Crank but want start Mercruiser 5.7

Wellcraft1996

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Jun 23, 2021
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31
Start here if you dont have 12 v to coil, check the kill switch
I ordered a new kill switch because trying to hold the button down by hand engine would not even crank over. Had to push button real hard to make it engage. So once new kill switch arrive I see if that was the problem
 

alldodge

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Mar 8, 2009
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Need a voltmeter
Bat to starter post
Starter post to 50 amp breaker
50 amp to motor 10 pin
10 pin to 20 amp online fuse red/purple
In line fuse to key
Key to purple
Purple to kill switch
Kill switch to 10 pin
10 pin to coil
 

nola mike

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Apr 22, 2009
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5,407
I ordered a new kill switch because trying to hold the button down by hand engine would not even crank over. Had to push button real hard to make it engage. So once new kill switch arrive I see if that was the problem
There are (probably) 2 "kill switches". First is the neutral safety switch. The motor won't crank if that's tripped. Second is man overboard with a lanyard attached. You'll have your symptoms with this one being bad. Can test voltage on both sides of switch or jump the purple wires.
 

boblane

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Jun 27, 2016
Messages
7
what about running a wire from battery pos term to coil directly?
if you look at wiring diagram the coil gets 12 volts from the purple wire coming from the alternator witch comes from the orange wire coming from the starter.. check if the orange wire and the red/purple wires coming from alternator have 12volt? make sure key is on position
I am sure its something crazy stupid...lol
just take your time look at the diagrams and follow wiring if power goes from battery follow to next item see if power comes out to next thing. Also check all grounds on everything!! if the coil ground wire broke no spark
good luck
 

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alldodge

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No the Orange does not power the purple
The purple is powered from the Key as in post 22
 

Wellcraft1996

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Joined
Jun 23, 2021
Messages
31
what about running a wire from battery pos term to coil directly?
if you look at wiring diagram the coil gets 12 volts from the purple wire coming from the alternator witch comes from the orange wire coming from the starter.. check if the orange wire and the red/purple wires coming from alternator have 12volt? make sure key is on position
I am sure its something crazy stupid...lol
just take your time look at the diagrams and follow wiring if power goes from battery follow to next item see if power comes out to next thing. Also check all grounds on everything!! if the coil ground wire broke no spark
good luck
Hello my friend I ran the wire from the battery straight to the coil positive and the engine fired right up. So what is causing it not to have enough power at the coil to have ignition on its on??
 

nola mike

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Apr 22, 2009
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5,407
Replaced the lanyard emergency switch with a new one.
Dude, you're shotgunning everything. Do some of the troubleshooting, any of the troubleshooting steps outlined above (poor AD's about to have a fit that you haven't done the steps in #22). This won't be hard to solve if you just go in a logical order.
 

Wellcraft1996

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Jun 23, 2021
Messages
31
As Charlie Brown would say GOOD GRIEF
Voltmeter and post 22
Went through every wire connector, wires, fuses and safety switch on my boat. Still no spark, so unplugged engine main harness connector and spread apart all the male prongs, plug it back in and shazam, it fired up.
Thanks for your help
 

boblane

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Jun 27, 2016
Messages
7
just like I said in post#15
I had same problem tried everything then I unplugged the wiring harness and cleaned pins and pow! it works

lol. glad you found the problem
 

alldodge

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Went through every wire connector, wires, fuses and safety switch on my boat. Still no spark, so unplugged engine main harness connector and spread apart all the male prongs, plug it back in and shazam, it fired up.
Thanks for your help
The issue is going thru the wires is not the same as using a volt meter. A meter would tell you if there was voltage or not so you could determine what is the issue. From your statement, the connector was pulled apart and you don't know if it was the Red/Purple or the Purple wire pin which was the issue

Glad your running
 

boblane

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Jun 27, 2016
Messages
7
Hi Bob, which pins did You clean??
disconnected main wiring harness and clean all the pins on one side (try to open the pins a little with small thin screwdriver for better contact) and all holes on the other side I then put dielect grease on them and I had spark again
 
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