I’ve started having an issue with my Johnson. I have an idea of what may be going wrong but wanted to get some interwebz opinions.
model: J90PLEEB
The last time I checked compression was this time last year and it was nearly perfect +/- 120 on all holes, minimal variance. It is always run on either RiversEdge ethanol free fuel or e-free from the V-Go on Savannah Highway next to Doschers. Even with e-free it still gets stabilizer most of the time. I burn Penzoil in it.
Over the past year it has run perfectly. No stalls, no hesitation of any kind, just perfect. For about the past 4 weeks now, when cold it starts up fine runs for 20-30 seconds and stalls. Restart it and it’s good to go and would idle all day from there on. My start up procedure doesn’t involve a high idle or anything like that. Give it a choke to fire up and let it warm itself up at idle. It is smoking a little heavier in recent weeks than it has been previously.
At the very beginning of the day, it seems to be missing when running over 4000 RPMs. But after I get to my first location and stop, then restart to go somewhere else it runs perfect the rest of the day.
My routine: get to the marina and load the boat. Fire up the motor and let it idle to warm up while I return the dock cart and finish putting stuff away and getting ready to run. Once warmed up a good bit, idle out of the marina. Get on plane and run to my first spot. For this past weekend, that was from RiversEdge to the harbor running 4-4500 RPMs. The entire was running fine, then thump/miss, run run run, thump/miss, run run run run run, miss miss miss, run. It’s generally just one miss at a time but at one point it missed a couple times in a row. I fished for a couple of hours and idle around some creeks and whatnot. Come time to run back to the marina the motor is cold again, but doesn’t have any of the miss for the rest of the day. This is typical of what’s been happening the past could of weeks.
Yes I do have a Racor. No it hasn’t been drained or replaced this year.
Forgot to mention. It has new plugs (approx. later half of July) and thermostats are from approx. November/December. Everything on the boat is new as of last fall. Boat was completely refit with the exception of replacing the tank (poly) and motor itself.
My first guess with the old OMC smokers is nearly always carbs. But, here…
This time… my first guess will be a coil getting flaky. A flaky coil could have a temperature dependent fail. When it gets hot, it opens up. When it cools it returns to normal. This is very hard to confirm as long as the miss is intermittent.
That having been said, I’d always drop that spin on fuel filter and replace it if is anywhere near a year old. Examine the contents before you trash it to see if it has captured any water.
17’ Henry O Hornet w/ Johnson 88 spl
26’ Palmer Scott project hull
14’ Bentz-Craft w/ Yamaha 25
I am due to change the filter. But I really don’t think it’s the problem. It is a clear bowl Racor and there are zero signs of water in it visually from just looking at whats in the bowl.
I replaced both coils, all 4 plug wires, and put on a fresh Racor. It felt livelier, as it should with new coils and plug wires. But my problem is not solved. The problem exhibits a little different symptoms now. Previously when it missed, it a was a very sharp thump of a miss. After installing new coils, wires, and fuel filter, it was more of a bog sensation. But would only miss after running over 4500 RMPs for more than say 2 minutes.
Andy; know the feeling. I am having a problem with my Johnson also. it is not getting used and the outlook is not good. ha ha ha hope you get that motor problem figured out soon.
My Johnson works great. I wash it real good every day, drain the water off a couple times a day and the wife gives it a workout several times a month. It works great always starts right up and never stalls.
Loopervet’s suggestion of the power pack has fixed the issue. He had a used one on a parts motor and allowed me to test it out, then come back and buy it from him after we had the results. Saved me about $140 over ordering a new power pack. Thanks for your help Sean!
The one that came off my motor looks perfect. Except maybe a little wear on the connections and rubber boots from the power pack to the coils. The one off the parts motor looks rough (dirt dobbers) but has better feeling connections and makes a more solid connection to the coils. Guessing the one that came off my motor will go just fine again if I were to redo those 4 connectors to the coils.
