problems with engine

chris812

Cadet
Joined
Feb 5, 2011
Messages
24
Hi all, I have been in the process of repairing a 1964 johnson 28hp engine. I Replaced the head and put in new spark plugs and wires as well as points. I started it up and it ran fine. when I got it in the water though it started fine then after throttling up it was cutting out or acting like it was not getting any fuel or fooding. it did smoke white smoke and smelt rich I adjusted the low speed and high speed but it was still doing it. I checked for spark and seemed to have good spark on both. it would rev up fine at first and would stay that way till you let off to idle then when you tried to throttle up it would not throttle up just no power. took the spark plugs out and checked them. top was black on bottom was wet and clean like it was not firing. so like i said it starts fine after letting it sit a min, rev it up, let off the throttle then try to rev again then won't throttle up. just smokes. I even turned the slow speed mix all the way in and it took awhile to cut out turned it back out slowly 1 full turn did the same with the high speed. did notice some differences but not much though.
any ideas? I am really getting frustrated here. if you need more info please let me know thanks.
 

Bosunsmate

Admiral
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Apr 7, 2012
Messages
6,129
Re: problems with engine

why did you replace the head?
do you think the bottom plug was wet with fuel or water?
 

chris812

Cadet
Joined
Feb 5, 2011
Messages
24
Re: problems with engine

the head was replaced because the old one had a striped spark plug and i could not use heli coil compression is good too tested at around 100 psi for both. And wet with fuel no water in it at all.
 

Bosunsmate

Admiral
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Apr 7, 2012
Messages
6,129
Re: problems with engine

Have you grounded bottom plug to engine and seen if it sparks?
 

chris812

Cadet
Joined
Feb 5, 2011
Messages
24
Re: problems with engine

yes i did. i plan to use a spark plug tester with the light and see what happens when its running.
 

82rude

Rear Admiral
Joined
May 8, 2012
Messages
4,082
Re: problems with engine

is this motors cooling system working.make sure shes spitting out water from the exhaust just below the cowling.
 

chris812

Cadet
Joined
Feb 5, 2011
Messages
24
Re: problems with engine

yes it is peeing good. it has new pump and the engine is staying cool even running for 3 min or so.
 

lindy46

Captain
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Nov 27, 2008
Messages
3,886
Re: problems with engine

You don't say if you replaced the coils. Could be a coil cutting out when it gets warm.
 

chris812

Cadet
Joined
Feb 5, 2011
Messages
24
Re: problems with engine

no I did not replace coils. will replace them (reluctantly) but if it continues do you have any other ideas?
 

lindy46

Captain
Joined
Nov 27, 2008
Messages
3,886
Re: problems with engine

Fuel pump? Before you replace the coils, try duplicating the problem. Then pump the bulb in the fuel line and see if she picks up and runs normally. Since one plug is wet like it's not firing, I'd still bet on a bad coil.
 

chris812

Cadet
Joined
Feb 5, 2011
Messages
24
Re: problems with engine

thanks, I tried that when I had it in the water pumped the bulb and it quit. flooded more than likely. I am changing coil today.
 
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