Evinrude 40 HP Carburetor Help

[THE GRAPHICS MAN]

I'm New to this forum but I hope someone can help, I have a 1987 Evinrude Outboard 40 model E40TLCUD my problem is I would like to get rid of my fixed idle air jet carburetors and replace them with idle adjust carburetors, The carburetors I have are junk, Does anyone know if I can replace mine with newer model carbs any help would be much appreciated.
Thank BILL

 

[racerone]

If in Canada------evinrudeparts.ca-----Good help there.

 

[Crosbyman]

that basic design (other than needle adjustment & knobs) has been around your half a century. what issue did you have with it ? The side idle channel leading up to the drip chamber under plug #5 is critical for proper iddling ... did you inspect and clean it and blow dry it ?

 

[racerone]

He said previous owner was " club fisted " and destroyed the carburetors.------He is looking for replacements with adjustable needles.-----I believe there is nothing wrong with fixed jet carburetors.----Owner should check everything before spending beer tokens on replacements.

 

[THE GRAPHICS MAN]

Carburetors apart when I got the motor rebuilt both carbs new everything including all orifices, Carbs were dip and cleaned engine stilled ran bad no idle , Told to try several things one is To determine which carburetor is bad have the engine running at the problem rpm and stick a couple fingers into the carburetor throat (acting as a manual choke). When the engine smooths out and the rpms increase, you've found the offending carburetor, Which is what I did and rpms increased, 2 is remove a spark plug wire which I did and this is what happened, At idle removed top spark plug wire and engine stopped running removed bottom wire engine continued running, Then I switched carburetors ( bottom to top and top to bottom) Pulled top plug wire engine continued to run pull bottom wire engine stopped running. And yes I removed 2 5 and 9 was replaced with a new orifices the top carb works, This looks like a bad carb to me
OK - Here's what I've done.
- Kitted the carbs & fuel pump
- Replaced all the fuel lines with clear ones can see good fuel flow.
- Link & Sync'd As best I know how.
-New spark plugs .040 gap)
- Tested spark (good 7/16 or better arc)
- Compression check =140 psi top and bottom.
I'm complete done with the carbs and basically I would like to switch to the carburetors that have a idle screw and are new or find a good one that I can use
Thanks BILL

 

[Crosbyman]

I did not assume previous owner messed them up.
so twice removal of the bottom plug killed it ! with either carb :-(
tried .030 gaps ??

did you test bottom plug firing.... with an in line spark tester ?

carbs are just metal holes and float .. not much to go wrong if you have new clean orifices. any chance crankcase "pull in vacum" on the lower carb is weak due to vacum loss ?

thousands of those carbs are surely working fine and did not benefit from your retrofit...

up to you.... but I would keep searching for "a" problem external to the suspect carb (s) ... patience brings joy.

 

[THE GRAPHICS MAN]

At idle removed top spark plug wire and engine stopped running removed bottom wire engine continued running, Then I switched carburetors bottom to top and top to bottom) Pulled top plug wire engine continued to run pull bottom wire engine stopped running, Y would it do this if there was something wrong with the power head, I'm not a genius with 2 strokes I'm just guessing at this But I through each cylinder was separated from each other one carburetor and one set of reeds to feed each cylinder. Hope you can help I was going to get a carburetor but can't find one, There's one set on ebay but $390. dollars is a little high for a test .

 

[racerone]

A good set of carburetors should be easy to find.-----Your location ?

 

[Crosbyman]

the engine sucks " idling" fuel from the bottom of the carb bowl via a very small side channel leading up to that drip chamber under plug#5

make certain you have the proper gasket to accomodate the side channel feed route because some "similar" gaskets (depending on the kit) do not have that critical hole punched out.

next is the carb top portion ...if you look real close into the side channel you will see a fine hole which must be clear to allow fuel to reach the top .

make certain you can blow carb cleaner into it and have it come out into the drip chamber on top ....under plug 5 (while it is out) .

with the throttle plate shut at idle it is the only way fuel will reach inside the crankcase ...and cyl. .

Since one carb works all the time (top or bottom) we can assume crankcase vacum is good both in the top half and bottom half of the crankcase.

I may be obsessed but I still think the bad carb can be fixed.
if you have to and they can be switched.... switch the tops between carbs and see what happens.

if the problem moves the top is faulty ... if not check the bottom half of the failing carb.

 

[Crosbyman]

 

[THE GRAPHICS MAN]

I'm a little confused There is a small brass tube inside a large brass tube and the small tube leads up to the carburetor at 2 is this brass tube supposed to be open and the large tube stops at about 3/16 of an inch into the carb and it is clear, I can't blow air through the small tube even with my compressor set at 40 lbs , I'm so confused I do appreciate all your help Thanks BILL

 

[racerone]

Fuel needs to go up the small brass tube.

 

[THE GRAPHICS MAN]

Fuel needs to go up the small brass tube.

That tube is plugged big time, I ran a wire down the tube and it will only
go maybe 3/4 of the way down don't no how I can open it, The tube is plugged bad ( I think we found the problem, Now how to unplug it I will work on it and let you no Thanks BILL

 

[Crosbyman]

great find... looking at that drawing It did not show that brass tube

the side channel route used for ages does not seem to used on this carb if an internal feeder tube is used to route fuel to the upper LS jet and drip chamber.
In any event I think you are on the way to happiness

start by just soaking it or warm it up gently DO NOT ENLARGE or damage it in any way. slow and easy does it!

Keep us posted !

 

[oldboat1]

If you have the carb model that came with that motor (pictured), I would remove all non-metal parts and soak top and bottom in lacquer thinner overnight, then follow cleaning instructions above. A dedicated carb cleaning kit might be a good investment (eg. https://www.amazon.com/gp/product/B072JVQ5DT/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1 ). But use carefully. Work on the blockage you found after a good soaking.

 

[THE GRAPHICS MAN]

When soaking do I need to remove throttle arm I don't no if there's any rubber o ring in there, I looked in the hole on top of the carb but it's hard to see down that deep even with a magnifying glass and a light stand, It looks like the idiot that had his hand on the carb before I got this project tried to remove the brass tube I'm not Sure, If no O ring on throttle I will soak, Let me no what you think.
Again Thanks for the Help

 

[Crosbyman]

I don 't see orings in the parts layout above.

which hole ?? on top of the carb did you look down in ..... is it below the #2 lead plug...I do not think that lead plug should allow you to "see" down the carb otherwise the carb would suck air and null out the idle circuit functions on the carb !!


previous owner may have removed the original plug and stuffed in something afterwards blocking any fuel flow up the carb ??...

can you post pictures inside and outside the carb ...worth a thousand words sometimes

 

[Crosbyman]

see diagram... see parts 6 and 9 #6 is called " fuel nipple" and obviously it must pass fuel #2 lead plug must be in #9 idle jet must be clean . I never saw a par16 on older carbs so this newer e carb body was molded for it ... it is all in your hands now

 

[Crosbyman]

ok found this utube... fuel nipple is just an inlet nipple....nothing to worry about see video
of the 88 40hp carb probably identical to yours the top idle jet is actually for AIR not fuel !! I learned something today

 

[oldboat1]

When soaking do I need to remove throttle arm I don't no if there's any rubber o ring in there, I looked in the hole on top of the carb but it's hard to see down that deep even with a magnifying glass and a light stand, It looks like the idiot that had his hand on the carb before I got this project tried to remove the brass tube I'm not Sure, If no O ring on throttle I will soak, Let me no what you think.
Again Thanks for the Help

sounds fine. ( I leave linkages attached).