I got a good one for ya...

1989 OMC Cobra 4.3

Cruising along at about 2900 rpm, just enough to stay planed out in 12 foot deep water with the kids and wife in the bow, stereo on but not too loud (runs on a separate battery hooked up to an isolator anyway). No lights on, blower running, engine temp was 160 or so, smooth water.

Engine has been through a complete service - oil, plugs, wires, cap, rotor, pertronix, flamethrower coil. Carb has been rebuilt, engine has good compression (140+), oil pressure is about 50psi at 2900 rpm, drive has been serviced (gimbal, u-joints, bellows, transom seal, new lube, doesn't leak, no noises). Has a new transom shift cable that has been adjusted to factory spec, shifts like a dream. ESA works very well. The engine harness plug has been cleaned and contacts coated with copper-based contact improver goo. I can't remember the name of the product. Alternator charges the batteries, all the gauges work great, starter has never given me issues, not even a hiccup. Battery cables are all new, contacts were cleaned just a few weeks ago (engine and battery ends). Engine oil is very clean, just changed. Cooling system was pressure checked a few weeks ago. Trim pump has had fluid replaced, contacts cleaned and coated with liquid electrical tape.

About 20 minutes into our leisurely trip, it shuts off like I turned the key. No noises like we hit something. I can still hear the blower motor running. Turned the ignition to start, no click. Turned it to start a few more times, nothing. No clicks. What I can't recall is if I had it in gear when I tried to start it again. We were in the river going against current, being followed by a few other boats so I panicked for a second and I think it was still in gear. Do Cobras have a safety that won't allow it to start in gear? I'm going to go find my manual and check.

Regardless, I opened the engine compartment, nothing was weird, so I closed it, went back and hit the key and it started like normal (one revolution) and fell into it's typical nice 800rpm idle. Took it back another 20 minutes to the dock, no issues. Idled at the courtesy dock for a solid 10 minutes, everything excellent. Once home, checked the prop, not nicked or bent (nor was the skag).

Where should I start debugging this one?

Re: I got a good one for ya...

tach shorted out? safety lanyard switch ? ign switch? harness connector under dash?

Re: I got a good one for ya...

Thanks for the ideas.

I'm going to replace the ignition switch. It's cheap, and I have the original one anyway so who knows.

No safety lanyard on this boat. Not sure on the tach. Maybe? I'll be unplugging all the harness connectors to check for crap this weekend. It's a pretty clean boat, though. Stored inside, so I don't plan to find anything in there. Can't hurt though.

Re: I got a good one for ya...

You now have an INTERMITTENT ELECTRICAL PROBLEM.
What fun, and so easy to find .................... NOT...
1st. DO a compression test. won't help, but will keep you busy for a while.

Time to start the engine on muffs or in the water and do the wiggle test of everything. Front to back of the electrical system. I have found corroded wires half way from engine to helm where a screw went through the wiring harness and it only acted up at certain speeds. Never could figure out why.

Re: I got a good one for ya...

I did a compression test right away. Seemed like the right thing to do!

Wiggle test makes sense. I'm going to do that first. Ugh.

Re: I got a good one for ya...

I know you just changed the filter but, you might want to try to dump the gas filter to see if it has a lot of dirt in it. I just had a problem where it would do the same thing as your boat and it was the gas filter cloged. and I just changed the filter a few rides before it happed to me. I changed the filter and no more problems. Just a thought.

Re: I got a good one for ya...

shdw2001h said:

I know you just changed the filter but, you might want to try to dump the gas filter to see if it has a lot of dirt in it. I just had a problem where it would do the same thing as your boat and it was the gas filter cloged. and I just changed the filter a few rides before it happed to me. I changed the filter and no more problems. Just a thought.

Click to expand...

He turned the ignition and did not get a response at all. A bad filter would not cause this issue.
I hate electrical problems. Good luck danond.

Re: I got a good one for ya...

So you leave your blower on all the time too? I do that as well, but not on purpose.

Re: I got a good one for ya...

I'm pretty sure that an OMC Cobra has a neutral safety switch in the control box. In fact, I doubt there's a boat built that doesn't have one?
Next, a complete loss of power, I'd suspect the ignition switch, or something related to it (are all your coil wire connections tight? and in good shape?)

Go figure, what happens if you remove the igniton wire from the coil, the engine dies. This is the same principle as a the old fashioned "kill switch". Or, a problem with the pertronics unit But, that don't seem logical?

I would say a bad battery cable connection, but if your blower was still going, it can't be that, unless it's on a seperate circuit?

Re: I got a good one for ya...

