2004 Johnson 90hp Johnson 2-stroke surging at 3/4-full throttle

[gam3cocks]

Hey guys. Finally made the boat purchase and it has the 2004 Johnson 90 stroke.

Long story short, it ran flawlessly for 2 straight days at all throttle levels then I went out last night and as soon as I got past 1/2 throttle, about to get on plane it would bog up and down. Kind of tough to explain, but it would lose power then quickly regain, jump forward for a couple of seconds then shoot forward again. They boat is in the water and will be for the nxt couple of weeks so any work that I do will have to be in the water.

Here are some tidbits that may or may not help.

• fuel not getting to the motor, IE bad fuel pump??
  
  • Don't think that this is it, the problem still happened when I manually primed the bulb.
  • Quick side bar, once I get going, the bowl does not stay hard. It doesnt get squishy or flat, just not hard. I have read conflicting statements on what is correct??
  
  
• Fuel filter was replaced when I bought the boat. Same with gearcase oil
• took off the cowling and there were no leaks that I could see. With that said, it did appear to have some greenish substance on the inside bottom of the cover but not much at. Looks to be just oil run off or it hasnt been cleaned in a while.
• Coil Packs or power packs??
• Bad fuel or low fuel? Gauge doesn't work. Going to put 10 gallons and fuel treatment in this afternoon.
• When I got on the boat last night, the access plate for the gas filler was randomly off?? not sure why. Very odd. It did pour yesterday. Anyway, when the access plate was off, I noticed 3 tubes. one not being connected to anything. It wasn't a thick fuel line, therefore I didnt think much of it. Now I am thinking it is a breather line that should be connected to the Perko Filler cap??? I will look at this more today.

Anyone have a clue?? I am a novice when it comes to outboards and I really dont want to throw random parts at it. Wow. Sorry for the long post.

[gam3cocks]

Oh and to add to this. It does take a good minute or two to start when it is cold....After it runs, it starts like a champ

[ChampioNman]

Is the VRO pump still operational? Just asking about that because you mentioned the third line being disconnected and it may be the oil line or it could be as you say the vent line also. Access plate for the fuel filler randomly off?? As in the gas tank cap off?

[gam3cocks]

Sorry about the confusion. VRO pump is still operational.

Where the 3rd line was "disconnected" was literally right off of the Perko fuel filler in the side of the gunnel/hull. That is where the access plate was off. See the crude image below where is says "fill line" and "ground". That is where that same access plate is and I can see the Perko gas filler and 3 total lines. One large rubber fuel line, a smaller rubber line, then a mystery 3rd plastic ribbed line. What I was referring to as being disconnected was the 3rd plastic ribbed line. It could be and is probably nothing.

[ChampioNman]

Grab a clear container and remove the fuel line to the filter on the motor, give the bulb a few squeezes to put some fuel into the jar and let it settle for a few minutes. If you have water in the fuel it will settle to the bottom.

[gam3cocks]

Will do that tonight. Anyother simple things like this I should/can try? I will try to take a bunch of photos tonight

[ChampioNman]

When you pick up your primer bulb, pick up a real BRP primer bulb yours will be a 5/16" size bulb.

[gam3cocks]

Are you saying when I check the fuel for water I will need to get a new bulb?

[ChampioNman]

no not at all, you don't have to replace the primer bulb if you don't want to that is only a recommendation.

[gam3cocks]

Ok, thanks for the help. I went down last night, and it would even fire up this time. I did check the water in gas and there was none. I did find some oil/fuel mixture in the bottom of the cowling so that leads me to believe that there is a leak somewhere. I am just going to call a mobile mech to come take a look. If it was out of water, I would feel more comfortable doing stuff myself.

I did take some pictures but it just looks like a motor, I doubt you can see much from them but let me know if you want me to post them up.

[ChampioNman]

Sure post them up we love pictures.

[gam3cocks]

Here ya go!

[ChampioNman]

Couple things I see first one is the throttle roller is missing the clear sleeve on it I've circled it in yellow.


Next one the hose circled in yellow, I believe is the vent hose goes to the bottom corner of the air box. Hard to tell in you picture.

[ChampioNman]

Part number for the roller is 0432639.

[gam3cocks]

Your a champ! thanks man! I will double check what that tube it.

Having htat sleeve off, what would that do?

[gam3cocks]

No that I think about the random tube, I don't think that its the one from the airbox. I made a point to zip that that one down last night. Gave me a fit putting that airbox in.

Now that you mention it. Would tthere be any reason for fuel to be in/around those 4 rubber sleeves?

[ChampioNman]

Your a champ! thanks man! I will double check what that tube it.

Having htat sleeve off, what would that do?

Engine timing and throttle bodies won't open at the same time. This will give you performance issues and not let the throttle plates open fully.

[ChampioNman]

No that I think about the random tube, I don't think that its the one from the airbox. I made a point to zip that that one down last night. Gave me a fit putting that airbox in.

Now that you mention it. Would tthere be any reason for fuel to be in/around those 4 rubber sleeves?

Look at the port side balance tube, there is a hose that comes out of it and goes into the airbox. More that likely it's fuel draining out of the carbs from the motor being tilted up. That hose has to go somewhere and it isn't toward the rear of the motor.

[gam3cocks]

Ah perfect. yeah I will look into that little tube. I will double check on where it starts and where it is supposed to end.

That makes sense about hte motor being trimmed up.

[RI_Bred]

I'm having a similar problem currently with my 2005 90hp carb'd Johnson outboard...just had my mechanic out with me yesterday on the water to troubleshoot. I drove the boat while he was on the motor. He first checked for spark while underway by pulling each plug wire to see if the cylinders dropped out each time (they did). This ruled out electrical. He then turned his attention to the carbs, and figured out that both starboard side carbs were not getting fuel. At least one of my plastic float bowls is slightly warped, and I've had that issue in the past. So could be a combo of sucking in too much air and / or a clog in the carb jets or stuck needle or whatever...regardless, I ordered four new bowls and carb rebuild kits. Hopefully that does the trick. I learned a lot watching him diagnose it, worth the price of admission (he's a legit marine mechanic doing work on the side). Let us know how it turns out! Dave