OMC Cobra 2.3 liter

[timtress]

I have a 1987 Renken 1750 with a 1987 OMC Cobra 2.3 liter. Model# 232AMFTC.

I bought this boat a little while ago and apparently, because of my ignorance, was taken on this purchase.

I have done a number of things to this boat an engine already. Which I now realize was a very dumb mistake, as I did all these things before making sure the motor was good. I just figured out that three of my cylinders have only 90psi of compression and the last one has only 30psi. I followed the instructions in the manual and squirted a little oil in the cylinder and rechecked the compression resulting in readings of 150-165psi in each cylinder. Making me believe the piston rings are shot. My conclusion was seconded by the all the gas in my oil after trying to crank it over a few times. The engine is firing, but will not start. I believe I'm having a problem with the resistor wire on top of my bad piston rings.

I need advice on whether to replace or rebuild the engine? Or what my options are for replacing the motor with or without changing the outdrive. I could really use some help. I didn't pay too much for the boat, but I have invested a lot in to it now. I reupholstered the interior as well as replaced many parts on the trailer. The boat is in good condition now, but I am at a loss for what to do with the engine and outdrive???

Please tell me what my options are... I wanted to upgrade my horsepower and figure if I'm going to now would be the time.

Thanks so much!!!

 

[Gary H NC]

Re: OMC Cobra 2.3 liter

At this point i would pull the head off and take a look...costs nothing.

 

[danond]

Re: OMC Cobra 2.3 liter

If it hasn't been started in quite a while, your compression numbers might be wrong. I'd suggest getting it running first.

When I got mine it had compression numbers like yours. Once I got it oiled up and running, things sealed up again. Valves don't like to sit in one place forever then be slowly opened and closed, rings don't like to sit forever, either. Mine came back and it has 140+ or so compression all around now without an additional oil squirt.

Gas in the oil is normal after lots of cranking. You flooded the heck out of it, and the previous owner did, too. Change the oil. I also got mine with oil that'd been filled with fuel. It took 4 oil changes to get it all out.

How old is the gas? Even if you get a new engine, you will still need working ignition and fuel delivery systems. Fix those while this engine is there.

 

[timtress]

Re: OMC Cobra 2.3 liter

I appreciate the help. I've been trying to take your advice and get it running to see what's going on with it, however I think I'm having an issue with the resistor wire and I can't seem to figure it out. I have no power to accessories when I have the key in the on position. Plus the engine fires up really strong when turned to start but dies immediately when I let the key go and it goes back to the ON position... My service manual says not to shorten or replace the resistor wire, but to replace the whole wiring harness? Is this really necessary? And if so where would I get a wiring harness???

Thanks

 

[danond]

Re: OMC Cobra 2.3 liter

If it fires up strong, don't go after the compression thing until everything else is working.

If you're losing power when you turn it to ON, you need to check the starter wiring and the engine harness plug.

Do you have a wiring diagram? If you don't, you can download one from the ADULTS ONLY sticky of the forum. Start following your issue from the battery and trace each wire. I bet you'll find a bad/corroded connection.

 

[bruceb58]

Re: OMC Cobra 2.3 liter

If you have power to turn the engine over, that you means you have power to the ignition switch. Start looking at the other post of the ignition switch that should have power on it when the swich is in the run position.

 

[timtress]

Re: OMC Cobra 2.3 liter

Correct. I do have power to the ignition switch in the "START" position. Not in the "ON" position. The instrument gauges light up when cranking the engine, but cut out in the "ON" position same as the engine does. I have heard this could be a problem with the resitor wire? I think the resistor wire is bad, but my book says to replace the whole harness. WHere do I find a new harness? And is there a way to just replace that wire???

 

[bruceb58]

Re: OMC Cobra 2.3 liter

Because you say the gauges are on while cranking, the resistor wire is ok. This is why. When cranking, one of the posts of the starter solenoid feeds 12V directly to the coil, normally bypassing the resistor wire. In your case, you must have a break after your ignition switch. When you crank the engine, you get 12V at the coil and then backfeeds down your resistor wire back to the dash and turns on your gauges. You must have an open between your ignition switch and the gauges. Check the voltage at your ignition switch in the run position.

