88 90HP Johnson rough idle AT WTS END...HELP

[johnnyvv2003]

Hopefully sombody can help me on this one. I bought a boat with a 1988 90HP Johnon on it. It was not kept very well and had very bad gas in the tank. I rebuilt everything in the boat and installed new tanks fuel filters, lines etc. The boat was running fine and then some of the carb cleaner I put in dislodged some muck. The boat lost all high end. I rebuilt the carbs (they were very clogged up), new floats, cleaned the jets and air orifices. Installed new wires and plugs. Now it runs clean at high RPM but idle is like the engine is fighting itself and barely runs, misses and spits.

I am at a total loss after taking the carbs off 4x. There are only 2 carbs that have absolulty no adjustmnets on them.

Questons:
1. How do you adjust the mixture on these carbs?
2. Larger jets are in the bottom and smaller are inside the bowls? (just checking to make sure I put it together right)
3. Floats are set level with the carb body with about 7/8 travel. Correct?

Any help would be great. I am at wits end with this engine. I have never rebuilt arbs and had tehm run worse!

HELP PLEASE!

Johnny

 

[tashasdaddy]

Re: 88 90HP Johnson rough idle AT WTS END...HELP

you have 2 jets 9 and 15 9 is low speed jet, 34 is the air mixture for idle. also you had a clogged high speed jet, did you think to clean the pickup, in the bottom of the bowl, that goes to the low speed jets? http://shop2.evinrude.com/ext/index.aspx?s1=bf6ad09c53cead335fcfd8a6471c0f7f

 

[johnnyvv2003]

Re: 88 90HP Johnson rough idle AT WTS END...HELP

Thanks for the reply. In the diagram it looks like #3 and #13 are the jets. I cleaned all of those out plus every pickup and opening I could find. I dont see any 34 in the diagram for a 1988 90 HP. How do you control the mixture?
SO how do these carbs work?

http://shop2.evinrude.com/ext/index.aspx?s1=bf6ad09c53cead335fcfd8a6471c0f7f

You are correct. When I opened up the carbs it was the high jet that was clogged, but now that everything is clean it is worse at idle. Do these jets wear? should they be replaced?

 

[tashasdaddy]

Re: 88 90HP Johnson rough idle AT WTS END...HELP

you have 3, 13, 7 i think 7 is your problem. no mixture control on that one, fixed jets.

 

[ezeke]

Re: 88 90HP Johnson rough idle AT WTS END...HELP

You don't control - they are all fixed jets and there are two for each carb shown as #3 and #13, one of each for each cylinder.

You can see the air jets #7 so I don't know why in the world anyone would take them out unless you thought they might be the wrong ones (and you could check that without removing them) - no fuel passes through them.
#7 is the jet called a #34 = .034". part # 324025.

What you want to do is to be sure that the two carburetors are perfectly synchronized so that the throttle plates are opening and closing together at the correct time.

 

[johnnyvv2003]

Re: 88 90HP Johnson rough idle AT WTS END...HELP

Thanks for the help everyone. That was exactly the problem. The screw holding the linkages moved when I was rebuilding the carbs. The bottom carb throttle plates were open slightly more thatn the top so the top and bottom cylinders we trying to run at diffferent speeds. One quick adjustment and it idles perfectly.

Thanks again!