Re: Bad ignition coil? Update: Bad owner!

[NW Redneck]

Re: Bad ignition coil? Update: Bad owner!

I'm troubleshooting a no spark problem. I have 9+vdc to the coil + terminal, but no spark. Testing for continuity between + & - is <2 ohms. Between + or - and center terminal I get 7.11K ohms. It's not technically 'open' but it's pretty darned high! What is a normal ohms reading between +/- and tower?

 

[mikeneal]

Re: Bad ignition coil?

Re: Bad ignition coil?

What are you working on?

 

[NW Redneck]

Re: Bad ignition coil?

Re: Bad ignition coil?

Sorry, it's a 1975 OMC 175 (302 ford). Coil is external balast resistor type.

 

[NW Redneck]

Re: Bad ignition coil?

Re: Bad ignition coil?

Anyone know what a good coil should read between + or - and the tower?

 

[Lyle29464]

Re: Bad ignition coil?

Re: Bad ignition coil?

If you tap your engine over the points should open then you should read 12+ at the coil. If it stays at 9 your points are closed clean and reset. If thats it replace them.

 

[bruceb58]

Re: Bad ignition coil?

Re: Bad ignition coil?

Disconnect the negative wire from the coil and connect a jumper wire that you can put to ground. Take the high tension wire that goes from the coil to the distributor and hold it near ground. Now ground the coil with your jumper wire and pull it away from ground. You should get a nice healthy spark. If that doesn't spark, its your coil. If it does spark, then you need to identify what is going on with your point/condensor..

Another easy way to determine if its your points is to put a dwell meter on there and turn the engine over. If you have a problem with the points getting grounded out, you will not get a dwell reading.

 

[TiredoleBoy]

Re: Bad ignition coil?

Re: Bad ignition coil?

Put new points and condensor in the thing and then see what happens.

 

[Bt Doctur]

Re: Bad ignition coil?

Re: Bad ignition coil?

works like this

 

[NW Redneck]

Re: Bad ignition coil? Update: Bad owner!

Re: Bad ignition coil? Update: Bad owner!

Update: Thanks to all those who replied. It turned out not to be the coil, but a case of S.O.S. (Stupid owner syndrome :redface: )
The boat was running rough last trip out (first trip this season) so I was double checking the plugs/wires, points (new near the end of last year, have maybe 10 hours on them and still look like new) and while I was mucking about I must have bumped one of the wires on the ballast resistor as it was just barely on. I tightened up the connection and viola, we have spark! Re checked gap (.017-.018), timing right @ 10*. Advance weights look good and move freely.

I then turned my attention to the fuel system and I found a small amount of water in the bottom of the filter canister (filter new this year) so pulled the float bowl off the carb and found a little bit of gunk in the bottom of the bowl and the fuel inlet screen was plugged up. I pulled the whole carb off and took it apart and soaked everything in carb cleaner and blew it all out with the compressor. Back together and on the boat and it's running better now, but still seems to 'surge' a little bit from 600 to about 675 rpm @ idle. Adjusting the idle screws didn't seem to help. (Holly 2bbl carb BTW, complete rebuild about 4 yrs ago). Any other things I may have missed?