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87 351 pcm weak spark from coil

S

Scott Booth

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When the key is in the crank p

When the key is in the crank position there is a very weak or no spark as soon as I move the key back into the run position it sparks. Also at times the engine keeps trying to crank when the key is moved from crank to run.
 
Bad ignition switch. I'd

Bad ignition switch. I'd start there. West Marine sells a nice selection of them.

Jeff
 
I replaced mine with one that

I replaced mine with one that had an accessory spot. That way you can turn on the radio without the rest of the motor being on. Got one for Discount Inboard Marine at a reasonable price
 
"Replaced switch and starter &

"Replaced switch and starter (suggestion of West Marine) still no improvment. Still weak spark, hits when it is moved to run possition. Still sticks in crank. Any idesa"
 
"Some motors I've seen hav

"Some motors I've seen have their ballast resistor circuit wired through the starter motor. To wit:

When you are cranking it the starter solenoid sends a full 12 volts to the 9 volt coil for a hot spark. But when you let go the key, 9 volts is sent through the ballast resistor to the coil.

It's possible that this circuit is messed up some how.

Jeff"
 
"i have a similar problem, bou

"i have a similar problem, bought new coil a few weeks ago (12volt) on the outside of the coil it says use external resistor. so i used the resistor. after a few weeks it got harder and harder to crank for the first crank of the day. then it just wouldnt crank. so messin around i bypass the resistor and bam the thing fires on the first revolution. should i take off the resistor or find out if the coil is just bad."
 
"brad,

if you remove the re


"brad,

if you remove the resistor you can end up frying your coil and/or ignition module depending on your set up. i would make sure you had the correct ballast resistor first."
 
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