1998 90hp Johnson Optical..."skip" at different throttle ranges.. see video

[jayp0209]

So i have a 1998 Johnson 90hp optical (J90elecm) this "skip" started last season, i put it away for the winter, had the dealer service it in the spring. they thought that the carbs needed rebuilding so they tore them down, rebuilt them. I still have this skipping. they say that it will be a week before they can even take another guess at this.. it starts and idles. SOMETIMES it will "sneeze" at low rpms and stall, not too often though.

I will prime the ball, (sometimes it never gets hard, other times it does) start the boat.. let it idle for a few mins... take off... runs good for a couple mins then after about 4-5 mins of running it will "skip" like the video shows. does it a lot more the higher rpm your going.... if im idling around or going under 3/4k it will run fine for a WHILE.

Carbs rebuilt
New cam rollers
new racor filter
new plugs
pennzoil 2 stroke used
no water in fuel (checked)
premix unit at 50-1

See the video and give me an idea where to go next.. is this maybe a "lean sneeze" or something else maybe?
98 Johnson 90hp optical "skip" while running? - YouTube

 

[Bosunsmate]

Re: 1998 90hp Johnson Optical..."skip" at different throttle ranges.. see video

Re: 1998 90hp Johnson Optical..."skip" at different throttle ranges.. see video

primer ball should always go hard so somethings wrong there to start with.
Might be a coil dropping out, do they look ok?
Any difference in colour on spark plugs?

 

[jayp0209]

Re: 1998 90hp Johnson Optical..."skip" at different throttle ranges.. see video

Re: 1998 90hp Johnson Optical..."skip" at different throttle ranges.. see video

primer ball should always go hard so somethings wrong there to start with.
Might be a coil dropping out, do they look ok?
Any difference in colour on spark plugs?

i will check the plugs tmw and look at the condition of the coil packs.

as far as the primer ball, the ball is new (old one broke when i dewinterized it) i simply cut the fuel lines and stuck a new ball in.. ill replace the lines as well to see if that helps the primer ball.

another note..the fuel tank has a small pin hole leak at the TOP of the tank.. ive epoxyed it but it is having trouble holding... doesnt leak fuel due to its location BUT isnt sealed 100%.. ive been reluctant to replace the tank because i simply cant find that exact tank ANYWHERE.. (doing more research tonight) ...would this contribute to the primer ball issue or maybe the "skip"?

 

[Bosunsmate]

Re: 1998 90hp Johnson Optical..."skip" at different throttle ranges.. see video

Re: 1998 90hp Johnson Optical..."skip" at different throttle ranges.. see video

if the carbs arent done properly the floats wont close off the fuel inlet and so fuel will leak past and the primer bulb wont go hard.

tank hole shouldnt cause you much bother, its just like not leaving the tank lid fully closed. The biggest concern is that something may drop in there including water

 

[jayp0629]

Re: 1998 90hp Johnson Optical..."skip" at different throttle ranges.. see video

Re: 1998 90hp Johnson Optical..."skip" at different throttle ranges.. see video

all 4 plugs look like this... They are not new.. I've used the boat and burned about 40 gallons of fuel thru them... Am I seeing extreme lean condition?

 

[Chris1956]

Re: 1998 90hp Johnson Optical..."skip" at different throttle ranges.. see video

Re: 1998 90hp Johnson Optical..."skip" at different throttle ranges.. see video

It might be running a bit lean. Doesn't look too bad.

BTW - That motor has a vapor separator with a float, inlet needle and seat. If the primer bulb doesn't get hard, the vapor separator could be the issue. I would inspect and rebuild it if necessary.

The video sounded like a cylinder was cutting in and out. This could be due to lack of fuel. Make sure the primer bulb is working correctly, and the fuel lines do not have any air leaks.

 

[jayp0209]

Re: 1998 90hp Johnson Optical..."skip" at different throttle ranges.. see video

Re: 1998 90hp Johnson Optical..."skip" at different throttle ranges.. see video

upon further inspection, there is an air/fuel leak at the top cap of the vapor separator. im going to grab a new gasket and see if this solves my issue.

 

[Faztbullet]

Re: 1998 90hp Johnson Optical..."skip" at different throttle ranges.. see video

Re: 1998 90hp Johnson Optical..."skip" at different throttle ranges.. see video

BTW - That motor has a vapor separator with a float, inlet needle and seat. If the primer bulb doesn't get hard, the vapor separator could be the issue. I would inspect and rebuild it if necessary.

