Top 20 Seloc Mercury Outboard Engine Repair Manuals SEC-1416 1990-00 2.5-275 HP Questions & Answers

Not much on that model, but you need a Service Manual. https://www.google.com/search?q=mercury+40+elpt+service+manual ..

I believe that motor has 3 carbs and the one feeding the #3 plug could be running too rich. May need adjusting or rebuilding.

a lot of the temp sensors you add on can not be wired to the temp alarm sensor. you will need a little bracket that bolts onto the head and holds the sensor next to the head. I would put to in the middle of the head to get the best reading.

It is likely to be the opposite and be fuel starvation. Check the following; The tank vent. The pump bulb is the right way around, ARROW towards Engine. Cut a section of pipe and see if the inner lining has delaminated. The grey fuel pipe is bad for this. Modern Ethanol fuels damage the lining. Black Tube is best.

lack of fuel flow not advance on ignition blocked main jets

If the trigger is not working it will not fire.. the trigger is kinda like a set of points in an older engine...tells the ignition when to fire..

0.45L / 0.48Qt 10W30 FC-W There is also a sticker on the spinstarter

https://www.manualslib.com/

Box clogged?

With the info provide, sounds like you still have a bad solenoid.. 1. Take your battery to a battery shop and have the cold cranking amps checked.

https://www.marineengine.com/newparts/part_details.php?pnum=MER47-42038Q02

http://www.marineengine.com/boat-forum/showthread.php?293968-Head-gasket-tight-sequence-and-torque-specs

cylinder head bolt first torque 19 nm , second 37 nm and 3rd 90degree

when an engine stalls or looses power at high rpms , it is because there is a higher need for fuel to supply that requirement fuel shortage can be from blocked filters low float levels in the carby/s vent problem in the fuel tank/s perished hoses letting in small quantities of air the hoses failing intrenally and blocking off the fuel flow pump problems from bad diaphragm or the rubber in the hose again blocking the main jets in the carby/s another area to be checked is the ignition system being able to provide the spark at a higher rpms this problem can be from failing condenser, ignition module or coil/s

water can get into the engine oil from several points if the engine has a sump oil cooler hen the cooler coil wil be cracked or corroded at the seal points more likely the housing behind the water pump has corrosion in it behind the impeller and water pressure is making it leak into the sump

Remove the carburetor and thoroughly clean all of passages by compressed air you probably have blocked passage for fuel on the low idle side

Go to boats.net - Mercury parts - search under hp/serial range - select 20hp 2 cylinder - it will be under the first selection 0A730007 and up.

check the impellor ! which outboard motor do you have ?

Have to take off gearbox,trm tab must also come off and look for nut inside vavity

Check your fuel line really good it sounds like you have a pin hole in your line and it's loosing it's prime