about 20psi at idle (warm) and 40 to 50psi at 2000rpm.
jerking speed 40 50
The idle screw on a 1981 40 hp Mercury outboard engine is typically located on the carburetor, near the throttle linkage. It is usually a brass screw that adjusts the idle speed of the engine. To locate it, follow the throttle cable to the carburetor, and look for the screw that can be turned to increase or decrease the idle RPM. Always consult the owner's manual for specific details and adjustments.
On metric gauge 2.5 to 3 bar, about 40 to 45 psi. At least 15 psi, 25 psi would be better, 40 psi on a good engine.
Sounds like the Idle Air Control valve.
10w/40
Minimum spec at a warm idle is about 12psi. Normal is about 30 at idle. Should go 40-60 at 3000 rpm.
Around 40
Around 20 psi at warm idle, about 40 - 50 at speed. Should be the same for both the M998 series with the 6.2 naturally aspirated engine and the M1113 series with the 6.5 turbodiesel.
The engine computer is the voltage regulator.
I have a 1974 Chevy truck with the 350 V8 and the engine is in good shape. At idle the oil pressure is 35-40 PSI, at driving speed it goes up to about 50 PSI. Hope this helps.
Very normal for an engine with this mileage. Sounds like the engine is in good shape.