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View Full Version : Johnson 90 won't idle, help!


Azeal
04-19-2009, 06:20 PM
I have a 1989 Johnson 90 VRO (still has the vro connected) that I bought last year with my Arima. Always been cold blooded, and the idle was rough, but performed well once warmed up.

Ran it springer fishing yesterday, fine in the morning and throughout the day. Anchored in the afternoon, and when I went to crank it up to pull the anchor, it would start and stay running when revved up with the high speed idle lever, but die whenever the lever was dropped down below 1/4. Ended up pulling the anchor with the kicker. Was finally able to run the big motor back to the dock by cranking it and letting it run for a while with the high speed idle up... dropping it down to 1/4, then dropping it down completely while immediately shifting into gear and revving up with the throttle handle. Not good for the lower unit, but I was a good 6 miles from the dock and low on kicker fuel. Motor performed fine once the RPM's were up, planed the boat just fine and ran normal, cruised at 22 mph or so all the way back to the dock with no hickups. Died as soon as it was throttled down to 1500 rpm or so.

Today I replaced the plugs, the fuel/water sperator, and the fuel line (old one was not in great shape). Did not resolve the issue. Fuel bulb firms up and stays firm. There is some weeping of fuel/oil around the carbs, but this has been the case since I got it (and I've put 60 hours on it since the).

Anyone have suggestions on what else I should look at? And/or a good, affordable Johnson mechanic who knows these old motors? I've love to repower, but I don't have the $$ right now.

Just-in-Time
04-19-2009, 06:47 PM
carbs need a rebuilding

where r u located?


I have a 1989 Johnson 90 VRO (still has the vro connected) that I bought last year with my Arima. Always been cold blooded, and the idle was rough, but performed well once warmed up.

Ran it springer fishing yesterday, fine in the morning and throughout the day. Anchored in the afternoon, and when I went to crank it up to pull the anchor, it would start and stay running when revved up with the high speed idle lever, but die whenever the lever was dropped down below 1/4. Ended up pulling the anchor with the kicker. Was finally able to run the big motor back to the dock by cranking it and letting it run for a while with the high speed idle up... dropping it down to 1/4, then dropping it down completely while immediately shifting into gear and revving up with the throttle handle. Not good for the lower unit, but I was a good 6 miles from the dock and low on kicker fuel. Motor performed fine once the RPM's were up, planed the boat just fine and ran normal, cruised at 22 mph or so all the way back to the dock with no hickups. Died as soon as it was throttled down to 1500 rpm or so.

Today I replaced the plugs, the fuel/water sperator, and the fuel line (old one was not in great shape). Did not resolve the issue. Fuel bulb firms up and stays firm. There is some weeping of fuel/oil around the carbs, but this has been the case since I got it (and I've put 60 hours on it since the).

Anyone have suggestions on what else I should look at? And/or a good, affordable Johnson mechanic who knows these old motors? I've love to repower, but I don't have the $$ right now.

fishkisser
04-19-2009, 07:03 PM
Sounds like a leaky manifold gasket allowing too much air in the mix ...
Thats why you have to add so much fuel to richen the lean mixture to keep it running ...
Replace the carb to manifold gasket and give it a try ...
Sounds like you need a new one anyway ... :twocents:

Azeal
04-19-2009, 10:07 PM
carbs need a rebuilding

where r u located?

Portland, OR.

Picked up a Seloc manual for it today... I've rebuilt motorcycle carbs long ago. Debating whether to attempt a rebuild myself or have a marine mechanic do the honors. $$ is tight.

Just-in-Time
04-19-2009, 10:22 PM
do it yourself

i use a heated ultrasonic cleaner from harbor freight, with just simple green in it

fishkisser
04-20-2009, 09:22 AM
do it yourself

i use a heated ultrasonic cleaner from harbor freight, with just simple green in it

Contact time with simple green and aluminum should be kept to a minimum as it is corrosive to metals and some plastics ...:twocents:

Just-in-Time
04-20-2009, 02:46 PM
i dilute 75 to 1
500 second bath

never failed me yet and is better then any other stuff i have used

lostbackpacker
04-20-2009, 03:45 PM
pm sent

Tinman
04-20-2009, 09:17 PM
Mark at Greg's Marine in Garibaldi is good with old OMCs, and his rates are reasonable. He worked on my old 1986 Evinrude 25, and my new-to-me 1996 Johnson 88 hp.