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please help!! Mercury thunderbolt ignition 85hp

T

tambo rebel

New member
hi i recently purchase a boat with a mercury thunderbolt ignition 85hp outboard. it seems to turn over ok but it hasn't got spark:confused: so it won't run:mad:.
and i am also not sure if it is a 2 or 4 stroke.
so if you can help me it would be great.
 
Welcome to the forum.Post the number,it'll be on a plate on the transom bracket.Post a pic or two. If you are going to work on it yourself,I suggest you get a manual.This site does them,http://www.marineengine.com/manuals/seloc/mercury.html .
Why no spark? There is a mercury tilt switch,disconnect it and try again.Disconnect the kill switch,black/yellow stripe.Try again.If not,then the switch-box is probably shot
 
Look for a black/yellow stripe wire,kill switch,it will be around the same place,disconnect it.And if you still have no spark,it's probably your switch-box/power pack. If you post the number,we'll know for sure what year/model we're looking at.Is it a distributor or multi coil motor we're looking at.Coil for each cyl.
 
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I am quite sure that this motor is a 2 stroke.----But you could look for a dipstick / place to add oil / place to drain oil from the powerhead to be sure.
 
this is a picture of the engine. i cant find the black/yellow wire boat engine.jpg
 

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There will not be a black/yellow wire on this outboard.It looks to be '71/'72.Is there a number on the starter bracket?
As that's the starter side,I'll assume there is a distributor on the other side,going by the switch-box.The square box with the colour coded terminals in front of the starter.That is probably fried.The main reason this gets fried is someone has connected the battery assways,or disconnected the battery while the engine is running.
 
do you know of any websites that sell this model switch box? and what type is it?
[h=3]CDI Switch Box[/h][h=3]Sierra Switch Box[/h][h=3]Mallory Switch Box[/h]
 
You need to submit a photo of the other side, where the distributor is. IF it's the usual, battery powered ignition model, then there are lots of good, used switch boxes for those on eBay. (You MIGHT have the rare Lightning Energizer distributor, however. Need to see a photo to be sure.)

When we figure out which ignition you have, I can give you the correct part number to use while you're "shopping".

Jeff

PS: It's a 1973 to 1975 model that had either type distributor.
 
fastjeff said:
PS: It's a 1973 to 1975 model that had either type distributor.
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That is correct.:eek: I was thinking Merc800
The missing wire is the brown which is now attached to the rectifier for the tach signal.Modern tachs take the sig. from the stator wires at the rectifier
 
The 850 Never used the energizer of the 500 or 650 they used battery cd until 1976 then went to ADI the 800 used 2 different CDI systems one was called the blue coil, which was really bad, and the other just before upgrading to the 850 was back to the CDI similar to the inline 6...... Dean Evans
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http://johnsoldmercurysite.com/phpBB3/viewtopic.php?f=17&t=3452
Before you buy a switchbox check to see if distributor belt is broken and not turning distributor.
The square box with the colour coded terminals in front of the starter.That is probably fried.The main reason this gets fried is someone has connected the battery assways,or disconnected the battery while the engine is running.
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It the box that craps if battery reversed and trigger that craps when disconnected when running....
 
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