120 Johnson smoky startup; no start

jayjensen

Cadet
Joined
May 1, 2007
Messages
14
My 1988 Johnson puffs out the grey smoke on startup - hot or cold. I disconnected and plugged the VRO line and now mix at 50:1 and it still does it. I inserted some clear fuel line and I can see some bubbles but only downstream of the OMC spin on fuel filter-must be a small leak in it somewhere. What could cause that smoking?..it does clear the mosquitos away! (and the neighbors).

I dont think it is carb float needles/seats. The motor runs great....EXCEPT...

When I shut her down and she sits for say fifteen minutes, sometimes she will refuse to fire. There is no spark going to any cylinder. Let her sit for an hour or two and she fires right up....me not having touched anything. It almost has to be a heat related thing-cool enough while running but heating when stopped? I swapped the power pack with a spare I have but it does the same thing. I guess I could have two bad power packs but not likely. What other heat related gizmo could shut down the ignition temporarily? The engine does not appear to be overheating and I even disconnected the temps sensors.

The only other theory I have is that my Optima AGM battery is getting old (5 years). It has plenty of juice to spin the starter. It does, however, lose reserve voltage quickly when I shut her down and the fishfinder draws battery power down. Could I have plenty of juice to crank the starter, but not enough voltage to fire up the ignition?...Then after time the battery builds back up enough voltage to fire up?

Anyone know what amperage 120 alternator puts out? Thanks.
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: 120 Johnson smoky startup; no start

6 pages here of electrical test for J/E outboards, find yours. also they have to spin +- 300 rpms.

"http://www.boatpartstore.com/page28.asp"
 

Gary H NC

Fleet Admiral
Joined
Dec 1, 2005
Messages
8,972
Re: 120 Johnson smoky startup; no start

My 175 smokes like crazy when cold or on the muffs.Nature of the beast.
Also weak spark on any cylinders will increase the smoke due to unburnt fuel oil mix.
Follow TD's link and do some electrical testing.;)
 

HighTrim

Supreme Mariner
Joined
Jun 21, 2007
Messages
10,486
Re: 120 Johnson smoky startup; no start

You can also have that battery load tested for free, most battery shops will be glad to do it for you :)
 
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