Problem with coil?

[Mrcleaningguys]

I don't have any spark. With key on, the white wire one the positive side of coil is only getting 4v, but same white wire is getting 12v at ignition switch. Negative side of coil is getting 12v. Replaced coil, same results. Bad ground somewhere?

 

[biggjimm]

What are you working on exactly?
Is it a point distributor? If so it It's only supposed to see I think 4v-9v on the coil + with the key in the run position. It should show 12v when the starter is engaged (to provide enough spark to make up for the voltage draw from the starter running, it comes from the little post on the starter solenoid) & then after it starts the voltage drops back down due to the online resistor in the white wire coming from the key switch. You should have 12v on the white wire at the key switch to run your gauges but it should show lower at the coil + terminal like you say. I just had the same problem with my 140, the starter wasn't sending voltage from the little post on the solenoid & it wouldn't start. I jumpered 12v from the battery to the coil + & then it would start & remove the jumper & it would then stay running from the resistor wire voltage. My problem ended up being the ground cable from battery to the block was cruddy. Go to the adults only sticky at the top of the page & there is a thread about troubleshooting points ignition ad well as explaining how it works. Good luck with it. Mine drove me nuts for a couple days but I finally got it. Jim.

 

[Mrcleaningguys]

What are you working on exactly?
Is it a point distributor? If so it It's only supposed to see I think 4v-9v on the coil + with the key in the run position. It should show 12v when the starter is engaged (to provide enough spark to make up for the voltage draw from the starter running, it comes from the little post on the starter solenoid) & then after it starts the voltage drops back down due to the online resistor in the white wire coming from the key switch. You should have 12v on the white wire at the key switch to run your gauges but it should show lower at the coil + terminal like you say. I just had the same problem with my 140, the starter wasn't sending voltage from the little post on the solenoid & it wouldn't start. I jumpered 12v from the battery to the coil + & then it would start & remove the jumper & it would then stay running from the resistor wire voltage. My problem ended up being the ground cable from battery to the block was cruddy. Go to the adults only sticky at the top of the page & there is a thread about troubleshooting points ignition ad well as explaining how it works. Good luck with it. Mine drove me nuts for a couple days but I finally got it. Jim.[/QUOTE

Sorry. Should've been more specific. Its a mercruiser 165. Has an inline 6 engine. Points ignition. Got everything rewired, (I hope correctly), and finally decided to fire it up. And you know the rest....

Another issue I'm having is, I wired the fuel pump to the a toggle switch on the dash. I ran THAT switch through the ignition switch, (double fool proof.) It acts like it isnt getting power. Just kind of sputters. If I touch it to the battery it comes alive, but not through the switch. Too many switches? Too much wire? I used a heavy gauge wire for the fuel pump. Same thing is happening with my blower. Battery=power, switch=nothing. Not sure what the issue is here. Thanks biggjimm

 

[Eric 3.7LX Alpha 1]

You know you can actually test a coil using a digital multi meter to see if it's good or bad by checking resistance between the primary and secondary coil... It's pretty easy actually.

Oh well, now you have spare. Your coil will get full battery power when cranking the engine over then switch back to that 4-volts when the key is in the "run" position.

You probably need new points.

Click on this link:

How To: Troubleshoot a Points Ignition System

http://forums.iboats.com/forum/engi...roubleshoot-a-points-ignition-system?t=335407

 

[biggjimm]

Is the fuel pump wired up through an oil pressure switch? It should be for safeties sake. I'd wire those other circuits up through a relay or something to get some of that amp draw off of your ignition switch. I know on mine that wire isn't very heavy & I'd be afraid of running to many things directly off the key switch.
Did you read through the link Eric give you on troubleshooting the ignition?

 

[Mrcleaningguys]

Is the fuel pump wired up through an oil pressure switch? It should be for safeties sake. I'd wire those other circuits up through a relay or something to get some of that amp draw off of your ignition switch.
Did you read through the link Eric give you on troubleshooting the ignition?

Fuel pump is not wired through oil pressure switch. When I got the boat, the fuel pump had 9 or 10 different color and different size wires spliced together leading to a small toggle switch. It worked when I hooked a battery up and flipped the switch, so all I wanted to do was eliminate all the splices and add a failsafe. Ignition seemed good for this. I'll try to figure out this oil pressure switch deal. Update: fuel pump only sputters even when touched to positive battery terminal.
Fuel pump was the only thing ran through the Ignition switch other than gauges. Accessories are ran from battery to fuse block.

I read through the link Eric posted. Looks extremely helpful and I'm heading out to try them now.

Thanks Eric and thanks biggjimm.

One more question.... Would a bad tach possibly be the cause of my issue?