Problems with 1985 Johnson 70 VRO

[silverblur]

Help!

I have an 1985 inline 3cyl Johnson 70 VRO. The motor does not seem to be firing on the top cylinder. When the boat is running on the rabbit ears it runs rough and when I remove the top cylinders spark plug with (with plastic plyers) no change in how the motor runs! When I remove the the middle or bottom spark plug wire the motor immediately stumbles and will stall.

With the breather box removed from the carbs if I hold my hand over the throat of the top carb (to rich up the mix & pull gas into the carb) the motor seems to pick up and run smoother. As soon as I move my hand back to running rough.

This leads me to think the motor is NOT running on the top cylinder. Soo I have tried the following....

1) Checked compression

Top Cylinder 135
Middle Cylinder 132
Bottom Cylinder 130

Seems OK

2) Checked the spark on the top cylinder. Spark looks strong.

3) Swapped coils, spark plugs, spark plug wires Individually (no change) Top not running, middle & bottom run fine

4) Removed top carb and cleaned (no change)

5) Changed fuel filter (no change)

Other information:
The motor was a VRO and the VRO is sealed off.
The Engine has sat for ~ 6mos and had water in the gas. Used fresh gas in a new tank for test and diagnosis.

All I can think of is perhaps the reeds/cage for the carb is broken.

Any advice of ideas to try will be greatly appreciated.

Thanks

[ciguatera]

I had a evinrude 60 86 model and had the same problem. Mine was the bottom cylinder doing the exact same thing. Vro disconnected. I changed all the plugs, thoroughly took off the carb and soaked it in carb cleaner and cleaned the jets with wire while also checking if the float was stuck cause 2 days after seafoam shock it started sneezing. Borrowed another carb from a leftover engine and cleaned the carb even better. Now she runs smooth. Not super smooth but it'll do. Check out marineEngine.com and post a question there. They are a bunch of wizards.

[silverblur]

Ciguatera,
Thanks for the feedback, I am hoping someone will have an idea to try. Failing any other ideas I may break it down and re-clean it (maybe rebuild it)

[Mac25]

top carb restricted, if cannot clean then replace! period.

[noelm]

they are a pretty simple engine, I kind of doubt that you will need to replace the carby, but who knows, are you sure you swapped the coils and stuff correctly? it is a simple thing, but you may have missed something, what does the top plug look like when removed? is it different to the other two? start at the very simple trouble shooting before you go throwing parts at it.

[Jim_Arndt]

Good troubleshooting, your diagnosis clearly indicates no fuel to the top cylinder. Another check is to pull all three plugs after letting the engine idle for a few minutes. If the bottom two look wet, and the top plug is dry this further proves no fuel.
Rebuild the carb, get three carb kits and rebuild all three while you are at it. That's the quickest way to kill a 2-stroke is a stuck carb. A stuck carb means no oil to that cylinder. Don't run a 2-stroke if it's running rough, verify it's not a stuck carb first or you will score that cylinder.

[silverblur]

Yup, The carb needed to be rebuilt. I cannot telll you waht was wrong, the carb rebuild kit is very simple for these carbs and the old parts looked like the new parts (I had cleaned them the day before). But for what ever reason the rebuild did the trick.

Thanks for all of your help and feed back!

...................................rb

[Mac25]

your welcome, glad its going.