1976 75HP Johnson Diaries - Bogging under load

[dkski]

Well, I bought this motor thinking it was an easy fix...what a dumb _ _ _! When I first bought it I checked compression 140 on all 3. Ran at an idle but as soon as you gave it throttle it bogged down and would stall. I thought it may need the carbs cleaned and or rebuilt so I took it to my local marina and got all three cleaned and re-built for $198.00 ( i now know i could've done it myself). After the cleaning, same problem...I was told it needed a power pack by the dealer. The dealer said I was wasting my money on an old motor...they think we should all own new motors worth more then the boats. I bought the power pack and did it myself. Now it seems to throttle up in neutral but bogs and stalls in gear when you throttle up. I cannot seem to figure out what to check next?

It has new plugs
new power pack
all new carbs (rebuilt)


Help please?

 

[Big Bubba]

Re: 1976 75HP Johnson Diaries - Bogging under load

You might have a bad coil or spark plug wire. You should prucahse an in-line spark checker and see if your getting spark on each of the 3 cylinders. How does your coils look? Are they cracked or very old looking? That waht I would do next and yeap, I have a 1983, 70 horsepower that is doing the same thing and I am trying to figure it out myself but I am deployed right now and can't troubleshoot until I get home next year. Also how old is your fuel and what about your fule bulb is it new or old. Let me know maybe we can help each other out and I can read what your fix action was and see if that is waht is happening with mine. Check the coils if there firing, check fuel primer bulb, make sure your fuel tank is clean inside and you have clean fresh fuel/oil mixture, 50-1 ratio, which I think is 16 onces to 6 gallons of gas but use a oil mixure that I bought in the baoting section of Wal-Mart which makes mixing the gas/oil mixture a breeze. Well let me know I am interested. One more thing you might need to check your linc and sync and see if it is right and please buy the OEM factory service manual specific to your motor. Go to kencookbooks.com or outboardbooks.com. Hope this helps you out? Take care, Bob

 

[steph13]

Re: 1976 75HP Johnson Diaries - Bogging under load

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[steph13]

Re: 1976 75HP Johnson Diaries - Bogging under load

Ineed help with my 1978 johnson 70hp

 

[dkski]

Re: 1976 75HP Johnson Diaries - Bogging under load

Thanks Bob...keep safe and I will keep you posted on my progress. I will check the spark. I haven't done that yet...

 

[Big Bubba]

Re: 1976 75HP Johnson Diaries - Bogging under load

DKSKI,
Yeah, get yourself a in-line spark tester and check the spark when the engine is at warm up temperature and when it starts to do this and see if your losing spark from either a bad spark plug, spark plug wire, coil breaking down under the heat, or your power pack going south. I would check the inside of the fule tank and check for contaminants like water/moisture or just dirt particles flaoting around inside the tank. Check the timing by doing a link andd sync. Yeah, P.M. me and let me know if you ever fix your outboard becuase mine is doing the same thing as yours is. I am very curious and will try or test this on my outboard when I get home next year. Thanks again, Bob

 

[tashasdaddy]

Re: 1976 75HP Johnson Diaries - Bogging under load

also check for ethanol poisioning. http://forums.iboats.com/showthread.php?t=299680