voltage drop while cranking

[joseph1980]

I've had an intermittent issue with my boat not starting. I think i've narrowed it down to this, looking for ideas on where to look. The voltage going to the coil (purple wire) shows to be 12.5 volts with the key on, while cranking the voltage will drop to 10.2-10.4. would this be causing the starting issue? I replaced the ignition switch, which has made no difference.

 

[Alpheus]

Re: voltage drop while cranking

Voltage is always going to drop when you are drawing that much current while starting.

What engine are you talking about?
What symptoms are you experiencing?

 

[Robbabob]

Re: voltage drop while cranking

Check your battery with a load tester. Having the 12.5 without load sounds good, but the drop to 10.2 sounds like the battery is toast.

If you can jump start the boat, check the voltage coming from the alternator to confirm.

Good Luck!

 

[joseph1980]

Re: voltage drop while cranking

its a 2000 mercruiser 3.0 liter. I have an intermittent no spark issue. (as tested with a spark tester that will light up when it sparks)

 

[joseph1980]

Re: voltage drop while cranking

have tried a different battery that i know to be good with no luck, the saftey kill switch has been bypassed also with no luck.

 

[Aloysius]

Re: voltage drop while cranking

If you have solid state ignition pick-up, if it doesn't see full (12V) voltage, they won't trigger properly.

 

[joseph1980]

Re: voltage drop while cranking

i know i have the delco est system and i was thinking it also would need the full 12v while cranking. I've also removed the gray wire from the tach and it made no difference.

 

[Alpheus]

Re: voltage drop while cranking

Watch this video. It will help you find out if you have a problem with your wires or connectors. You can check any wire using this method even the starter wire.

http://www.youtube.com/watch?v=v0THDAS1nws

http://www.youtube.com/watch?v=OIRnZNrBOw0&feature=related




I just went out to my boat and checked the voltage drop at my battery and at the coil while the starter is engaged. For the first second it is about the same voltage that you are showing...






.

 

[joseph1980]

Re: voltage drop while cranking

lol thanks for the help but those videos just throughly confused me