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No power in the lake

R

radioman69

New member
I have an Model70EL760...serial j4532209. 70 hp 1976 Johnson outboard.
Rebuilt carbs, compression checked and good, new hoses, clamps,
Fuel pump, tank, new coils all with correct ohms. Starts and idles great with muffs and in tank. Put it in the lake and can't get acceleration. Bogs down and sputters. Can anybody help???
 
Right. Marginal spark will give these symptoms. Should jump a good 7/16 inch with a nice white/blue snap. If you get that then you have proper spark. No good to simply check spark using the spark plugs. Did you also try......when symptoms begin.....to pump the primer bulb? Could there be contaminated fuel?
 
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timguy said:
Right. Marginal spark will give these symptoms. Should jump a good 7/16 inch with a nice white/blue snap. If you get that then you have proper spark. No good to simply check spark using the spark plugs. Did you also try......when symptoms begin.....to pump the primer bulb? Could there be contaminated fuel?
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I have tried pumping the primer bulb but did not check the spark in the manner you suggested. I will try that. Fuel is good.

In he tank and with muffs. I can get 5300 rpm. Put it in the lake with back pressure and it sputters and has no power.
 
have tried pumping the primer bulb but did not check the spark in the manner you suggested. I will try that. Fuel is good.*

In he tank and with muffs. I can get 5300 rpm. Put it in the lake with back pressure and it sputters and has no power.
 
Running at 5300 RPM with no load is not a good idea.-----You might need a bushel basket to gather all the parts.----Are the high speed jets, the ones found screwed into the carburetor bowl confirmed to be clean, yes or no ?----These jets are about 5/8" long with a 1/4-20 thread.
 
racerone said:
Running at 5300 RPM with no load is not a good idea.-----You might need a bushel basket to gather all the parts.----Are the high speed jets, the ones found screwed into the carburetor bowl confirmed to be clean, yes or no ?----These jets are about 5/8" long with a 1/4-20 thread.
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Ok...won't do that again. Did not take these out when rebuilding carbs. Found a small bit the size of the hole in the jet and pushed through the holes. The manual I have said this was ok. If not, please let me know.
 
The bit may be too small and might not clean out the thin crust at the outside wall of the bore. My guess is that your still not opening the orifices to specs. I "ALWAYS" remove the jets and clean them in my hands using a welding tip cleaner and throttle body cleaning spray. this is a VERY strong solvent and can help dissolve deposits. I also have a set of machinist bits that also help with sizing. A 0-1" micrometer will then be used to double check size on a slightly tapered brass probe that I insert into the jet. In all my years, I could tell you truths of what I have found...........you would not begin to believe what people do to metering jets.
 
timguy said:
The bit may be too small and might not clean out the thin crust at the outside wall of the bore. My guess is that your still not opening the orifices to specs. I "ALWAYS" remove the jets and clean them in my hands using a welding tip cleaner and throttle body cleaning spray. this is a VERY strong solvent and can help dissolve deposits. I also have a set of machinist bits that also help with sizing. A 0-1" micrometer will then be used to double check size on a slightly tapered brass probe that I insert into the jet. In all my years, I could tell you truths of what I have found...........you would not begin to believe what people do to metering jets.
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Ok....I'll remove them and clean.

I'll try anything....desperate to get this thing going. Like to night fish in the summer.
 
The term " good compression " is used a lot.-----Means nothing to me.----On my tester your motor would show about 140 PSI.----What are your numbers ?----Could be running on 2 cylinders.---Checked reed valves ?------Did this problem show up suddenly ?----When did it last run well for you ?----Just bought it ?-----
 
Please answer more of the questions directed by Racer, like "when did the problem start"? Compression is nothing to write home about either.
 
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