wiring problem 485 mercruiser

[chris mig]

So I have a 485 merc 1982, in a 1988 marlin. I have a single wire alt tied in at the starter solenoid, I did some rewiring and all was great till today. The motor would start but die as soon as i released the key. My issue is that i dont know the correct wiring schematic for this boat.I think i need to do a slave solenoid, there was a seperate one and the starter one was just jumped out, not done like the schematic shows for the original 1988 version. I am beyond frustrated with all this had to get towed in, thank god i renewed my seatow account. So my question is do i need the slave solenoid and where do I tie in the single wire alt, and what does anyone think happened that it would want to start but not run. Any help will be greatly appreciated

 

[alldodge]

Really don't like one wires but that was not your issue

The below schematic is for the 485 with an amp meter. Note there are 2 wires going to the + side of the coil. The purple comes from the starter solenoid which powers the coil when starting. Once started and the key is released to RUN, then power comes from the crab thru a resistance wire which lowers the voltage a bit. Your problem should be in the resistance wire

If unable to replace the resistance wire, you can get a ceramic resistor and make up new wire to feed the coil once started

 

[chris mig]

OMG thank you all dodge for your reply. So where would one find a resistance wire or ceramic resistor, is there a rating on the ceramic or wire. Could this be purchased at a auto parts store? Also i do have the solenoid wired like this schematic but there are 2 more wires at the battery connection on the solenoid i am using the one on the starter, i did away with the one on the block. Also would like to add that i have converted the distributor to a pertronics

 

[alldodge]

Also would like to add that i have converted the distributor to a pertronics

This needed to be in the first post, it changes things.

With the Pertronics ignition then the resistance wire is no longer used, the Pet gets full 12V full time.

You want the purple coming from the 10 pin connector going direct to the coil, no resistance wire.

Also i do have the solenoid wired like this schematic but there are 2 more wires at the battery connection on the solenoid i am using the one on the starter, i did away with the one on the block.

Please explain this a bit more, what was added and what was removed?

 

[chris mig]

well the pet ignition has been in for a few years now and as i recall it was wired up by directions with the resistance wire, i just came back in the house from opening up the wire harness to inspect the resistance wire and it looks fine, but i understand that may mean nothing. As far as what was added and removed I removed the solenoid on the block and used the one on the starter, the one on the starter was simply jumped out, it was not the orignal

 

[alldodge]

Not fully understanding, but you need a voltmeter, and connect it to the + side of the coil and see if there is 12V when key is ON (run position). Then turn to start and see if there is 12V.

If 12V when staring and not in run then the key switch is either bad or the wire or connection feeding the coil is

 

[chris mig]

ok will do that tomorrow AllDodge, but with the key in the run position and testing the power at the coil, should it be less than 12 volts,because of the resistance wire?

 

[alldodge]

ok will do that tomorrow AllDodge, but with the key in the run position and testing the power at the coil, should it be less than 12 volts,because of the resistance wire?

Yes, just trying to find out what is or isn't present

 

[chris mig]

Ok thank you so much for your time, I will check that tomorrow first thing and post my findings....thank you again

 

[chris mig]

So I only have 1.7 volts at the coil coming from the resistance wire and the same at the purple, i checked to see what was coming from the key on the run tab and had 12.7 and also checked thru the breaker and had the same. So i think you got me on the right track but it is way to hot to tear into the harness right now i will do more investigating when its cooler....any tips on where to start

 

[alldodge]

Trace the purple at the key to the coil there is a break or bad connection. The 10 pin motor connector is where I would start

 

[chris mig]

i was thinking the same but how does one test a plug if it is un pluged
i do not want to probe the wire unless i have to

 

[alldodge]

With an ohm meter
Connect to a pin then connect the other end of the meter to where the wire goes.

Example
Purple wire on key switch to pin 5
Pin 5 on motor side to coil/choke

 

[alldodge]

The 485 didn't come with a man overboard kill switch, but if someone did add it, then that will kill power on the purple wire

 

[chris mig]

OK not sure why i did not think of that...duh I should know better. The ohm meter, no man overboard kill switch.This sucks that i wont be able to check things out until Wednesday evening. Thanks again AllDodge

 

[chris mig]

Hi AllDodge so it was the purple wire at the motor plug. I cut and spliced it and tied in directly Thanks so much for all you do here on this site

 

[alldodge]

Thanks for letting me know I got one right :thumb:

 

[chris mig]

yeah so now the oil pan has a pin hole leak....found one on EBAY....gotta yank the motor, which i was going to do just to paint the oil pan before it got a leak at the end of the season :lol::lol::lol:

 

[alldodge]

The BOAT word, never ending hole