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Problem w/ 1988 Johnson120
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| tedious |
Posted on 05/26/12 - 5:20 PM
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John, you're likely looking at dirty jets - leaking or stuck floats would behave differently. But if you understand carbs, just do a full rebuild - not worth fooling with any half measures.
Link and sync is the process of adjusting the linkages to synchronize the carbs and the spark advance. It's not hard with the factory manual. I got my carb kits and factory service manual from marine engine.com and I would recommend them.
Tim
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| Mr T |
Posted on 05/27/12 - 5:57 AM
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I agree the issue sounds very much carb related. I am going through the same type of issue with my 1990 Evinrude 88, (essentially the same motor in many ways.)
First thing I did was get the rebuild kit part number off the BRP website.
I went to the auction site ( sounds like tree day) and found a seller who caried the Sierra carb rebuild kit for under 19.00, with free shipping. That my project for next week.
If it's worth anything, the motor I have does not have the VRO, but very similar issues. I'm pretty sure it's gunked up jets.
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| contender250 |
Posted on 05/27/12 - 8:03 AM
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Tom Clark: something is not right with your friends 140, my engine runs just fine at any speed/rpm's . Also do you really think that OMC would release an engine that did not operate correctly at a mid range RPM?
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| thegage |
Posted on 05/27/12 - 8:27 AM
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If you do have plastic carb bowls, make sure they aren't warped. I had to do it over once I found the old bowls didn't seal fully.
John K.
John Kittredge
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| John Coryea |
Posted on 05/28/12 - 4:22 PM
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Tom,Kamie and all-
Thanks for all the additional info..The Outrage sat at the dock all weekend,finished the Dridek.I dared not run it for fear of burning something up .if I indeed do have a lean problem..SO, if I run a fresh mix of gas/oil, am I in danger of damaging the engine? So add triple dose of seafoam? I'm thinking carb rebuilds in any event. The concensus is not a vro problem at this point.
Thanks,
John
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| tedious |
Posted on 05/28/12 - 7:09 PM
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John, from your description, I would say there is some risk of damaging the motor if you run it at speed.
Tim
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| John Coryea |
Posted on 05/29/12 - 5:02 AM
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Hello all-
I left out an important thought in my last post.
I only need to run the engine/boat around one mile to the boat launch..If I run at low speed, would that be ok? Need to get to another mechanic. Thanks.
John(crow)
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| tedious |
Posted on 05/29/12 - 5:54 AM
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John, you said it ran fine at low speeds, so I think you'll be fine. Good luck!
Tim
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| John Coryea |
Posted on 07/17/12 - 4:58 PM
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Hello all-
Sorry about the duplicate post..computers aren't my thing. Anyway,an update on the mid range running problem on my 120 Johnson VRO
Carbs have been cleaned and new kits installed
One coil replaced as it showed high reading.
Runs great from idle to @2K or 3k to wide open..in those ranges ,it runs strong and well. Dies between 2-3K. Am I missing something? It always starts right up,use non ethanol fuel
and have a fuel/water separator installed. System was pressurized for air leaks.
Thanks in advance,
John (crow)
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| Joe Kriz |
Posted on 07/17/12 - 5:00 PM
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John, you will get the hang of it.
I certainly can't think of what is causing that problem.
Hopefully some engine guru's can figure this one out.
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| John Coryea |
Posted on 07/17/12 - 5:08 PM
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Thanks Joe-
I was wondering if it could be a sticky/faulty mechanical advance? I had this problem on my MGA distributor one time..
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| contender250 |
Posted on 07/17/12 - 6:16 PM
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John how is your fuel bulb? (only use,replace with a factory one and you need the larger 3/8 with the 120)) also are you running the vro with your unit? Check the gas side of the vro for the diaphragm maybe bad? Check the small filter on the engine also the filter you have installed. What happens does the engine just quit a 2500 rpms? Really just sounds like something simple not getting gas or air causing the engine to quit...Good luck
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| John Coryea |
Posted on 07/17/12 - 7:47 PM
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contender250 wrote:
John how is your fuel bulb? (only use,replace with a factory one and you need the larger 3/8 with the 120)) also are you running the vro with your unit? Check the gas side of the vro for the diaphragm maybe bad? Check the small filter on the engine also the filter you have installed. What happens does the engine just quit a 2500 rpms? Really just sounds like something simple not getting gas or air causing the engine to quit...Good luck
Hello contender-
Yes, I'm using the vro. The small filter is ok. The bulb does not go flat,gets hard when I first pump it. basically, if I attempt to run faster than @2000,2100 , OR less than 3000, it will slowly die within that rpm range..Always starts back up. Sometimes if I'm quick on the throttle back, I can prevent it from dying. Now, if I'm cruising at say 2000,and I boot it to 3000 or more very quickly, it will take off like a rocket. If I try to gradually feed it throttle from 2000 to 3000 it will die. It will run wide open all day if you want to..never dies below 2k or above 3k..
