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No Spark

J

jlusive425

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I have a Merc 850 with no spar

I have a Merc 850 with no spark. I have checked and am getting power through the stator and both battery and key power to the switchbox but nothing is coming out. I think it may be the switchbox but have also heard it could be as simple as the mercury switch. Any ideas?
 
"James, I assume that this mot

"James, I assume that this motor is a distributor ignition. You said you have +12V to both the red and white ignition wire on the switchbox, right? If so, you need to do the distributor trigger test.

Disconnect the battery. Remove the three wires that go to the distributor. Connect the brown and white terminals on the switchbox, that went to the distributor, with a thin jumper cable. Now connect a jumper cable to the black terminal that used to go to the distributor. Now put a timing light on the thick coil wire that runs to the center of the dist cap. Now reconnect the battery and turn on the ignition. Every time you touch the jumper on the black terminal to ground, you should get a spark on the coil wire. If you get this spark, the switchbox, coil and wiring are good, and the trigger is likely bad."
 
"Thanks Chris, I actually took

"Thanks Chris, I actually took a look at it today and played with the mercury switch, and now it's starting up right away both with the merc switch and without. It was kinda like tapping a bad starter?

I've had the boat stored with the motor in the up/trailering position, is it possible something may have stuck? Anyway, I do plan on doing complete tests as time allows. Thx"
 
"I am having a spark problem t

"I am having a spark problem too with a 1978 Mercury 1150. After looking at the Clymer manual it says there is a mercury switch that is supposed to be connected to the brown contact o the distributor side of the switch box. If this isn't there would that cause no spark? And where would I find one??
Thanks,
Eric"
 
OK I am lost. Where is this tr

OK I am lost. Where is this trigger located?? Green wire from Switch box to coil zeros out the volts when I touch it with pos lead and ground with neg lead of multi meter.
Red and white wire to switch box both have 12 volts. I am new to this type of ignition and am getting frustrated!! Please help me!!
 
"The trigger is within the dis

"The trigger is within the distributor (the 3 wires coming from dist. to box). The mercury switch simply grounds out the box if the engine is tilted, thus cutting spark. You can disconnect the switch and it should spark, if that's the issue... the green wire to the coil should provide positive power to the coil."
 
OK if that is bad. I have to r

OK if that is bad. I have to replace the whole distributor or can I just replace the "trigger" with the 3 wires ?? Kind of like points??
 
"Eric, I had thought that 1977

"Eric, I had thought that 1977 was the last year for the distributor on inline six motors. If you have a dissy, you have a '77.

The trigger is part of the distributor housing, and not seperately replaceable. They are available on the web for ~$200 for new. Rebuild triggers are also available. A lot of folks go with used parts off eBay. I have one on my blown '77 merc 1500."
 
"OK One more question, the wir

"OK One more question, the wires on the distributor cap are the replaceable or do they come with cap?? And if the one from the coil to center of cap is broken will that cause entire system even coil to have no voltage??
Anyone wanna buy a project motor?? LOL"
 
"the wire from the coil to th

"the wire from the coil to the center of the cap is the one that carries charge to distributor for distribution to spark plugs via spark plug leads.If this wire is broke, no spark."
 
"Noel, You are correct. Eric

"Noel, You are correct. Eric the wires unscrew from the distributor cap. You can get new ones at Vintageoutboards.com They are $6 each, which is the best price I found. The coil to dissy lead may be a dealer item. BTW the dissy cap is $100+ to replace"
 
Rectifiers are part of the bat

Rectifiers are part of the battery charging system and on todays modern motor have nothing to do with making spark.
 
The ignition gets it power sup

The ignition gets it power supply from the stator and the spinning magnets on the flywheel.The battery only turns the motor over.Much like your pull start lawn mower it does not need a battery to run.
 
"If this is a distributor type

"If this is a distributor type motor , it gets its power through the battery when the switch is on. It won't run without battery, the stator only supplys ac voltage through a rectifier to keep battery charged. check voltage on white wire on the side starboard where you see the 4 wires, there should be voltage when the key is on. If you still have a problem, no fire go to the trigger side and check by checking as previously discribed from other post."
 
Hey Folks!!! Just an update!!

Hey Folks!!! Just an update!! I have spark and a well ruinning 1978 Mercury 1150 !!! I do have some questions about the water pump / Impeller ???? Does it pee out water through the top only at idle?
 
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