40 hp merc , help please!

[tri-hull guy]

hi , i just got a 40 hp merc and it doesnt want to turn over for a compression test. I tried with a key and just heard a click, starter didnt move. so i said ok ill just try and pull sart it, well it pulled but it was really hard to pull and it was kinda jerky like you could feel the pistons when they drop. the motor was sitting for 2-3 years so i dont even know where to start . any ideas?

 

[305AP1]

Re: 40 hp merc , help please!

hi , i just got a 40 hp merc and it doesnt want to turn over for a compression test. I tried with a key and just heard a click, starter didnt move. so i said ok ill just try and pull sart it, well it pulled but it was really hard to pull and it was kinda jerky like you could feel the pistons when they drop. the motor was sitting for 2-3 years so i dont even know where to start . any ideas?

i would drop a little 2 cycle oil into the cylinders and work the cylinders back and forth very slowly.. other then that i dont see much room for anything esle but a rebuild.

 

[oldman570]

Re: 40 hp merc , help please!

Take all the spark plugs out and shoot some automatic trans oil in the cyclenders. then turn the motor over by hand and see if it frees up some then. Leave it set for awhile if it dosen't want to turn freely, and let the trans oil soak the piston rings for a day then try to turn it over again. Make sure the motor is in Netural while doing this. What year of motor do you have?
Oldman570

 

[Moody Blue]

Re: 40 hp merc , help please!

I'd pull the plugs and spray/squirt a bunch of oil into each cyl being sure to coat the entire cylinder. Leave the plugs out and leave the ignition OFF. Put the motor into neutral.

Slowly by hand, turn the motor over. It should spin freely. If there is still a lot of resistance you may have a problem.

 

[tri-hull guy]

Re: 40 hp merc , help please!

thanks guys, managed to get it turning over and its reading a 140 lbs in each cylinder. next problem it turns over but wont fire up. i noticed some gas coming through an old line going to the bowl. could this be the culprit? spark plugs look clean but havent been used in years, could that be it?

 

[aussieflash]

Re: 40 hp merc , help please!

Next thing to do is check for good spark.Also clean up all wiring,grounds etc.(especially to starter).Then check all fuel lines.Clean/service carbs as per manual/spec and reset float heights to exact spec.Merc service Manual is a must.Post serial # and someone may help you locate manual.

 

[Moody Blue]

Re: 40 hp merc , help please!

A little more info about the particular motor will go a long way in getting good answers to your question. There are many years/models of 40hp Mercs.

 

[tri-hull guy]

Re: 40 hp merc , help please!

sorry bout that its an 83 40hp merc serial number 7186740. im relatively handy but have not had much experience with small engines is this stuff i can most likey do myself? trying to save money.

 

[carholme]

Re: 40 hp merc , help please!

It is a Canadian built engine (starting with s/n 7) and is a model:

1040522 MERCURY 1982 40

Parts listing:

http://www.crowleymarine.com/mercury-outboard/673.cfm

Service Manual P/N: 90-42794-1 for s/ns: (C) 7169338 and Above

Though I prefer the Merc manual above, here is a condensed version of the Clymer manual which should help you get started:

http://web.ebscohost.com/serrc/pdf?sid=4f39f58f-6390-46ec-aa2c-61da882b2095@sessionmgr4&vid=4&hid=10

Download to your computer soonest as the link does not remain active for very long.

Gerry

 

[tri-hull guy]

Re: 40 hp merc , help please!

thanks alot, im glad to hear finally a definitive answer of what the motor was. Aussie what are floats you speak of?

 

[carholme]

Re: 40 hp merc , help please!

He is talking about the carb floats as you will see on page 2/14 of the service manual. Read the section "Fuel System" and figure M10-3 is applicable to your s/n.

Gerry

 

[tri-hull guy]

Re: 40 hp merc , help please!

ok so i manged to get the motor to fire up today but only under the power of quickstart, i replaced the lines that were leaking and its a brand new hose from the gas tank. does this mean the prob is the carb? if so how do i clean it? can i do it while its onthe motor? im trying to avoid taking the carb right off if possible as i would have to remove alot of the engine to get at it. also how do i know what way to turn the idle screw or even if i have to? should there be gas coming out of one of the jets in the throttle body?

 

[Moody Blue]

Re: 40 hp merc , help please!

Whoa, not a good idea to use starter fluid. There's no lubrication in it. It's recommended that you use premixed gas in a squirt bottle instead.

It does sound like you have a fuel delivery issue. Could be a defective fuel pump or gummed up carb. Have you checked that you have gas at the carb.

The only proper way to clean up a carb is to take it completely apart, soak it in cleaner and blow it out with compressed air. Some think that spraying carb cleaner into the throat of the carb is good enough, but actually has little if any affect. There are various small passages that can be clogged up. The float needs to be checked for leaks and the needle valve and seat should be changed.

 

[tri-hull guy]

Re: 40 hp merc , help please!

im not really sure what im looking for to make sure if the fuel is getting in the carb but it seems to be making it through the lines and filter when i pump the ball.looks like the whole motor has to come apart, i hate when they cover things in a motor you know will have to be removed art some point. ill have to take half the motor off just to get the carb.

 

[carholme]

Re: 40 hp merc , help please!

If you don't want to remove the carb yet, disconnect the line going to the carb from the fuel pump. With someone to crank the engine for you, hold the disconnected line into a container and examine the fuel flow to ensure there is a good pulsing flow. This will at least ensure the fuel pump is working OK.

As it sounds like this engine has been sitting for some time, you are going to have to do the carb at some point.

Gerry

 

[tri-hull guy]

Re: 40 hp merc , help please!

well i took off the carbs last night and besides a little gunk here and there it didnt seem to be too bad, at least i wouldnt expect it to be the issue.i used carb clean in all the ports and holes just in case. i know the lines dont have blockage because when i pump the ball the gas flows to the carb fine. so im going to check the fuel pump today but if that isnt the problem i dont know what is. everything seems to be good expect its not firing. could the gas or air mix be a little off or something?