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1974 302 Mercruiser engine wiring problems

C

Chess

New member
I am installing a 1974 302 Mercruiser engine. It is in the boat and I have hooked up the harness, wires to the starter...coil..etc. I have 2 tan wires hooked up on the "IN" side of the coil and 1 black wire hooked up on the "out" side of the coil. I am getting a reading of 8 volts going in and 8 volts coming out and I think it should be 12V in and out. What am I doing wrong? OTHER PROBLEM..When I turn the key to the "on" position, the engine tries to "start", which is not right. But when I immediately turn it "OFF" and then try it again...It does nothing! My after market book does not tell me anything about a safety switch. Is the circuit breaker stopping it from turning over again? And what have I got wired wrong for it to be doing all of this? I thought that I had wired it according to the manual, but apparently not. BIG THANK-YOU for any HELP that anyone can give. Needless to say we have changed the wires around, but apparently have not gotten the correct combination.
 
Starter small nut wires on right ?

Something tells me someone shunted in different color wires, but one wire thats hot is the purple.

Disconnect the battery check and or change the wires on the starter, you touch the wires on the slav ?

What you can do to narrow it down is to run a jumper straight to the coil pos from the pos, side of the coil and jump the starter with water goin to the drive.

It start ? if yes you will need to turn the switch off and remove the wire from the battery.

Do not leave the jumper wire on cause it will melt and fuse the points, if closed.

It's a test understand not to to be left on.

Talking about the points they set up correct, wires to the plugs correct, double check.

Battery fully charged ?

Ground good on the block ?

You are in neutral correct ?

Post back !
 
One of the brown wires runs to the tachometer and the other is connected to an in-line resistor wire that drops the voltage so that the points don't fry.
 
On the marine starter, it only has the one main power connection! The 2 small nuts that I think you are talking about are located separately on the solenoid. The Battery main power connection on oneside and the starter power on the other side with the 2 small nuts in between the 2 main power sources that I just mentioned first. I will use all the information that you sent and continue from there. THANKS for your help.
 
I have a mid 70's 302 marine engine that I had to replace an engine wire loom, after searching the whole world for it i finally found one, the only thing is i had to extend some of the wires, wires to the coil were 2 whites and a purple, from what i could tell I connected the 2 whites to the positive side and the purple and black distributor wire to negative, i have 4.9 volts at the positive side of the coil, is this correct ? also when trying to start it the wire loom heats up from the coil back towards the solenoid, the engine fired a couple of times but due to a bad fuel pump im having to change it, my question is... what may be wrong here, I have replaced the points and condenser, the 2 white wires... how can i tell if one of them is a resistor wire, I don't see a resistor anywhere in line from the switch, Help! I'm trying to be safe here. Thanks for any Reply.
 
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This 5 minute edit/delete sucks!! Needs to be changed to 20 minutes!! Some things take time to edit!!
 
The purple wire drives the warning light on the quicksilver instrument panels, if used, in that era....

the other thing to watch is amp meter leads....the harness may/may not accommodate those connections...

If the slave solenoid has been replaced, it may not have the R terminal to feed current to the ignition coil while cranking...

Have ~ 5VDC on the coil likely won't be enough to start the engine...something isn't connected correctly or there are old components that have corroded...you can measure the voltage drop thru any wire to see if it is a resistor wire or not...
 
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