Johnson 250 hp Oceanrunner - Does this engine run smooth enough? See video

[adg]

I had trouble last year with the motor not running as it should. Turned out to be the filter/separator that was full of dirt and contained quite some water. Changed that and now it is running much better. But how smooth should a v8 run? How could I improve it further. I am not a mechanic and wonder if there are any easy tricks to try. Any ideas? Hope you can check the video, appreciate your input.

https://www.youtube.com/watch?v=Z8FPFT-WvPE

 

[daselbee]

Re: Johnson 250 hp Oceanrunner - Does this engine run smooth enough? See video

No, I don't think that is running right. Lots of surging, popping, it seems. The video is hard to comprehend exactly what is going on... I think you have ignition troubles, in that it seems to be firing at the wrong time and/or misfiring. First, check each plug wire with a spark air gap tester for spark that jumps 7/16 in. Check each plug wire with a timing light, look into the light, and observe for missing and erratic flashing. Then, you could also index the flywheel and check each cylinder for proper spark at the proper time. Search this site for how to index the flywheel.

 

[adg]

Re: Johnson 250 hp Oceanrunner - Does this engine run smooth enough? See video

Daselbee thanks for feedback. I will start with the spark tester and then follow through as suggested (if i can manage). To be continued next week (travelling).

 

[adg]

Re: Johnson 250 hp Oceanrunner - Does this engine run smooth enough? See video

UPDATE: OK, before I started with testing physical components I thought I would give a fuel additive a try - I used Red Line SI1. I disconnected the fuel hose from the main tank and used a separate jerrycan with fresh new fuel and the additive. Ran it for about 25 minutes. Imho it seems to be getting better and better. I still wish to do the physical checks too but think this looks very promising for starters. See video attached, comments?

https://www.youtube.com/watch?v=TA7wZCpcL2M