79 merc 140 cant get no spark

S

sgtmotor

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Sep 8, 2009
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2
help please,
i have a 79 merc 140 given to me and doesnt run. They had the carb rebuilt at a shop and the boat was parked for a year. i wasnt getting any spark from coil or at plugs and replaced coil and resistor. to me the plug wires didnt look like they are in firing order and when i took the caap off the small wire from neg side of coil to distributer was hooked to resistor. does some one know the correct firing order and the correct way the wires hook up in the distributer. thanks for your time.
 
C

Chris1956

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Mar 25, 2004
Messages
28,838
Re: 79 merc 140 cant get no spark

You need to look up the year of that by serial number at maxrules.com. Your description does not match a 1979 Merc 140HP motor.

On a '79 Merc, the distributor cap is labeled for each spark plug wire. The negative side of the ignition coil is grounded, and the positive side of the coil has a wire from the switchbox.
 
S

sgtmotor

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Sep 8, 2009
Messages
2
Re: 79 merc 140 cant get no spark

i was able to finally get spark { the wireing and plug wires all ran wrong}and had to redue the float in the carb and the boat runs fine now. the trim/tilt goes all the way up and down but i noticed the wires i guess go to the sensors outside have been burned up for awhile. i was woundering does that only work the gauge on the dash and do i have to replace it all wires and sensor. thank you for your time
 
C

Chris1956

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Mar 25, 2004
Messages
28,838
Re: 79 merc 140 cant get no spark

Merc Inlines of that vintage do not have trim sensors. They also do not have any warning systems. They do have a trim limit switch on the starboard trim bracket.

You might look up serial number at maxrules.com to get year and then look up parts lists at crowleymarine.com by year.
 
Don S

Don S

Honorary Moderator Emeritus
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Aug 31, 2004
Messages
62,321
Re: 79 merc 140 cant get no spark

and had to redue the float in the carb and the boat runs fine now.
Click to expand...


Just a guess here, but were you referring to a Mercury outboard motor, or a Mercruiser IO?
Both have 140 hp engines. But the IO has a single carb.
 
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