1989 Johnson GT150 V6 Throttle Issue?

[jmd143]

Boat setup: 1989 Ranger 360V w/ 1989 Johnson GT 150 V6

So, the last time i was out, I noticed the when I tried to get up on plane, with the hand throttle all the way down (no hotfoot), it stuggled getting out of the hole, which it never used to. Also once i got on plane, at max throttle, i was not getting my max speed, usually around 55 MPH, but was only getting about 45 MPH. I also noticed a different sound, almost as if i was not reaching my max RPMs. It didnt feel like any of the cylinders were missing and last i checked the compression was all even. When I got home I pulled the cowling off I checked the throttle linkage area as my suspicion was that something was binding or preventing me from getting max throttle. when i put the hand control all the way forward to actuate the throttle. the travel in the linkage stopped about a half inch short of the Throttle adjustment screw. Based off the indicator on the adjustment screw, it has not moved. I can physically move the linkage with my hand that last 1/2" to contact the screw, but it does not do this when the hand throttle is actuated.

So my question is, I assume at max throttle, the linkage should touch the screw, and since it is not, I assume that i am not reaching max and that is why the performance is suffering.

I have taken pictures if that helps but i am at a loss for what to do, short of taking it in for service.

[omcforever]

Thats the max timing stop, not throttle stop. Check to see if timer base is sticking under flywheel or hanging on something. Do this by disconnecting it from the the arm/plastic ball assembly and move by hand. If it is sticking, the right way to correct is remove flywheel and remove timer base and clean track it rides in. Some have used a small amount of WD40 on it from the outside but usually doesnt work long. An OMC service manual(not Clymer or Seloc) will show how to do it.

[omcforever]

Your max throttle stop is located at the bottom of the throttle arm that is connected to the cable. It is a 5/16-3/8 jam nut assembly.

[omcforever]

DO NOT TRY AND LOOSEN OR ADJUST THE MAX TIMING STOP!!!! Insure that when the throttle handle is all the way forward that carbs are 100% open by looking at the throttle plates with silencer cover off as well. At that point, timer base should be at timer base max timing stop. Post up what you find,,,

[jmd143]

DO NOT TRY AND LOOSEN OR ADJUST THE MAX TIMING STOP!!!! Insure that when the throttle handle is all the way forward that carbs are 100% open by looking at the throttle plates with silencer cover off as well. At that point, timer base should be at timer base max timing stop. Post up what you find,,,

Not sure if this was the issue or not, but the jam nut on the "cam" system (yellow zinc/gold plate in center of the pic) near the carburetor was loose. When I engaged the throttle fully it didnt look like the baffles would be able to open fully. I didnt take the silencer plate off to visually see this but from the indication on the outside, it didnt look like they were fully open. I readjusted the jam nut and re-tightened so the they should open fully? This is my assumption. What would i expect to happen now that i was going from partial open to full open at max throttle?

I will not be able to get the boat out till sunday to try and see if this made a difference, just wasnt sure what this change would hypothetically do, by opening the carb more.

[Bassmeister]

I know it's a pain with those hundred screws in the silencer plate, but that's the only way to know for sure.....

[omcforever]

I know it's a pain with those hundred screws in the silencer plate, but that's the only way to know for sure.....

You can also check for full opening by looking at the port side of carbs(looking from rear of boat forward) roll pin in the throttle shafts. At full open , they should all be straight up and down when adjusted properly and all open at the same time. Your OMC repair manual tells how to adjust them as well.

[omcforever]

To be safe, a complete link and sync by the book needs done. When ever something comes loose, you rarely get it back to where it needs to be by just eye balling it. That pick up cam adjust looks way off as well. Get it checked.

[Bassmeister]

Listen to omc.....

[316jughead]

Yes you need to do a sync and link, your idle pick up timing could be off. When you advance the throttle with the control handle you will see that the timing lever is advanced with a lever and a spring, sometimes the center of that throttle and timing linkage will bind up, not letting the timing to advance fully. Remove the big bolt and clean and lube with moly lube, the smooth kind. OMCforever is the man on your motor, he won't steer you wrong.