470 Starts then Stops

yamhoss86

Petty Officer 2nd Class
Joined
Jul 17, 2013
Messages
116
When i try to start the motor, i hear it start but does not continue to run.
Once in a while when trying to start the motor, the motor starts but struggles to run.
I just installed a new carburetor.
At first i thought it could be bad gas. So i loaded up my 5 gal tank and redirected my gas line to the new gas, still no good start. Then i thought it could be bad spark plugs. So i took my old spark and this is what they looked like ( please see below). What should i check? Should i get new spark plugs?
 

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thumpar

Admiral
Joined
Jun 21, 2007
Messages
6,138
Re: 470 Starts then Stops

Does it shut off after returning the key to run from start? It could be a resistance issue to the coil if so. The coil gets a full 12v from the starter while cranking but then gets power from the resistance side. One way to test would be to run a 12v line from the batter or other 12v source to the coil. Just remember the engine will not shut off until you disconnect that wire.
 

yamhoss86

Petty Officer 2nd Class
Joined
Jul 17, 2013
Messages
116
Re: 470 Starts then Stops

Does it shut off after returning the key to run from start? It could be a resistance issue to the coil if so. The coil gets a full 12v from the starter while cranking but then gets power from the resistance side. One way to test would be to run a 12v line from the batter or other 12v source to the coil. Just remember the engine will not shut off until you disconnect that wire.

Most of the time it does shut off after returning the key, then there are times while it starts but struggles to keep running.
 

thumpar

Admiral
Joined
Jun 21, 2007
Messages
6,138
Re: 470 Starts then Stops

Try running the 12v to the coil + side.
 

stonyloam

Vice Admiral
Joined
Mar 13, 2009
Messages
5,827
Re: 470 Starts then Stops

Could be bad resistor wire connection. Doing as thumpar suggests will tell you.
 
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