more that can be replaced?

Thanks for looking.
 
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