1999 90HP Johnson Bogs down

[aquaholicjavi]

I have a 99 90HP johnson that its starting to bog down when I begin to accelerate it out of idle. At times I have to do it very slowly and at other times it just dies on me. When the engine is on idle it seems to be runing smooth, and when I get past that initial acceleration it runs fine at top speed too. The problem seems to be happening just to get out of idle. Everytime I take the boat out I feel that the problem is getting worse.

I cleaned all four of my carbs this weekend and set the carb adjustments to 5 3/4 turns from lightly seated. Any other ideas on what could be causing this? Should I play with the needle adjustments on the carbs?

Thank you
Javier

 

[Brew2]

Re: 1999 90HP Johnson Bogs down

Dirty carbs would have been my first guess....when you say "cleaned" you mean removed from engine disassembled and cleaned...not just sprayed some sort of cleaner in them...correct?

If you bump the primer (push in key) a coulpe times immediately prior to accelerating, does the motor "get through" the bog? If so, something is preventing fuel from getting to one or more cylinders. Assuming the carbs are clean, then I'd be looking for an air leak in one of the fuel line connections (including the small lines running to the carbs) or possibly a kink/pinch in one of the lines....make sure the motor hood isn't pinching anything.

Good luck!

 

[aquaholicjavi]

Re: 1999 90HP Johnson Bogs down

Yes, the carbs were removed, dissasembled, cleaned, and reinstalled. They were not rebuild with a rebuld kit, but I didn't think they needed to, the gaskets are in good shape. This is something that I did about 8 months ago, I didn't think it was the carbs but I cleaned them again just to be sure.
I will look for an air leak in the fuel lines, also, could it be something with my spark plugs or fuel pump.
I replaced all 4 spark plugs and cables about 6 months ago when i was having a problem in which I would accelerate the boat fully and it wouldn't go passed 3500 RPM at times. Replacing spark plugs and cables fixed the issue.

Thank you.

 

[Brew2]

Re: 1999 90HP Johnson Bogs down

It is possible that spark, compression, fuel pump could be part of the issue, but if it runs fine at higher RPMs as you noted in the initial post, I'd suspect either an air leak or a fuel line blockage as the most likely issue(s).

Try the "bumping the primer" trick....if it virtually eliminates the bog, then you are definitely looking for a fuel delivery issue.

Have you replaced the inline fuel filter? Also....is there any chance you might have some water in your gas? Put a sample in a clear glass jar and leave it for a while to see if it separates into gas/water.

Good luck!

 

[tashasdaddy]

Re: 1999 90HP Johnson Bogs down

you have 2 fixed jets, and one adjustable, sounds like you did not remove and clean the fixed jets.

http://shop2.evinrude.com/ext/index.aspx?s1=86d3d72aeba35dacbc349b439cb45104

 

[aquaholicjavi]

Re: 1999 90HP Johnson Bogs down

Ok, so I took the boat down to the lake yesterday for some testing and tweeking. I was not able to see any type of air leakage in the fuel lines. When the engine begined to bog down I held the ignition down to choke it and it didn't came out of the bogging stage for a few seconds.
I had the carb needles set at 5 3/4 turns. I played with them a little bit yesterday and opened them about 2 more turns to 7 1/2 or so. The engine ran a bit more smoothly on idle but when I tried to give it gas I can't do it too fast because it will die. I have to bring it out slowely. I don't think I should keep on opening those needles, it seems like they're way too open and it shouldn't be like that. I had the needles set at 6 turns out before I cleaned the carbs and it was running smoothly.
I took it for a run after those adjustments and when I accelerate it, it seems to take a little bit to respond on that initial acceleration stage, it kind of feels like is going to die for 2 seconds but it then comes right out and begins to respond fine.
I believe there is another problem somewhere. What should I do next?

Thanks.

 

[Brew2]

Re: 1999 90HP Johnson Bogs down

I'm not familiar with your carb, however, given Tashasdaddy's description, it sounds like you have an adjustable low speed jet, and fixed mid/high speed jets. If so, adjusting the low speed jet will only impact the idle, not an acceleration bog.

Did you remove and reclean the mid/high speed fixed jets as he suggested?

Also, re bumping the primer...I found it only worked effectively if you bumped it a couple times immediately BEFORE accelerating...not during the bog.

I still think you are looking for some sort of fuel delivery restriction, but you could also check the timing advance under the flywheel to make sure it is moving freely as you accelerate. If it is sticking, it could cause some issues.

Good luck!