3.0 OMC Cobra starting problems

[buckyop]

This will be long but hopefully detailed. I have a 1986 3.0 OMC Cobra motor. I started my boat at home. Ran until temperature gauge reached normal temperature (160). Towed to the lake, 30 minutes. Put boat in, started right up, drove about 10 minutes, cut boat off, swam about 10 minutes. As I tried to start the boat, it took longer than normal, but started. Drove about 10 minutes, stopped, even harder to start. Eventually boat would not start. Towed in. Towed boat home 30 minutes. Tried to start boat again in driveway. Boat started right up. Replaced points, distributor cap, condensor. Started boat at my house. Ran for about five minutes. Ran fine, idled fine, the same as before. Towed to the lake 30 minutes. Put boat in water, drove about ten minutes, stopped, swam about 10 minutes. Hard to start when leaving. Drove about five minutes, stopped, swam about 20 minutes. Boat would not start. Towed in. Towed boat home about 30 minutes. Tried to start boat in driveway. Boat started right up. Boat doesn't do me any good running in the driveway. Do I need to get a camper? Please help!

 

[Boatin Bob]

Re: 3.0 OMC Cobra starting problems

I guess you need to try and determine if it's electrical or fuel related, when it won't start can you move the throttle and see gas squirting down the carb? Is your fuel filter new? Another problem that happens is the fuel tank vent line gets clogged and it becomes very hard for the fuel pump to suck fuel because it creates a vacumm, a quick test for this is to open the fuel fill and if you hear a hissing sound then you know you have a vacumm in the tank, could be by the time you get it home the vacumm has gone and the pump can suck fuel again? When it won't start can you take out a spark plug and hold it near the block (with wire attached) to see if you are getting a spark?

 

[buckyop]

Re: 3.0 OMC Cobra starting problems

Originally posted by Boatin Bob:<br /> I guess you need to try and determine if it's electrical or fuel related, when it won't start can you move the throttle and see gas squirting down the carb? Is your fuel filter new? Another problem that happens is the fuel tank vent line gets clogged and it becomes very hard for the fuel pump to suck fuel because it creates a vacumm, a quick test for this is to open the fuel fill and if you hear a hissing sound then you know you have a vacumm in the tank, could be by the time you get it home the vacumm has gone and the pump can suck fuel again? When it won't start can you take out a spark plug and hold it near the block (with wire attached) to see if you are getting a spark?

 

[buckyop]

Re: 3.0 OMC Cobra starting problems

Originally posted by buckyop:Bob, Thanks for the reply. While on the water and still in an angry, frustrated state, I added starter fluid. This did not work. I later checked for fuel going into the carb. I did have fuel. I did remove a spark plug wire, put in a screw driver, and tried to get a spark while cranking. I did not have a spark. I failed to put the coil wire close to the block to check for spark coming from the coil. Could my ignition coil be breaking down or leaking as the motor warms? Also, someone stated that they had some experience with the compression being low in an old chevy truck. The boat runs very strong and very smooth at all speeds. I have pulled skiiers, tubers, and have had no trouble up until recently.

 

[Boatin Bob]

Re: 3.0 OMC Cobra starting problems

Sounds like it's leaning towards an electrical problem then. Next time it won't start you need a meter or at least a 12v test light to go across the coil and see if you get 12v while turning the key to start. If you do then when you let go of the key you should still get 8-9v at the coil through the resistor wire. If no power at coil, check the big black connector on the main wiring harnessat the engine, these can come loose or be corroded inside. Another way out thought might be your ESA module, I have heard of these things doing funny things if they get too hot, possibly it's dragging the voltage down, you can bypass the ESA as a test by unplugging the connector that has the purple and grey wires in it. (note, this will make it hard to shift from F or R into neutral but it's just a test). I think this is going to be a process of elimnination. I'm assuming new points are set to correct gap/dwell and timing is OK.

 

[mrm]

Re: 3.0 OMC Cobra starting problems

Try rebuilding the starter. A cold starter turns over better than a hot starter. Its what fixed my starting problems on my 3.0 when it would start cold, but not after running for awhile. Also clean or replace battery cable wires. And make sure you have a good battery.<br /> MRM

 

[rattana]

Re: 3.0 OMC Cobra starting problems

It could be your coil breaking down. Test the voltage to the coil like Bob says. If you do have voltage, I would try another coil.

 

[Boatin Bob]

Re: 3.0 OMC Cobra starting problems

Just reading your initial post again, when you say it gets harder to start I assumed you meant it still turned over fine but it wouldn't fire up or do you mean it wouldn't turn over anymore?

 

[buckyop]

Re: 3.0 OMC Cobra starting problems

Bob, The motor turns over fine until I eventually run the battery low. Please understand that I have been stranded out on the lake each time with my wife, eight year old son, and this last time with my 10 month old daughter. I have cranked for along time hoping to be able to get them home safely. If it turns out that it is my coil, is it just a bad part or is there something causing it to go bad?

 

[rattana]

Re: 3.0 OMC Cobra starting problems

If the voltage to the coil is too high when the key is in the run position it can cause problems for your coil.

 

[Boatin Bob]

Re: 3.0 OMC Cobra starting problems

buckyop....all the folks on this board here are trying to help you based on the symptoms you are giving us. But we are just giving you our best educated guesses until you can start to provide some more info, such as measuring the voltage at the coil, as I said before the coil should get a full 12+ volts while starting and then drop down to 8 or 9 volts because the power then goes through a resistor wire. If you feel it's the coil then go out and buy one and try it, worst case is you will end up with a spare. You need to see if you do get any spark out of the coil, maybe the points are marginally adjusted, could your distributor or shaft be worn so you have a wobble in it? I understand you want to get this fixed as no one wants to go out in a boat they feel will break down.

 

[Bondo]

Re: 3.0 OMC Cobra starting problems

Yep,<br />YOU,+ Only YOU can do the Actual Diagnosis.......<br />Get a Multi-meter,+ Test Light.....<br />You've got to track down Where,+ Where Not, you have Power, WHEN the problem is Happening.......<br /><br />Throwing Parts at it, <br />Till you get it Right, <br />Isn't the way to do it..........