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Author Topic:   Running rough
Ben posted 06-05-2002 08:39 AM ET (US)   Profile for Ben   Send Email to Ben  
I was out last night and for the 3rd time this year and the boat continues to run rough - 1977 200 HP Johnson. I added a bottle of carb cleaner prior to the first launch - I put it in 40 gallons of gas (it stated it treats 25 gallons but the auto mechanic said 1 can was enough). I had 28 gallons of gas left from last season (with stable in it) as well as 12 fresh gallons of premium. The boat looses power, gains it back, and looses it again at high speeds. It also idles rough. Is this a symptom of the carb treatment? Once I go through the first tank do you think a fresh 40 gallon will cure the problem? Would you add additional gas treatment like the OMC product or a water remover? Suggentions?


OutrageMan posted 06-05-2002 09:05 AM ET (US)     Profile for OutrageMan  Send Email to OutrageMan     
I saw this same problem when I used a shock treatment of Ring Free. You basically have 2 different additives running through there.

I wouldn't sweat it until you have run about half a tank of additive free fresh gas through it. If it continues, then have the mechanic look at it.


sklein posted 06-06-2002 12:09 PM ET (US)     Profile for sklein  Send Email to sklein     
I had what seems like a similar problem with my 1977 115 Johnson. Turned out to be an intermittent transistor in the ignition power pack. Mine was difficult to diagnose in that it had good spark at idle, but engine wouldn't run well at higher rpm. It made driveway diagnostics impossible.

The only way I could prove ignition was to go out and run above planing speed, shutdown quickly and check plugs. The plugs from the running cylinders were clean and white, the non-running cylinder was wet.

I did all the wire checks and coil swaps and proved it was in the power pack. Being an electrical engineer and a DIY'er to a fault, I un-potted the power pack, found the bad transistor, and repaired it.

Don't rule out an ignition problem, and start with the simple and cheap parts before buying a power pack.


grandmufti posted 06-07-2002 12:04 AM ET (US)     Profile for grandmufti  Send Email to grandmufti     
How did you remove the epoxy from the powerpack?I had the identical problem as you on my 9.9 Evinrude and would like to repair my powerpack for a spare.The dealer bit me for 101 bucks tax included for a new one.
sklein posted 06-09-2002 08:40 AM ET (US)     Profile for sklein  Send Email to sklein     

The potting material isn't a hard epoxy, it is somewhat elastic. I found that it breaks down quickly with a little heat. Push a hot soldering iron into it and the potting crumbles away a little at a time.

I've actually repaired two of them now, each slightly different. One had a plastic housing which I had to cut away the bottom to get the circuit board. The other was in an aluminum housing. That one I put on a hot plate for a while and got it good and hot. I was then able to pry the whole thing out and then chisel away at the potting with the soldering iron.

The transistors I found to be bad were actually SCR's. One of the power packs had SCR's which could not be cross-referenced by anything I could find. The other had part numbers which could be cross-referenced to NTE5429.

I might be able to help with some more info if you decide to try this and have questions.

Disclaimer: My knowledge is limited to a 1977 Johnson V4. It may not be applicable to anything else.


jimh posted 06-09-2002 08:53 AM ET (US)     Profile for jimh  Send Email to jimh     

Hats off to you for the story of the best electrical repair on an outboard motor I've heard.

It has been my experience that often mechanics are great mechanically but awful electrically. It's good to hear of someone who didn't have to spend $300 to fix a bad $0.25 transistor.

grandmufti posted 06-09-2002 11:21 PM ET (US)     Profile for grandmufti  Send Email to grandmufti     
Thanks for the reply.The next rainy spell we get I will go at it,
Ben posted 06-10-2002 09:16 AM ET (US)     Profile for Ben  Send Email to Ben     
Thanks for all the good information. I pulled the plugs and they were very oily. I changed them and added 6 gallons of new fuel - with less oil then recommended to try and balance the existing fuel mixture. The boat is running much better. I remember the original owner telling me he always went 13 gallons of gas to 1 quart of oil - this always made me nervous. Maybe it caught up and I had tool much gas/oil mixture. Do motors vary that much? Is mixing gas and oil a trial and error or a science?


sklein posted 06-10-2002 12:24 PM ET (US)     Profile for sklein  Send Email to sklein     
I also run 1 quart to 12-13 gallons. Typical OMC recommended mixture is 50:1. 1 quart oil to 13 gallons gas = 52:1. I wouldn't run much lighter on oil than that.

Mixture isn't trial and error based on plugs. It's an issue of proper lubrication of the engine. Too light on oil and pistons stop sliding and bearings stop spinning. Stick with the OEM recommendations.


Bigshot posted 06-10-2002 01:15 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Intermittent running is not from oil or carb cleanermore like an electrical issue or something as simple as a fouled plug. What "I" would do is this. Get 6 new plugs(L77JC4 champions). Do a compression test while plugs are out and write it down to compare next year etc. Install new plugs and also drop some gasline antifreeze aka water absorber) in the tank. To me it sounds like you have some water in the tank and it is picking it up at high speeds. If this is a Revenge, I will almost put money on it. Mine did this constantly. If no dice in next 40 gallons, have carbs cleaned.
Ben posted 06-10-2002 10:12 PM ET (US)     Profile for Ben  Send Email to Ben     
Thanks again to all - it is a 77 Outrage (bigshot). How often do you add the water absorber - every fillup??


Bigshot posted 06-11-2002 10:51 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
No! just when it starts acting up and definately in the beginning of the season. The crap is cheap, like $.79, just throw like 3 in there and let her rip, throw in a techron too to clean those carbs and decarbonize it.
bsmotril posted 06-12-2002 02:45 PM ET (US)     Profile for bsmotril  Send Email to bsmotril     
You may have water in the bottom of your tank getting sucked into the carb causing rough running. Did you leave your tank full over the winter, if not, you may have gotten condensation inside. I am assuming here that you do not have a water separating fuel filter. If you do have a separator, you can eliminate this potential source of the problem by replacing the cannister, or emptying the sump of the filter. I think the water removers do more harm than good as they are alcohol based which is bad for the rubber pieces in the fuel system. A separator is a preferred solution IMHO.
Bigshot posted 06-17-2002 11:07 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Seperator is the preferred solution but you have to get the water out and using the alcohol won't do doodoo unless used constantly.

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