Sorry but VS dont work that way... The float and inlet needle is to open/close vent to vapor pump, if float was stuck down the vapor pump would pump fuel into intake and flood cylinder/s. Make sure you use only a OEM bulb and check the VS top to see if its leaking as if loose/warped/gasket failed the VS wouldnt hold pressure and leak/weep around top. This can cause a lean condition but your skip is electrical. Youmay have a bad wire as these models burn off inside boot sometimes and they must be the grey RFI wires. If wires ok the "eye" or pack is acting up. What is your rpm as I have seen packs bump the limiter and cause a similar issue...

 

[jayp0209]

Re: 1998 90hp Johnson Optical..."skip" at different throttle ranges.. see video

Re: 1998 90hp Johnson Optical..."skip" at different throttle ranges.. see video

rpm is 5600-5800 and it does this between 4000-5800.. its usually FINE right after start up... (choking, high idle and priming) then i drive for a couple mins and it gets worse and worse. sometimes, i will sneeze while idling in neutral and shut off... it also "sneezed" coming off plane the other day (it was acting up the whole ride back) and it shut off when it approached 1500 rpms

i took the air box off and primed the engine.. i saw fuel bubbling out of the cover of the VS.. i replaced the rubber gasket and then ran the engine WOT for about 10 mins and it ran flawless.. so i think i found the issue?

 

[Bosunsmate]

Re: 1998 90hp Johnson Optical..."skip" at different throttle ranges.. see video

Re: 1998 90hp Johnson Optical..."skip" at different throttle ranges.. see video

Sounds like you have,
You should ring the dealer and find out why they didnt find that by doing the tests you did, too often i find they want the massive carb cleaning fee and dont do proper checks first,
might get some petrol money back

 

[jayp0629]

so, i have to bring this thread back to life sadly!!!! ok, so i replaced that gasket.. the boat ran great for about 20 gallons of fuel.. now its skipping again

i rechecked the gasket/cover, no leaks STILL tight.
i swapped the fuel tank, changed the main fuel line, by passed the racor filter and used fresh fuel
changed the spark plugs
ran the boat at night with all wires exposed, no blue electric light jumping around and the wires looked ok
dealer/shop owner/tech watched the video said its NOT ignition that i is fuel, hands down. told me its not the optical eye because it would not run, end of story. not the eye. didnt even want to sell me one. told me to keep looking at the fuel system?

ball is holding a prime now, no fuel visibily leaking and i cant hear air leaking when i prime it.

the boat will run EXCELLENT when trolling or lower RPMs...
i can run WOT for about 2 mins before it give me any "bucking"
if i stop.. shut the boat off for a little while.. restart it will run good for about 2 mins.. then it will "buck" or "miss" at high RPMs

the engine starts right up and idles fine.. VERY rarely it might cough at idle but it does that every 20 or so starts..just once.

 

[jayp0629]

so, i have to bring this thread back to life sadly!!!! ok, so i replaced that gasket.. the boat ran great for about 20 gallons of fuel.. now its skipping again

i rechecked the gasket/cover, no leaks STILL tight.
i swapped the fuel tank, changed the main fuel line, by passed the racor filter and used fresh fuel
changed the spark plugs
ran the boat at night with all wires exposed, no blue electric light jumping around and the wires looked ok
dealer/shop owner/tech watched the video said its NOT ignition that i is fuel, hands down. told me its not the optical eye because it would not run, end of story. not the eye. didnt even want to sell me one. told me to keep looking at the fuel system?

ball is holding a prime now, no fuel visibily leaking and i cant hear air leaking when i prime it.

the boat will run EXCELLENT when trolling or lower RPMs...
i can run WOT for about 2 mins before it give me any "bucking"
if i stop.. shut the boat off for a little while.. restart it will run good for about 2 mins.. then it will "buck" or "miss" at high RPMs

the engine starts right up and idles fine.. VERY rarely it might cough at idle but it does that every 20 or so starts..just once.

 

[jayp0629]

also, carbs are rebuilt!

 

[boobie]

I read through this post and maybe I missed it but did you ever replace the OSI sensor ??

 

[Faztbullet]

" told me its not the optical eye because it would not run, end of story. not the eye. didnt even want to sell me one. told me to keep looking at the fuel system?"
The eyes do get weak but engine usually misses at all rpms,. I have seen weak ones kill the engine when cowling took off on bright sunny day. Also need the grey RFI update wires as pack will pick up RFI interference and act goofy.Also check that the 2 orange wires from power coil are plugged into pack good.

 

[jayp0629]

Ok so I replaced the optical.. Swapped coils and wires. No change.. Ughhhhhh I will never buy another Johnson. Never had issues like this with my merc. What's next?!

 

[jayp0629]

ordered a power pack and coil.. update to follow..

 

[jayp0209]

Power pack solved it.