rough running.

kinson

Cadet
Joined
Nov 10, 2002
Messages
10
hello all.<br /><br />well ot begin with. I have a 65 hp mercury, 650 model. year is from then till now? 4 cyl.<br />and my problems are.<br /><br />rough idle and slow speed but will plane after a couple of minutes. backfire's or coughs when starting. rebuild carbs, wires are good. ok today i was going at top speed or as top as i think it is all of a sudden it power'd down to idle and backfired and ran really rough shaking and all kinds of things. i let it sit for a minute and it started and ran as it usually does (from the top of my post). so any how any thing i should look at and test. have'nt taken out spark plugs yet, what should i look for on those. oh and the plug wire's are numberd 1-4 should they go in order from top to bottom or diffrent. right now their from top to bottom. i dont have a tach so dont know the rpm's. but do know its really bad or low.<br />well anyway thanks to anyone who posts to this topic. oh and what looks like steam or white smoke comes out of the exhaust. also new water impeller. any thing else i missed tell me. ;) <br /><br />and is there a chat on here?
 

scotiany

Senior Chief Petty Officer
Joined
Aug 3, 2002
Messages
749
Re: rough running.

Does your Mercury have combustion chamber breather(drain) valves(reeds) that might be plugged up?
 

rickdb1boat

Supreme Mariner
Joined
Jan 23, 2002
Messages
11,195
Re: rough running.

Sounds like it may still be overheating. Can you hold your hand on the head while it's running. Should be warm, but not so hot as to burn your hand. Check compression to see what shape the Motors in. Who did the Impeller Job?
 

kinson

Cadet
Joined
Nov 10, 2002
Messages
10
Re: rough running.

its not over heating i can put my hand on the head its slightly warm. about the reeds are they right behind the carbs or to the left and right of the intake.?
 

Solittle

Fleet Admiral
Joined
Apr 28, 2002
Messages
7,518
Re: rough running.

kinson - Go to Search at the top of the page and enter a search arguement like "runs rough" or "backfire." I tried backfire and got 200 responses. You may find your answer there.
 

kinson

Cadet
Joined
Nov 10, 2002
Messages
10
Re: rough running.

hey does anybody know a napa part number. for gasket sets for my engine?
 

kinson

Cadet
Joined
Nov 10, 2002
Messages
10
Re: rough running.

i did a compression test and all cyl showed 115. is this good on a cold test couldnt warm it up. any replies would be good
 

rickdb1boat

Supreme Mariner
Joined
Jan 23, 2002
Messages
11,195
Re: rough running.

If they all showed 115 PSI, it's OK. Do you still need the Gasket Kit? If so, post serial #.
 

kinson

Cadet
Joined
Nov 10, 2002
Messages
10
Re: rough running.

the seiral number is 1898487. i dont know the yaer for it. could somebody tell me. im trying to get a manuel without ordering off the net. so if its not the cyl then it has to be in the electical somewher. i guess
 

rickdb1boat

Supreme Mariner
Joined
Jan 23, 2002
Messages
11,195
Re: rough running.

If that is the correct Number it is a: <br /><br />650 (65,0) 1869564 - 2119748 1966 4 cyl <br />Pull the Plugs and see what they look like. That may tell some of the story. The wires go Top to Bottom. So they are correct! What # plugs are you running. Note which cylinder they come from when you remove them and if one or more look much different than the others. NAPA does not go back that far, using that serial #. Post Back on your findings.
 

kinson

Cadet
Joined
Nov 10, 2002
Messages
10
Re: rough running.

all the plugs look the same, white ceremic is brown and the rest is a little black. spark plus is b8S NGK. and i took the points and all that off because when i got the motor took it home there was some blue silicone where someone had sealed it so took it apart and it all looks fine after some clean up. but i dont know what i should look for in it?. thnx for the replies!
 
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