Weak spark on OMC 2.3L sterndrive

[ypzilon]

My 2.3L OMC won?t start so I began to check the spark. It was VERY weak.
I have checked the pointer cap, the dwell is 37 degrees (should be 36+/-2) and the pointers don?t looks worn to out.

The spark jumps about 1/6" (the manual says at least ??) and is very thin, and it doesn't matter if I check at the plug end of every spark wire or at the "main" spark wire. That should exclude the cap and rotor.
Should I change the coil or pointer/condenser?

 

[Boatin Bob]

Re: Weak spark on OMC 2.3L sterndrive

Check the voltage on the + terminal of the coil first, maybe something is dragging it down too low? Should have 12v there during start and then around 9v when running.

 

[ypzilon]

Re: Weak spark on OMC 2.3L sterndrive

Now I have checked some more. At the +terminal on the coil I have 6.5-7V while cranking and at the +terminal at the battery I have ~10V while cranking and ~11.9V with the ignition on but engine of.

The primary circuit resistance on the coil is 2.08 ohms and 10800 ohms at the secondary circuit. My Clymer manual says that I should have 1.43-1.58 ohms and 7500-8700 ohms. Should I replace the coil and put a new cable to the +terminal?

 

[Boatin Bob]

Re: Weak spark on OMC 2.3L sterndrive

As a test you could try a jumper wire directly from the + battery post to the + coil post and see if you get a good spark while cranking.

 

[ypzilon]

Re: Weak spark on OMC 2.3L sterndrive

I can't find any good wiring diagram in the manual but I think that the +terminal is feed from the solenoid while cranking and from the alternator while running. Is that correct?
If so, maybe I should check that the cable between the solenoid and the coil isn't broken then?

 

[Don S]

Re: Weak spark on OMC 2.3L sterndrive

How long since the points were replaced. They do glaze over. That's why in the summerizing post that is a stick at the top of this forum says to replace them yearly.

 

[Coors]

Re: Weak spark on OMC 2.3L sterndrive

Now I have checked some more. At the +terminal on the coil I have 6.5-7V while cranking and at the +terminal at the battery I have ~10V while cranking and ~11.9V with the ignition on but engine of.

The primary circuit resistance on the coil is 2.08 ohms and 10800 ohms at the secondary circuit. My Clymer manual says that I should have 1.43-1.58 ohms and 7500-8700 ohms. Should I replace the coil and put a new cable to the +terminal?

Also, should have about 12.5 at the battery.

 

[Boatist]

Re: Weak spark on OMC 2.3L sterndrive

First is you battery fully charged up. 12.5 to 12.6 volts.
When cranking the coil + voltage should be the same as the battery voltage. Usually about 10 volts while cranking.

First thing I would do is just take a jumper wire from the battery plus teminal to the coil + terminal and try to start it. I think it will start. Need to make sure this wire does not touch anything to short out to.

I have a 1980 3.0L OMC and it has a wire from the starter solenoid to the plus side of the coil. So any time the started solenoid is pulled the coil has full battery voltage or about 10 volts. Once it starts and the solenoid drops back when you let go of the key. At that point the battery and alternator voltage come up to about 13.8 volts. The coil is supplied about 9 volts thru restance wire.

On My 1980 boat I have only changed the points and condensor one time and even then they had no problem but i just felt like 15 years was time to change them. I carry that old set and a new set in my tool box just in case.

If you do change them make sure to do it right or you will have bigger problems.

It sounds to me like the wire from the starter solenoid to the coil is broken, disconnected or not making good contact as that would explain the voltage being 4 volts too low and a weak spark.

If you charge your battery with a charger right before starting it may not drop all the way down to 10 volts either.

The rotor borken, distributor cap worn or bad wires can also cause weak spark. One thing I have done on my boat is the high tention wire from the coil to the distruibtor cap is a solid wire not carbon. I have alway done this as have seen many carbon wires go bad and if this wire fails you will be dead in the water. On my boat have not gotten any noise in the radio or depth finder and GPS units at a result.

Good luck and tell us what you find.

 

[ypzilon]

Re: Weak spark on OMC 2.3L sterndrive

Now I have charged the battery (it was almost fully loaded before) and I also found that the cable between the solenoid and the coil was broken.

The spark is now great at the end of the high tension wire from the coil to the distributor cap, but at the end of the other cable is still weak, but those wires are low-cost and have around 8000 ohms and will be changed at Monday together with condenser, breaker points and rotor.

 

[saddleman]

Re: Weak spark on OMC 2.3L sterndrive

My 2.3L OMC won?t start so I began to check the spark. It was VERY weak.
I have checked the pointer cap, the dwell is 37 degrees (should be 36+/-2) and the pointers don?t looks worn to out.

The spark jumps about 1/6" (the manual says at least ??) and is very thin, and it doesn't matter if I check at the plug end of every spark wire or at the "main" spark wire. That should exclude the cap and rotor.
Should I change the coil or pointer/condenser?

Check the resistance with a decent ohm meter between the negative screw terminal and the high tension or coil wire socket it should be 7500-8500 ohms
if not go buy a new marine coil for $52.00 it is vary different than a typical $12.00 coil from the auto parts store. I just had the same issue.
good luck
keith

 

[bruceb58]

Re: Weak spark on OMC 2.3L sterndrive

Another old thread. You need to check the dates of these posts you are replying to. Doesn't help an original poster who is probably not going to be looking anymore.