1999 Johnson 150 Bogs when warm

[MMcrack]

Good morning all! I'll try to keep this as short and to the point as possible while still getting my point across...

I've got a 1999 Johnson 150 that's not given Mr any problems until this season...for some reason when the engine is warm it won't get past 1500 RPM without bogging down and trying to die.

Here's what I've done so far:

-pulled apart and cleaned all carbs and verified bowls weren't warped.

-had a spare VRO rebuild kit sitting around so I changed that.

-pulled apart the vapor separator and made sure the float was set properly.

-my powerpack was acting up last year so I replaced that, cables, optical sensor, and plugs. (Started this season with my old PP, cables, optical sensor, and plugs and it was still doing the same thing)

-verified good compression.

-replaced fuel lines, water separator, etc.

-tested with external fuel tank and new fuel.

-replaced water pump at beginning of season.



I will fess up and say that I have not checked timing and I didn't take apart the vapor separator pump to verify the diaphragm was still good.

I believe it's fuel related simply because I leave the ramp perfectly fine, but once the engine is warmed up the only way for me to get above 1500 RPM and get on plane is for me to play with the throttle and choke. Once it's warm and I come down from being on plane if I sit at idle it'll start to sneeze like it's running lean.

Has anyone ran into this problem or can guide me in a direction to keep troubleshooting it before I burn this beast to the ground?

[omcforever]

Did you replace all seals and gaskets when you went thru everything?

[omcforever]

Did you replace all seals and gaskets when you went thru everything?

Reason I ask is that when ever you re-use any old seals or parts you may create issues that compound what actually is happening.

[MMcrack]

Reason I ask is that when ever you re-use any old seals or parts you may create issues that compound what actually is happening.

Mostly, yes. The only gasket I didn't replace was the vapor separator gasket as it was on backorder. All other gaskets (carbs) looked good, but still got replaced. I see what you're saying though and appreciate the help!

[JoePA]

idle air adjustment screws, what are they at? I think they should be set to 5-6 turns out from lightly seated. clear roller still on the arm that opens the carb butterflies? Link n sync?

[MMcrack]

Joe, thanks for the recommendations. My "idle" screws have always been set to 7 1/3. I have them set to 8 right now because once the engine gets warm it seems to be leaning out and starts to sneeze and the last thing I want to do is run it too lean.
The roller on my butterfly arm is black, bit it's the same as it's been since I got the boat as well.
I haven't preformed a link and sync. I will do that this week as well as check the timing due to replacing ignition components

[MMcrack]

This past weekend I was able to replace the thermostats as someone suggested in another forum. One of them had a piece of silicone in the end of it. Both were dark brown and obviously needed replacing. I took it out after and it did the same thing though. But here's the kicker...when I get it up to right around 3000 RPM I start to hear a knock now. Because I was already on the water I decided to do a little more troubleshooting. My buddy let me borrow a fuel pump that he converted his VRO system to. It's one that bypasses the oil system completely so I took my spare tank with me that had 50:1 in it. Same result.

Still while on the water and frustrated as I could be I decided to take the vapor pump diaphragm off since I haven't taken it apart yet. Once I got it all back together and the stupid hose next to the carb reattached I tried it again... it's better....not fully, but better nonetheless.

So now when I give it balls to the wall power from idle it will still die. But, if I get it up to ~1500 and play with the throttle than it will rocket up to 3000. Oh, and the knocking is still there.. W.T.F. IS GOING ON?!

[omcforever]

Jerry knows these engines well(I dont)..maybe we can get him to chime in. Link and sync/timing def could be an issue. Just remember that if it is a fuel issue and we stay lean bad things WILL happen quick. May have to have a qualified marine tech look it over to be safe.

[omcforever]

Jerry-316Jughead,,,,,,,if he does help, listen and answer and do what he says or recommends. He does not like games or give advice and then do the opposite,,,ect. He is a wealth of info on these engines.

[MMcrack]

I sure hope he does chime in. I'm willing to try anything except throw parts at it to see what foxes it of course. I'm getting a timing light and going to try the Joe reeves method this week as long as do a link and sync. I just want to get it up and running because the offshore bite is hitting hard here!

[omcforever]

I'm getting a timing light and going to try the Joe reeves method this week as long as do a link and sync. I just want to get it up and running because the offshore bite is hitting hard here!

Negative!!!!!!! That motor takes a special way to time/sync. You are getting ready to get into trouble. Either find someone that knows how properly or take to a reputable OMC/BRP tech.

[omcforever]

If you dont really know what you are doing or listen to so called internet tech talk/buddies/you tube/FB ect.....you can seriously damage or destroy your engine. Maybe someone else here can chime in and help/direct you but dont just take shots in the dark. Get a real OMC/BRP manual (not Clymer or Seloc)for your motor and get familiar with it.JMHO

[omcforever]

What kind of boat is it on and what is your operating rpm range??? You do spin it up to 5000-5500?

[omcforever]

Model Number Please.

[MMcrack]

You are right. My apologies as I didn't read further into the manual about the OIS system not being able to be correctly timed with a light. I saw it in the manual and then got sidetracked before I started reading the steps. Have no fear though, I'm smart enough to read it through before I start something.
Boat is a 1998 19ft sea era center console. Normally at WOT it'll sit at ~5200.
Model number is J150PLEES.

[MMcrack]

I found 316Jughead 's ebay store where he sells the ignition analyzer. Heck of a price too so I ordered one and will set/verify the timing once I get it. Probably needed it anyways because I have never checked that since I got the boat years ago.
And as far as knowing what I'm doing goes, I'm very mechanically inclined. A few contracts in the military working on jet engines will do that to you. But I always like advice from people that know more than me or have already gone thru my same problems. Save us all time and makes connections.

[ChampioNman]

You do need the clear sleeve on the roller, the timing and throttle needs to come on at the same time no delays.