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View Poll Results: 1976 Johnson 70 hp
Carburetors 3 33.33%
Fuel tank 3 33.33%
Lower end problem 2 22.22%
Shift linkage problem 1 11.11%
Voters: 9. You may not vote on this poll

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Old 10-13-2014, 09:34 AM   #1
Johnmari
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Default 1976 Johnson 70 hp no power under a load

I have done the update on the carburetors, replaced strater, coil, plugs, fuel pump, primer bulb. The motor sounds and runs good on the muffs but as soon as I bring it and put it on the water and try to put it in gear it dies or will only idel at low speed for a short time and then die. If I try and idel it all the way up it just dies. I am at a loss and don't know what else it could be? PLEASE HELP ME I JUST WANT TO GO FISHING
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Old 10-13-2014, 10:47 AM   #2
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Default Fuel?

John is your fuel new and clear of ethanol separated water? Water separator clear?
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Old 10-13-2014, 11:12 AM   #3
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New fuel and yes water separator is clean
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Old 10-13-2014, 11:32 AM   #4
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Does it come to life when you hit the choke under load?
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Old 10-13-2014, 11:41 AM   #5
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No it just dies
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Old 10-13-2014, 02:26 PM   #6
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Have you done a compression check just to know?
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Old 10-13-2014, 03:10 PM   #7
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I would look at the simple things first....

You need air, spark & fuel to work.... sounds like its getting air & spark. I think its fuel issue. Old 2 strokes can be VERY fussy.

Do a compression test first... note the compression in each cylinder. it will tell you if the motor is good or not.

Who did the carb work? They could be out of whack and need adjustment or they might need to be synchronized. What do your spark plugs tell you?

Check your fuel lines from tank to motor to make sure there are no kinks in the line. Replace all of your old fuel lines as they can delaminate from the inside and cause a blockage.

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Old 10-13-2014, 03:44 PM   #8
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Sorry I meant to put the Compression is 120 psi on all cylinders. I have replaced all fuel lines and put the new style connector on the tank and eliminated the connector on the motor housing and went directly to the fuel pump. All of the carburetors open at the same time and all choke valves open and close at the same time I have also cleaned the tank. There are no kinks in fuel line it all runs smooth. It just will not run under a load on the water it is good and will idle all day on the hose muffs on the muffs I can put in gear and the prop turns like it wants to go.
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Old 10-13-2014, 06:41 PM   #9
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Well, it sounds like carbs or fuel pump....

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Old 10-13-2014, 07:01 PM   #10
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Default Ignition timing!

Something is wrong with the spark advance.

Opening the throttle should move a linkage with control over the ignition timing.

I speculate that this is not happening and while extra fuel air mix is being introduced, the timing is not right for it to run correctly.

Observe the frame that holds the ignition components under the flywheel.

There should be a linkage from the carbs up to it.

That linkage should rotate the frame as you advance the throttle.

Don't expect a linear relationship between the two.

It may start moving only a small amount, then a large amount and finally have no more movement with some increased throttle left to be had.

A link between the carbs and the ignition may be unclipped. Look closely!

P.S. no 6 pack needed, regular Oreo cookies will be just fine!
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Old 10-13-2014, 07:02 PM   #11
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Johnmari, I was just browsing through the forum and noticed that you are fairly new to posting on the forum and glad you have joined us. Have fun and enjoy the Winni Forum while making many new friends.

Sounds like the members are trying to help with some excellent suggestions. Best of luck.

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Old 10-14-2014, 07:33 AM   #12
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Thanks for all of the suggestions I am going to look for the linkage between the carbs and timing the only thing I seen that advances it is a roller arm on the carbs and I am going to pull the carbs off and go through them again and make sure there is no trash from the old fuel pump stuck anywhere.
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Old 10-14-2014, 09:38 AM   #13
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The pic you've posted shows the area of concern. I've recently set up my 2002 Mercury 50 after some major carb work. I have the manual which has pics with good labels. I realize it's a different brand and a newer motor but the concept should be the same.

The set up required aligning the various linkages in a certain order. I found mine to be significantly off. That was the set up from a FACTORY AUTHORIZED SERVICE CENTER after they replaced the power head years ago. The correct set up resulted in much better performance!

I suggest that you get a hold of a manual and follow the set up from scratch. Even if this isn't the big problem it's good to get this right.
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Old 10-15-2014, 07:35 AM   #14
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Spark plugs are as follows. Number one was coffee brown two and three still look new like no real change. I pulled and checked spark and it was good on all. Then I pulled plug wires while it was running the top one made it die the one in the middle made it run bad and the bottom one had no change. Is that because of a bad coil or a dead cylinder or bad power pack? It was sparking when I checked the spark on it. I have already replaced the top coil it is new and was told the other ones was good but now I am not so sure? Thanks for all the help.
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