It is very possible he left the unit in gear when trying to restart though, which would cause "nothing" to happen. I would actually just replace the ignition switch as a first step to eliminate the possibility that it simply shut off do to bad contacts. Otherwise, I'd just go like normal until the problem surfaces again. Since the blower was still running, it's not as if a breaker tripped or the battery went dead. The only other likely source electrically would be an overheated coil which cut spark to all cylinders, but would have likely cut out again after running for another 10 minutes while hot. Fuel could be an issue, but normally it would stumble or have running issues; they normally don't stop dead cold while underway with a fuel problem.

Re: I got a good one for ya...

IVAZ said:

He turned the ignition and did not get a response at all. A bad filter would not cause this issue.
I hate electrical problems. Good luck danond.

Click to expand...

I seen it but when in one ear and out the other. when I wrote the message.

Re: I got a good one for ya...

I am still hung up on the neutral switch too. If that explains the no crank, and it would, then I would still consider fuel in play.

Re: I got a good one for ya...

I would tend to agree with Bubba that it is probably not the switch in and of itself. I would guess more along the lines of a connection problem somewhere. I'm not saying this will be your solution, but I just went through some wiring where I believe the draw from my blower was causing an open circuit due to a faulty connection(s) either in the blower cicruit or elsewhere. When I tried to start the blower, I lost all power to everything -- shut the blower down, turned on the motor again like butter as if nothing happened -- until I tried the blower again. Touchy stuff.

Is your blower on it's own circuit? Or were any of your other accessories working before or after? I saw you said you had a stereo on with another battery...did that stay on?

Are you sure you didn't bump the key with your knee or something? I've done it! It would also be nice if we could disambiguate the ignition attempts as to wheter or not the boat was in F.

Re: I got a good one for ya...

Ok so I'll try to answer some of these and I'm also going to get out there tonight and do some debugging.

It's possible I bumped the key... but I wasn't moving around, just lounging in the captain's chair staring at the moron in the cabin cruiser coming at me at about 35mph as he passed by a bunch of guys who were fishing, shoving them all into the shore. Sigh.

I believe the blower has its own breaker, but I can't remember for sure. None of the breakers popped (they are all manual reset), no blown fuses.

I don't think it was fuel - not ruling it out, but that engine doesn't stumble at *all*. Nothing; ever, and I always top off the tank before we leave on any trips. Didn't stumble this time before or after dying. When I first got the boat last year I had the tank pumped, few gallons put in, shook it up, pumped it again, repeated, nothing but fuel came out each time. Plastic tank.

The Cobra wiring diagram in the factory manual doesn't show a safety switch, but that doesn't surprise me that the answer isn't easy! I'm going to see if it has one tonight by seeing if the starter will click while it's in gear. I also saw in the diagram that the ignition power comes from a bolt/nut on the starter assist relay. The previous owner messed with that area installing the battery isolator...maybe there's a loose nut back there.

Bubba I think you're on the right track. I got a new ignition switch today anyway (it has nice rubberized keys so it's cooler than my original one) and I'm going to follow that lead to the engine while I'm in there and see what I find.

Re: I got a good one for ya...

skargo said:

So you leave your blower on all the time too? I do that as well, but not on purpose.

Click to expand...

Only when we're traveling slow. If I'm not on plane, or just barely, I leave it on. Doesn't hurt a thing and I can't hear it anyway. I'd rather forget it and run the battery dead than blow up.

Re: I got a good one for ya...

danond said:

Only when we're traveling slow. If I'm not on plane, or just barely, I leave it on. Doesn't hurt a thing and I can't hear it anyway. I'd rather forget it and run the battery dead than blow up.

Click to expand...

I guess it's a good thing I'm forgetful, I wonder if the blower will shut off if they overheat?

Re: I got a good one for ya...

Dunno, good question though. My blower is original, so it's 20 years old. Wouldn't surprise me if the bearings are bad.

Re: I got a good one for ya...

The blower or anything else for that matter that loads down the electrical system could cause you to stall. It would only do this if you had a poor electrical connection somewhere. Worn bearings in a blowere that even doubled the current draw would not be causing a problem on its own...only in conjuncion with a resistive electrical connection.

Re: I got a good one for ya...

I'm betting it's electrical myself, as I mentioned possibly the ign.switch

Re: I got a good one for ya...

If you have an OMC remote control it definitely has a neutral safety switch....I found this out when I first got this boat and it would not go to neutral...had to shut it off at idle in gear....then had to jiggle the control back to neutral to get it to crank....I'd be looking at the switch...and the wiring that goes from the switch to the ig circuit..and to be on the safe side check the big glass fuses in the harness...they can get corroded even in those rubber fuse holders...finally go back to the ig coil and check both connections there...