Re: only 3800 RPM at WOT - loss of power under load -- please HELP
Prior to beginning the carb re-build please review the post below sent to me by Joe Reeves. You will find it very helpful and my keep you from having to do it twice or 3x like yours truely. Some of it is specific to my engine but the general info. will pertain to all. I would like to put emphasis on the "clean all orifices with a wire or whatever it takes". All of the jets and ports, and orifices. Gunk won't leave by itself.
Dennis.... All of the jets and passageways pertaining to fuel are conmmon to the high speed jet as fuel must pass thru the high speed jet before it can travel to the other areas.
In the above, I say pertaining to fuel due to the fact that the jets that are installed at the top front area of the carburetors at a angle are "Air Bleed" jets that meter air, not fuel. However, since the air being metered is mixed with the fuel, those jets could also be considered common.
On the 1988 90hp Evinrude/Johnson, the jets are as follows:
Idle Air Bleed Jets (4) = Screwed in at an angle in the top forward portion of the upper carburetor body = .034 (Marked as 34)
Intermediate Speed Jets (4) = Screwed in straight down in the float body = .026 (Marked as 26C)
High Speed Jets (4) = located in the center bottom portion of the float chamber = .056 (Marked as 56C)
I'd suggest that you double check the locations of all of the jets. Also, if you didn't actually clean the high speed jets with a piece of single atrand steel wire, do so as merely soaking them in solution and/or blowing them out with air doesn't do the job thoroughly.
Note that simply blowing a carburetor out with presurized air does nothing to a fouled carburetor. That one small bit of gum causing a restriction will absolutely resist any amount of air you could apply to it.
(Carburetor Cleaning)
(J. Reeves)
If you do not have a regular carburetor cleaning solution container, a very reasonably priced one can be found at many automotive type stores. Should there be a "Advanced Auto Parts" store near you (Formerly Discount Auto), they have a one (1) gallon container (resembles a one gallon paint can) that contains the carburetor cleaning solvent and it even contains a parts basket. Last price I saw on that item was only $10.00 and was under the "Gunk" brand name.
Remove and dismantle the carburetor completely. Remove any rubber, plastic or nylon parts that may be attached to it as cleaning solvent will attack that material. Clean the carburetor thoroughly, not only soaking it in the solvent, but also cleaning it manually wherever needed with whatever tool or piece or wire etc might be required. Solvent alone, although it does a great job, sometimes doesn't get it all. Check your parts manual closely so as not to miss various parts that might create a problem..... such as the small nylon bushing/bearing that exists on the tip of some slow speed needle valves.
Use a complete carburetor rebuilding kit when assembling the carburetor. Using old gaskets etc is a no go unless they were recently purchased and a second look, double checking ones work is in the process.
Carburetor kits usually come with extra parts that would pertain to other carburetors and not necessarily to the one being rebuilt. This is just common practice by manufacturers too eliminate the need for numerous kits..... a keep it simple thing. Simply don't use what you don't need.
Core plugs are included with most kits BUT they don't necessarily need to be changed. Keeping in mind that there are usually a group of exit holes under those core plugs, a rule of thumb is if air can flow thru the passageways and you can feel the air coming out the exit holes under those core plugs, it's generally okay not to change them. The exception would be if you can see a bit of some kind of debris hanging down thru one of those holes, then obviously the core plug needs to be removed regardless of the air flow.
Changing a core plug. Keeping in mind that the critical carburetor casting is not too far beneath that core plug, USE CAUTION in removing it! Drill, or by using a sharp pointed scribe of some kind, create a small hole in the core plug, then insert that scribe or a tool of your choosing and simply pry the core plug off BUT DO NOT insert that tool too far so that it contacts the carburetor casting. To install the new core plug, sealer is usually not needed, simply lay the core plug in its seated area, then tap the center portion of it with a rounded flat proper size punch. This causes it to spread out sideways which seals and locks it into place.
A final note........ Do not ever use any kind of sealer on a carburetor OR anything pertaining to the fuel system. The exception might be an external core plug whereas one could use a substance called "Gasoila" if one thought air might be escaping into the carburetor via its edges.
http://stores.ebay.com/Evinrude-John...tc?refid=store
Hey fellow father, I have 5 kids at home and re-built the entire engine last year and the carbs 10 days ago. The only issue was that my wife began to think I had a mistress name Evin Rude.
