why does my ignition fuse keep blowing

2002 CHEVROLET SILVERADO
185 MILES
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GREGNICHOLS
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It started as a fuel filter problem.After getting fuel flowing,every time I turn the ignition,the starter turns engines and then the 40amp ignition fuse blows. Any idea why?
Aug 11, 2012 at 1:07 AM
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GREGNICHOLS
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Turning to start. Motor begins to turn over and then fuse blows
Aug 11, 2012 at 1:11 AM
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KASEKENNY
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There are a number of things that can cause this however, I have seen this a number of times. The issue is most likely a driver circuit that is shorted, and it only turns on when cranking the engine or it is running.

This means it is either a coil, injector, or even a starter.

So, the most likely of these is a coil. I would suggest disconnecting the coils one at a time and crank the engine. When the fuse stops blowing then that is the problem coil.

Here is a guide that will help with this testing as well:

https://www.2carpros.com/articles/how-to-test-an-ignition-system

Next, we need to do the same thing with the injectors. If all this checks out, we can move onto the starter.

However, please let me know what you find. Thanks
Feb 17, 2022 at 6:09 PM
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GREGNICHOLS
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Checked grounds, replaced fuse and relays. I disconnected the ignition coils one at a time and found #3 was shorted you were right I wish I tried that early. DOH, I love this site.
Feb 17, 2022 at 6:09 PM
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KASEKENNY
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That is great news. Thanks for the update and for letting us know what ended up fixing it.

Please come back to 2CarPros next time.
Feb 17, 2022 at 6:10 PM