Hope this helps!
Otherwise ,I love this boat! Only one on the lake and it gets alot of compliments.
All the best,
John
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| tedious |
Posted on 07/18/12 - 5:15 AM
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John, thanks for bringing this interesting problem here to WhalerCentral. This one really is intriguing. I'm guessing it isn't the mechanical advance, as I'd think that would affect your top end as well and you say it runs fine there.
How quickly does it die when you attempt to run it in the problem range? Your description of taking off like a rocket when you throttle up makes me suspect it's getting too much fuel in that midrange, so when you pop the throttle open the fresh air straightens out the mixture and you get that burst. If it runs for 20 or 30 seconds or so before it starts to die, that could be it. On the other hand, if it starts to die right away, I am more thinking that the spark advance is mismatched to the carb opening. You said that you did a carb rebuild - that's a full cleaning, new floats, new seat, etc.? Did they also do the link & sync?
Tim
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| John Coryea |
Posted on 07/18/12 - 5:36 AM
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tedious wrote:
John, thanks for bringing this interesting problem here to WhalerCentral. This one really is intriguing. I'm guessing it isn't the mechanical advance, as I'd think that would affect your top end as well and you say it runs fine there.
How quickly does it die when you attempt to run it in the problem range? Your description of taking off like a rocket when you throttle up makes me suspect it's getting too much fuel in that midrange, so when you pop the throttle open the fresh air straightens out the mixture and you get that burst. If it runs for 20 or 30 seconds or so before it starts to die, that could be it. On the other hand, if it starts to die right away, I am more thinking that the spark advance is mismatched to the carb opening. You said that you did a carb rebuild - that's a full cleaning, new floats, new seat, etc.? Did they also do the link & sync?
Tim
Thanks Tim- I know he didn't replace the floats or needles,just cleaned them ,replaced gaskets and seal kit.Hmm.. To answer questions-
It will die within a minute or two entering the problem range.
he said the linc and sync was ok
Another interesting thing.. previously,when it would die,I could catch it if I pushed the primer...now if I do that ,it stumbles..like it's getting too much fuel..opposite of before.. I can run the boat for the rest of the season as is I suppose,and send the carbs off to someone in the fall..I know my riding mechanic is getting expensive!
Thanks for your help!
John
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| tedious |
Posted on 07/20/12 - 5:05 AM
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Well, that's a headscratcher. The only thing I can think of is that one of the carbs has a slightly leaky float needle, so that it seals OK at idle, but once the fuel pump is pushing more pressure in the midrange it shoves fuel past the needle and into the carb throat and motor. And then at high speed, that still happens, but it doesn't matter as the motor is happy to use up the extra fuel. That's all pretty far-fetched and speculative.
I'd certainly try new floats, needles, and seats if they are changeable on your carbs. Kind of a shame your mechanic didn't just replace them while he had the carbs apart as the incremental cost is almost nothing. Also, if I recall correctly, some OMCs had a pulse limiter in the vacuum line to the fuel pump that limits the maximum fuel pressure - you might want to look up whether your motor is supposed to have such a thing, and if so verify it's in place.
Tim
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| tothemax |
Posted on 07/20/12 - 6:53 AM
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I'm not familiar with the Johnson carbs, but from what he is saying it sounds like there is a dead spot and the carbs are starving out.
Pushing the primer would enrich the mixture, goosing the throttle to up the RPM's also hits the accelerator pump adding fuel.
When the carb was rebuilt did the mechanic soak it (carb dip and blow it out). A blocked vacuum passage can cause this, in a car incorrect base gaskets can also affect performance. What is confusing is that this is multi-carb motor - since the motor runs at idle and high speed it would appear that the carbs are working and points to more of a single source issue.
You said the fuel bulb was good and all of the fuels lines \ filters are good no air leaks, I would check the fuel pump diaphram - and all connections for blockage if you haven't already.
This is a real puzzler...
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