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Motor bogs without muffs & wont gain speed

J

JedPHannigan

New member
Ok so I have an 82' Johnson 70 hp. It had been parked for about 6 years covered. It ran fine before I parked it only lower unit problems. So I have pulled it out of storage and replaced the lower unit, new batteries, and rewired most of the boat.

After this I tried to crank it with surprisingly not much problem. To me it sounded fairly good "I tought" with the muffs. It tached up but sounded like a little sputter at mid to higher rpms. I took it to the lake to test it out but it wouldn't gain speed or tach up in the water.

After research I figured it was gummed up carbs. I rebuilt the carbs, replaced the fuel lines, and filter. Still same problems. I then pulled off the carbs three separate times letting them soak then cleaning again. Still the same problems.

I then began to feel it was a firing problem. I pulled the plugs and checked for spark each appeared to be fine. So I replaced the plugs. I took it out again same result "to start with" this time it ran the same then I wasn't expecting it but suddenly it ran awesome. Then suddenly it went back to the same thing.

I then replaced the coil packs, wires, and plugs. After everything I am still in the same situation and scratching my head. I have done lots of research to get this far with it because I am VERY far from a mechanic. I am still researching and am possibly leaning towards the rectifier or possibly gummed carbs I missed but I doubt it's the carbs and long and as many times I've cleaned them. Btw when I pulled the plugs even the new ones at least one or two were darker. I have found just buying parts can get to be expensive so if anyone has any ideas I would appreciate any help.

thanks
 
do you have a fuel water separator? Old gas dries out into varnish, putting new gas into old tank dissolves it, which can create a nice jelly that can clog things. Try running off separate 6 gallon portable tank. Its a guess, but you've gone through a lot of what I would have tried.
Also, when you clean the carbs, there are tiny little holes that need to be poked through with a thin wire, or blasted with air from compressor.
 
emac said:
do you have a fuel water separator? Old gas dries out into varnish, putting new gas into old tank dissolves it, which can create a nice jelly that can clog things. Try running off separate 6 gallon portable tank. Its a guess, but you've gone through a lot of what I would have tried.
Also, when you clean the carbs, there are tiny little holes that need to be poked through with a thin wire, or blasted with air from compressor.
Click to expand...

Thanks i didn't think of the old gas in that aspect. I poured a little in the tank & swished it but that was the extent of my tank cleaning. I will try a separate tank and see. I will also look into the fuel water separator because I don't have one. I soaked the carbs in Berryman's Chem Dip then cleaned with Carb cleaner then sprayed compressed air through all of the jets I could find several times. I didn't try the wire though. I didn't take into account it may have picked up more gunk from the old tank. It just blew my mind when it started running great then quit again that's what stumped me. I will pull the carbs one more time just to feel safe also

Thanks
 
Did you remove the high speed jets to verify they were clean ?-------These jets are screwed into the very bottom of the carburetor bowls ?
 
emac said:
do you have a fuel water separator? Old gas dries out into varnish, putting new gas into old tank dissolves it, which can create a nice jelly that can clog things. Try running off separate 6 gallon portable tank. Its a guess, but you've gone through a lot of what I would have tried.
Also, when you clean the carbs, there are tiny little holes that need to be poked through with a thin wire, or blasted with air from compressor.
Click to expand...

I didn't try to remove the high speed jets. This was my first time attempting any kind of carb repair but I will definitely do this while I have them off. I was a little intimidated initially but after three or four times of having them apart already the fear is gone. I did also forget to mention the one time it did run good after revving it for a while in the water the only repair I did before hand was replace the filters around the air box. I will check the jets more thoroughly and check for more air leaks while I have it apart

thanks
 
I also appreciate the help on this problem in advance to everyone and appreciate the patience. If it wasn't for YouTube and the internet I would be completely lost because I am definitely and outboard repair novice. I am in the process of cleaning the carbs again at the moment and will update as soon as I'm finished.

thanks
 
Latest update...I pulled the carbs back off and cleaned them again. I let them soak for an additional 40 minutes in Chem dip ran a wire in the Jets blew through with gum out and compressed air again. After putting everything back together I am still having the same result. At this point I am pretty sure it isn't the carbs although after research a carb rebuild was necessary due to the sit up time. If anyone has any other ideas please let me know

thanks
 
I saw no mention of a compression test, spark test,big blue snap,Also JED not good to rev high rpms in neutral with no load on engine,prop pushing boat,damage to engine could result..
 
I haven't made it as far as a compression test. I did pull the plugs while running to make sure each have spark & it appeared if even before replacing the coil assy. I will have to research more to know more of what I am looking for as far as spark. I have already researched compression test & that will easy enough. That was my next move on this project I have just been taking baby steps. I do appreciate the input of running higher rpms with muffs on that was the first anyone had mentioned that this could be bad on the engine. I will keep that in mind like I said I am a novice to mechanic work and I am feeling my way through educating myself as I go. I appreciate the knowledge

thanks
 
Ok so I purchased the equipment for the compression test and spark test and they are as follows. Compression is about 122 on all three cylinders. Spark at a 1/4" looked blue and about the same on all three wires. What else should I try
 
Run with a timing light and see if there are spark problems.---------------The real test for spark on these is a gap of 7/16" or more , does it jump that gap , yes or no ?
 
I don't have a timing light at this point to check I will check with a friend to see if I can borrow one. I did set the gap to 5/8" just to see and it appears to jump the gap fine on all three
 
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