intermittent outboard issue

sly_karma

sly_karma

Crew Member
My old Johnson 140 cross flow ran strongly after its winter rest, then after 3-4 hours' use, it suddenly wouldn't rev out past 2500 rpm. Not missing, just WOT was only yielding half revs. I changed out the fuel filter cartridge, no change. After a few minutes of this, it suddenly surged back to full rpm without warning. Has happened several times since with no reason I can think of. If it were coil or CDI problem it would either miss on one cylinder or one bank respectively. Took it out today wanting to tinker and of course the problem didn't appear.

Anyone? Engine is a J140 from 1980, pre-VRO system.
 
collapsing fuel line? try running a different fuel supply direct to your fuel intake, my honda did this, was super pain in the arse to figure out.
 
I own a 115 Johnson cross flow pre VRO as well and had a similar problem to yours.After a new fuel pump and replacing
fuel lines with no results,I rebuilt the carbs and fixed the problem.I think the carb kits were $18.00 each and easy to do.
If your at all mechanically inclined,I'd give this a try first.
 
Thanks for the responses. More detail: the problem cuts in and out as suddenly as a switch, but from several minutes up to an hour apart. Doesn't seem like fuel starvation from fuel line issues, that would be present more or less all the time at WOT. There are two tanks with separate primer bulb for each, then into common filter. Problem is present on either tank. Both primer bulbs firm up without problem. Carbs were overhauled summer of 2012, ran all last season without issue. The only fuel issue I can think of that fits the circumstances is some crud blocking a high speed jet, then being dislodged, then more crud causing the problem to repeat. But I have that big cartridge filter, it's changed yearly and of course I changed it right away when the problem began. There is a filter screen in the fuel pump but that was perfectly clean both times I looked at it. Bow tank was run down to about 20% level for winter and stabilised with Sea Foam. Stern tank was emptied completely. Fuel lines in hull were removed and drained whilst some hull fibreglass work was doen over winter. I did the spring runup with more Sea Foam added to bow tank and ran it for 20+ minutes while it coughed up all that gunk that two strokes seem to produce. Then filled the tank with regular 50:1 and all ran well for two tanks' worth before this issue arose.

I'll run through the shop manual carb diagnostics more carefully, see if I can discern some problem there. One thing that does make me wonder is whenever the engine is tilted forward into trailer mode, some fuel dumps into the splash well. That doesn't seem like correct function. If anyone sees something in the additional details I've provided, please let me know.
 
Carefully check the o-ring on the fuel line connection. It can act this way. It does sound like you might have an air leak. The other possibility is the cdi as it can work intermittently. One thing that went wrong on my '87 225 that had the same symptoms as yours was the shift interrupt switch system. It corroded and then would not work properly. Good times.
 
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Could be an intermittent power pack issue, I dont believe this engine has a shift interrupt switch.
Check all electrical connections and grounds for corrosion/clean them up to start. Does this engine have one or two powerpacks? One may be dropping out causing only half the engine to fire. It will probably still run but not well. If you have an inductive timing light you can see if that cylinder is firing when the problem comes up. CDI has a good troubleshooting guide http://issuu.com/cdielectronics/docs/cdi_troubleshooting_guide_-_2012_1?e=2044661/2001100
 
I agree with the last post. I don't know about the 140 but the 1987 225 had two completely separate ignition systems and the way the shift interrupt system worked was to momentarily ground out the port side bank ignition. Problem was that if it stuck grounded out you might be able to start it but it would only get about 2500 rpm because only three of the six plugs were firing.
Whatever you do be methodical and don't overlook anything but try not to replace things because of what some guys on the internet say it might be. These engines are not real hard to diagnose if you go slow. Timing light is a good tool. An inductive tach is also a good tool to use with these. I would look at ignition first because that is what seems to go bad with corrosion while not being used. Clean all the terminals on the coils with emery cloth and grease them before you do anything if they are corroded. Bad plugs, coils, connections and bad grounds can cause the power pack to be ruined but may work at times. Have fun.
 
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Thanks for the replies. Yes this engine has two CDI packs. I will get out there this weekend and see if I can make the problem recur. Timing light is ready to go.

Sent from my SGH-I747M using Tapatalk
 
with the detail you added, i would def look at the shift interupt swt. Its a spring loaded swt that is actuated by the shift cable motion.. it loads up as you change from neut to fwd or neut to rev.
As noted above post, the swt briefly ciuts the ign to allow a gentler engagement of the shift dog int the gearcase. If the swt is faulty or cable is mis adjusted you get your symptom
 
Try running with the cap [motor cover off] .I had the same motor and problem it was a plug wire arcing on the hold down lever. May the force be with you :)
 
For all its worth take it took a good mechanic. These motors need a little nursing...I know did it for years.... I fixed what I could. It could be the power pack or many other things... Sure you save a little but it sounds like you still can't find problem. Its probably better to get it all looked at anyways...

I doubt you will spend much anyway. There easy to work on.
 
If your in south island area around Duncan area Jamie's outboards is awesome he does it in your driveway. Totally mobile.

Tipton's Lake Cowichan but Rod isn't there anymore.

Or Chris at Forsche marine out in Sidney...

Mainland or up island I don't know... With my old two stroke those are the guys I used.
 
79 Jimmy said:
He can look all day, that switch doesn't exist on his engine....
Click to expand...

Yes and no... the circuit is there but it uses the neutral switch in the helm controls. On my list for testing, the shop manual gives a procedure. Trouble is all of this has to happen on the water. And the problem is intermittent.

Spring, thanks for the mechanic tips, but I live in the Okanagan.
 
sly_karma said:
One thing that does make me wonder is whenever the engine is tilted forward into trailer mode, some fuel dumps into the splash well. That doesn't seem like correct function. If anyone sees something in the additional details I've provided, please let me know.
Click to expand...

It should not be leaking fuel when tilted up. Something isn't sealed on the fuel intake side; could be a gasket on one carb, could be a fuel line etc. If this is the case you're probably running lean on two cylinders intermittently. I'd definitely have a close look at the fuel intake. Lean on a two stroke = bad news for those cylinders. Should be two dual-throat carbs on that crossflow so if one is lean then two cylinders will be affected.
 
79 Jimmy said:
Start with the basics, often the simple stuff is overlooked. Good luck and let us know how it turns out.
Click to expand...
truant said:
. Bad plugs, coils, connections and bad grounds can cause the power pack to be ruined but may work at times. Have fun.
Click to expand...

I had a very similar intermitten problem with rpm suddenly dropping and then goosing back up again ...with a 2 stroke - was solved easily by replacing all the plugs. Also when checking the old plugs I took out, one of them the gap was out a fair bit.
 
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