86 evinrude 90 coughs intermittently

Hello, I have an 86 Evinrude 90 that coughs every 2-3 seconds at low speed and stalls at idle in neutral in test tank. Ran great last year. Don't know if the original owner did any carb rebuild. Have replaced all fuel lines, new gas. Traces of white smoke in the exhaust indicate it is getting oil. I understand from the manuf. that this carb has fixed high and low speed orifices; is this correct? Model # CE90TLCDC

Inside the carburetor throats near the top front area, you'll see a small brass jet in each throat. These are idle AIR bleed jets that measure air, not fuel.

The smaller the hole in the jet, the more fuel is drawn to the related cylinder. The larger the hole..... less fuel is drawn by the related cylinder.

Your engine is running lean on at least one cylinder. With the engine running at an idle and this problem taking place, take one finger and place it securely over each idle air bleed jet. When the engine smooths out, you've found the offending carburetor and the exact cylinder that's running lean.

Great diagnosis! Right on the money! Bottom 2 cylinders are the culprits! What is the next step?

Check compression to make sure that cylinders (all cyls) are okay. What are the compression readings? If okay, remove the carburetor, clean thoroughly, and rebuild it using a complete carburetor kit.

Pay particular attention as to what size jets go where..... sizes marked on jets.

Be sure to maually clean the two high speed jets (2 per carb) that are located in the bottom center portion of the float chambers. Fuel must flow thru those jets before gaining access to any other fuel passageway.

The 2 idle air bleed jets in the top front of the carburetor for the 90hp should be part #324025 and be marked with the number 34 meaning that the inside diameter of the jet is .034 in size.

(Carburetor Float Setting)
(J. Reeves)

With the carburetor body held upside down, the float being viewed from the side, adjust the float so that the free end of the float (the end opposite the hinge pin) is ever so slightly higher (just ever so slightly off level) than the other end. And when viewed from the end, make sure it is not cocked.
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