1973 mercruiser 120 HP no spark

[rloucks3]

I have a 1973 mercruiser that I changed the trim motor from a single solenoid to a double solenoid the trim is working but I am not getting any spark and I am lost.

 

[alldodge]

I'll assume you have points ignition and has not been changed

Need a voltmeter and see if your getting power on the + side of the coil when key is turned ON. Then check for full 12V on + side of coil when it's cranking

 

[rloucks3]

I had electronic ignition but not knowing electrical I thought if I went to a point system I would be able to fix. That being said the reading I got at the coil with key in on position was 12.45 and 8.95 in start, I used a trigger switch and put negative lead to negative post on battery.

 

[rloucks3]

I had electronic ignition but not knowing electrical I thought if I went to a point system I would be able to fix. That being said the reading I got at the coil with key in on position was 12.45 and 8.95 in start, I used a trigger switch and put negative lead to negative post on battery. I also noticed smoke from distributor when I let off the trigger.

 

[alldodge]

I got at the coil with key in on position was 12.45 and 8.95 in start,

The voltage readings are backwards. Should see full 12V when cranking which bypasses the resistance wire (or ballast resistor). Turned ON it should be around 9V because it should go thru the resistance wire.

Putting a ground wire on the - side of coil will keep the coil from ever firing because coil will not charge up (so to speak). The points open and the coil is charged, the when they close this causes the coil to fire.

The points must open and close as the rotor turns.
Loosen dizzy and rotate it back and forth to see if it does this. At this time also check gap should be 0.022 and dwell angle of 31* to 34* degrees when running

 

[rloucks3]

So the points do open and close, however I burned up the points I think that's what the smoke was from the plastic. On the coil I have ignition wire going to negative post on coil, the condenser going to negative post and r on starter solenoid on negative post. On positive post have brown and tan wire. Is that wiring correct or wrong?

 

[alldodge]

Not correct
Points go to negative side of coil
The "condenser" should be inside the distributor and connected to the points

Should be 2 wires on positive side of coil
White (but might be Brown) and a Tan. White goes to key and Tan should go to starter solenoid

Remove both wires and turn key ON. One will have power and the other should not. With wires still disconnected, crank motor and other wire should have power

 

[Scott Danforth]

use a dwell meter to set points. if there is an issue, you will see it immediately in the meter.

 

[rloucks3]

So I have a wire from the R post that reads 12.35 key on and start I have 10.65.
All brown are no reading with key on.
In start position the brown are still no reading.
There's also a brown and tan wire connected. If it helps at all I did take some pics. One double brown, one brown and tan and a single brown. Seems like starter is not putting out what it should??

 

[alldodge]

The R post ? is that on the solenoid or key?
If at the key then might partly a problem with the key switch. Should get power to I terminal when ON and S terminal when cranking.

Looks like the Brown and Tan are tied together. With no voltage on either one will need to trace the wires. Check

 

[alldodge]

Being a 73 does it have a ampmeter or voltmeter on the dash?

 

[rloucks3]

1st I so appreciate the help so much. No the R post to coil, did have electronic ignition and I thought that was the issue. Yes all brown wires are not producing, I did put a double solenoid for the trim motor. There's also a battery isolator if that makes a difference??

 

[rloucks3]

Being a 73 does it have a ampmeter or voltmeter on the dash?

Ampress

 

[alldodge]

No the R post to coil,

I think we might have a terminology issue. For me the coil does not have R post, it has + and - and a center high voltage. Which one is the R post?

 

[alldodge]

Wiring with transistor regulator

 

[Scott Danforth]

@alldodge R post is the "Relay"post. it provides 12 volts to the coil while cranking. some starters refer to it as an I post for "Ignition"

@rloucks3 if your voltage is less, you either have corrosion on the terminals, or your points are not set right.

start by making sure every connection is clean enough your mother-in-law will eat off them.

Then file the points. rough-gap the points to about .016. use the dwell meter to set dwell to 32 degrees while cranking. install cap, and set timing.

 

[alldodge]

Thanks Scott

Leave all wires of the dizzy except R wire going to + side and black wire going to - side and try to start. If it still does not start, disconnect condenser inside dizzy and try again

 

[Scott Danforth]

dwell meter will read 0 while cranking if the points are not gaped or the condenser is bad.

simple DVM set on capacitor testing will also test the condenser.

 

[rloucks3]

The tan wire is connected to the white wire that is cut off under the dash, the brown wire is not connected to anything. I took a pic , the brown was wrapped in tape.

 

[rloucks3]

@alldodge R post is the "Relay"post. it provides 12 volts to the coil while cranking. some starters refer to it as an I post for "Ignition"

@rloucks3 if your voltage is less, you either have corrosion on the terminals, or your points are not set right.

start by making sure every connection is clean enough your mother-in-law will eat off them.

Then file the points. rough-gap the points to about .016. use the dwell meter to set dwell to 32 degrees while cranking. install cap, and set