Skip to content

Johnson gt150 1990 idling issues.

Featured Replies

Anyone ever rebuild the carbs? Or any experience with this motor, it won't idle for long and will stall out, making docking/ loading it a pain with a constantly stalling. New vro pump I put in and the problem was there before this. Thinking the carbs might be gummed up and the idle seems high. I've rebuilt my dirt bike carb but it was 4 stroke, could I tackle this on my own? 

  • Super User

They are about the easiest carbs on the planet to clean a build.  One big plate on top comes off and the whole fuel path is laid out in front of you.

You do need to get a manual and go through the synchronization though, that's probably off.  Also, there is a cam system on top of the motor that operates the crabs.  The roller on it is bad about coming apart and the outer piece missing.  Look at yours and see if there is just a black piece sticking up about 1/4" in diameter, if so, you need a new roller.  It should have a clear looking outer shell over the black and should be about 3/8" in diameter.  If it missing, it will throw you sinc off.  

Also, once you got through and get the sinc right, paying careful attention that all marks are hitting dead on, and all three carbs or opening at exactly the same time (very critical so get them right), do not adjust the idle speed with the linkage stop.  Also, make sure they butterflies are fully closing at idle.   You adjust the idle with the timing rod on top of the engine going back to the timer base.  In other words, your idle is adjust by timing not throttle linkage.  This does not affect WOT timing, so don't worry about that, there is another stop on top of the engine that adjust that. 

I guess I should have also said, you still have to pull the bottom off to get to the float, needle and seat, etc to check those and set the float level.

  • Author

Awesome think about a day to clean and rebuild? 

  • Super User

I hope you understood, before pulling the carbs, I would get a manual and do a link & sinc.  There's a good chance you might not need to pull the carbs, just get them adjusted a balanced properly.  But then, what the heck, if something ain't broke, just keep working on it until is broke.

  • Author

I picked up a monometer so well see this spring after ice out!

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Unfortunately, your content contains terms that we do not allow. Please edit your content to remove the highlighted words below.
Reply to this topic...

Recently Browsing 0

  • No registered users viewing this page.

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.

Account

Navigation

Search

Search

Configure browser push notifications

Chrome (Android)
  1. Tap the lock icon next to the address bar.
  2. Tap Permissions → Notifications.
  3. Adjust your preference.
Chrome (Desktop)
  1. Click the padlock icon in the address bar.
  2. Select Site settings.
  3. Find Notifications and adjust your preference.