1979 228 Merc correct voltage at coil?

Hi Guys-

Thanks for all the help this forum has given me...what a resource!

My son just purchased a 1979 VIP with a 228 Mercruiser. It is pretty much a junk boat, but we are trying, one step at a time, to get it going.

There was no spark, I tested the coil resistance, and it was bad. Still no spark with the new coil. Voltage at + side of coil was 4.85. Voltage at battery was 12.8. I took a chance and jumpered from the battery to the coil to get 12v at the coil. The motor started right up.

I understand that these coils should not see continuous 12v....Correct?

I have read that there is a resistor wire on this system, should I see more than about 5v if things are working right? If so, what is the easiest (and cheapest!) way to correct the low voltage problem>

Thanks in advance!

Bob

Re: 1979 228 Merc correct voltage at coil?

i just recently fixed the same problem on my boat with help from a member of this forum. you do want a continuous 12v to the + side of the coil. count how many wires you have connected to each side. there should be two wires going to + side and 2 wires going to - side. one of them on the - side is a black wire going to the distributor. the other is a grey wire going to your tach and shift interrupt switch. pull both of them off the - side and test for voltage on + side with a good ground on the engine, not the - side. you should have 12v. my problem was with a random wire that was grounded to the valve cover and then to the - side. that side doesn't get grounded out. if you do get 12v without any wires on the - side, try connecting just the black wire back to the coil and starting the boat. it should start. if it doesn't then you need to check your points inside the distributor. the sticky note labeled adults only has a very good and detailed way to check your distributor if it doesn't fire with just that black wire hooked up.

Re: 1979 228 Merc correct voltage at coil?

Thanks, DixieSpeed-

I am not sure why, but it starts and runs fine now without the jumper. I am looking for loose connections now.

Bob

Re: 1979 228 Merc correct voltage at coil?

The ignition wire is a resistor wire and only delivers full 12v when starting. The solenoid on the starter makes the difference. Points.

When I had this problem I would jump off the positive stern light wire to the coil momentarily to get started then all was fine. I replaced the starter and it's solenoid and all fixed.