No start weak spark! 502 EFI issues again....
 

I can hardly wait for the day when this engine runs properly.....
Story goes like this:
Last run out I was idling at the dock. Engine dies does not re-start. When I put it on the hose at home it fired but then died soon after. Took it home changed the ICM thinking it went bad again. Not the case. Plugs were fouled so I changed them and check the spark. I have a yellow spark coming directly from the coil. Changed the plugs which did have fuel on them so I know the injectors are working.

Next issue: I also get a voltage drop when I try and start the engine. It will set the alarm off like I just turned the key on as the engine turns over. I did hook up my car with jumper cables to my battery but I guess if the battery is bad this probably doesn't do anything right? IF the battery is bad will it cause weak spark or could it be the coil?

Thanks for any help guys.

A bad battery will cause a weak spark condition on efi/mpi engines.

yellow spark usually = bad ignition coil..check the spark at the coil and not the plugs..if its still yelloy then its a bad coil,,you can match it up with a gm truck coil at napa..same chit but painter with epoxy which makes them over heat..

Put a new battery in and that wasn't it. New coil was not it either. I will be changing my ground cable to a new one. Do you guys ground the block with 2 cables? one on each side of the block? What gauge wire should it be?

You really only need one ground cable to the block. If you have 2 batteries, you can just connect the grounds on them.

I would check and clean all of your wire connections for the ignition.

Thicker the better. 1 or 1/0 is good for about 150 amps.

For anyone seeing this thread it turned out to be a bad battery

Thank you for fallowing up. Well at least a bad battery is a ez fix. Hopefully you didnt have to much takin apart

Wasn't too bad but I did put in new thicker cables as well. Thanks for the help guys!

...so was it a bad original battery or a bad new battery?