Ignition Switch Voltage

jeffnangela

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Jan 21, 2005
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21
I have a quick question. I am having problems with low voltage to my electric fuel pump on a 454 Marine Power Inboard. I've been through the full diagnostics and have wound up at the switch. <br />My problem is that I have 12 volts at the switch, but turn the key to start and the voltage to the yellow/ red wire that leads though the neutral safety switch and on to the starter relay is only reading 9 volts. I've cleaned the terminals and everything but still only 9 volts. Am I wrong or shouldn't I be getting at least 12 volts like the power (red) wire that feeds the switch?<br />My second question is does the starter relay require a ground? The engine was installed in 2000 after a rebuild and I have found a black ground wire that appears to have rattled loose from the terminal on the starter relay. The problem is that the terminal that appears to have come from reads 12 volts with a meter. According to the engine wiring diagram this terminal should be a ground. Maybe the Marine Power mechanic knew something that I don't about the starter relay.<br />Thanks,<br />Jeff
 

Laddies

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Sep 10, 2004
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12,218
Re: Ignition Switch Voltage

It sound like you need a relay to power up the fuel pump and /or the ign. system
 

Moody Blue

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May 24, 2004
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Re: Ignition Switch Voltage

When you measure 12V at the switch is that with the key off? Are you measuring 9V in the START or ON key position ? I would expect the voltage to drop in the START position because you are drawing a lot of current for the starter motor. If you are measuring less than about 9.5V during starting you should have your battery checked and load tested.
 

jeffnangela

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Jan 21, 2005
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21
Re: Ignition Switch Voltage

9V is measured during start on the yellow/ red (starter wire). The power supply is 12V+.
 

Moody Blue

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May 24, 2004
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3,136
Re: Ignition Switch Voltage

The 9V is a little on the low side. In START position would expect about 9.5 - 10V for a fully charged battery in good condition. <br />What did you mean by "I am having problems with low voltage to my electric fuel pump" ? Does the pump not operate ?
 
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