Mercruiser 470 Starter solenoid/electrical issue

[Flyer9113]

Boat engine was running great. Then I heard a buzz and the electric died to the motor and the dash gauges. I traced it back to the solenoid. Power in from the battery no volts coming out when key is turned in the ignition. If I jump the battery wire to the S terminal, starter engages.

i bought a new solenoid. Hooked it up exactly how the old one was. Then when I connected the battery the starter immediately engaged without the key in the ignition. I unhooked all wires to the ignition switch and it still did it. Then it stopped doing it and it is the same problem as before.

I think the new solenoid May have been bad when I got it.

​​​​​​​any ideas?

 

[Scott Danforth]

first, your power to the dash doesnt involve the starter solenoid. it goes thru the large circuit breaker, then to the large plug and up to the dash.

loosing power to the ignition and the gauges is either a loss of power from the motor to the ignition switch at the helm, or a loss of power after the ignition switch to the gauges and engine ignition

jumpering S to B on a starter will make the starter engage. no rocket science there, thats how it works

so start tracing the power

do you have power at all times to the B terminal on the ignition switch yes or no? if no, go back to the motor and look at the big circuit breaker or the connector

if you do, then turn key to run, you should have same voltage on the I terminal (purple wire) if you have any voltage drop, you may have a bad ignition switch. you should not have any voltage on the S terminal (yellow wire with red stripe) until you turn the key to the "start" position

then that wire goes thru the neutral safety switch to the pilot relay on the motor to the solenoid on the starter.

the pilot relay then takes 12 volts from the B terminal on the starter and jumpers it to the S terminal on the starter.

the I terminal (also known as R terminal) on the starter then provides 12 volt power to the coil only during cranking

grab the factory service manual and start tracing the wiring.

 

[Flyer9113]

Thanks for the detailed reply. It is a pretty embarrassing answer for what happened. I checked all the fuses before I replaced solenoid. I re-wired part of the dash last summer. Ended up taping an in-line fuse to the ignition switch so I missed it during most first look through. Replaced fuse everything works.

engine didn’t want to start though when I fixed it. Can replacing a solenoid effect timing? Engine seemed like it was out of time when it almost started. I replaced the points with an electronic ignition last year and it was timed and worked great. Battery might also not be charged enough so we will see tomorrow.

thanks for the help.

 

[Bondo]

Can replacing a solenoid effect timing?

Ayuh,...... Welcome Aboard,...... Nope, that has no effect on the motor's timin',.....

 

[Scott Danforth]

make sure you check for spark. if you replaced your points with a pertronix, i believe that step 8 or 9 still says to keep your points handy for backup.