 

[proshadetree]

Re: OMC Cobra 2.3 liter

Had this problem with mine It was the safty plug on the dash.I forget at the monent what it was called.You know when you get up it kills moter.Check for 12 volt at coil.You could also hot wire it and run for a short time.

 

[timtress]

Re: OMC Cobra 2.3 liter

Haven't got a chance to check for power at the ignition switch yet, but if it was the safety plug/kill switch thing wouldn't it not even turn the engine in the "start" position?

If I don't have power at the ignition switch at the "on" terminal what would cause that?

If I do, what would be the next point to check???

 

[timtress]

Re: OMC Cobra 2.3 liter

Also how do I hot wire it? WOuldn't that resistor wire prevent me from jumping directly to the coil? I thought that had to be in line when the motor was started...

 

[proshadetree]

Re: OMC Cobra 2.3 liter

Mine would crank and start then die as soon as the switch was in run .Wire to the hot side of resistor.Either way if its not run long you wont fry it.Check safty plug first.If ticked me off when I found that after a 1/2 day looking

 

[timtress]

Re: OMC Cobra 2.3 liter

At work right now. I'll check it as soon as I get home, but if my memory serves me correctly I don't have a safety shut off thing. We'll see. Thanks Everyone for the quick responses and good info!!

 

[timtress]

Re: OMC Cobra 2.3 liter

I did not see a kill switch safety thing, however I did run a jumper wire from the "ON" position terminal to the positive terminal on the ignition coil and cranked it up. It did start and rev up and remained running in the "ON" position. So, one problem solved. Although shortly after it cut out. I'm thinking it may be a fuel problem.

I have a small electronic fuel pump temporarily installed, because I don't think my mechanical pump was working properly. The electronic pump is the right pressure 4-7 psi. I'm have a inline fuel filter and can see the fuel pumping through. So I'm not sure what is happening or why it might be cutting out after a short while. I do think that the ignition switch problem is fixed even though it is temporary.

So, any new suggestions for me???

 

[timtress]

Re: OMC Cobra 2.3 liter

Just had a thought... Was wondering if the problem may now be because of the gas filled oil??? Maybe I should try to change that tomorrow? I don't know. Any ideas shoot em my way. I'm ready to try pretty much anything. Especially since the awesome people on here have already helped me run down one problem with my money pit.

 

[danond]

Re: OMC Cobra 2.3 liter

Dude. You're trying to start the engine with crappy, fuel-filled oil? tsk tsk.

Get a whole bunch of cheap Wal-Mart 30wt. Change the oil.

That's not why the engine isn't starting and running, by the way. Still working on that one, but now is a good time to start doing things one at a time instead of jumping all over the place.

Change the oil, clean up all your start and ignition circuit wiring connections and check everything with a meter (if you don't have one, get one - cheaper than a mechanic!), try to start it.

 

[proshadetree]

Re: OMC Cobra 2.3 liter

Use a meter or at very least a test light.And change that oil.Let us know what you find.

 

[timtress]

Re: OMC Cobra 2.3 liter

Ok, so yesterday I rewired most of the ignition panel. Put brand new fuse board. Checked all the connections with voltmeter and everything came back right... Resistor wire checked out fine.

Engine will now turn over and fire, but will only fire with starting fluid... Will not start. I do have power at the coil. I'm think it is a fuel issue, but don't know how to check out the carb. I have fuel coming to the carb, but I don't know if the carb is working properly...

Any ideas?

 

[timtress]

Re: OMC Cobra 2.3 liter

By the way, I have never rebuilt a carb, don't know how hard it is. The guy I bought the boat off of told me it was rebuilt last year, but I'm not sure how reliable that is.

 

[bruceb58]

Re: OMC Cobra 2.3 liter

Throw away your starting fluid unless you want to kill your engine. Ether is very volatile and it can ignite and totally wrong times. You should pour a little gas down the carb for troubleshooting purposes.

Also, if you are using an elecric fuel pump, you need to wire it through an oil pressure switch so it does not run with the key on and the engine not running.