omc cobra 302 5.0 HO dies under load AFTER running well for a while

Hi Guys. I have an 89 bayliner with original omc cobra 302 HO motor. I just purchased it, and it was "supposidly ready to go". PO has documentation of carb cleaning, new alternator, and rebuilt starter all within the last year. The boat runs great without load initially, and even runs well off of the trailer and out of the marina, but today i get about a half mile up river and she stalls out and is dead in the water (not to mention in the middle of the channel, scary). it would still idle in short intervals but would not go into gear under load without dying. Now, a gentleman at the marina is convinced this may be due to water in the gas tank. says since the water sits lower than gas, it runs fine until i get it shook up from chops, and then it trys to pull water up to the motor and prevents it from getting sufficient fuel. Is this a posibility? what are some other possibilities? plugs seem to be good, and carb seems to have been serviced rather recently. what should i do from here? i truly appreciate any and all suggestions provided. Please let me know what additional information i can provide to assist in diagnosis. Thank you! Ryan

Re: omc cobra 302 5.0 HO dies under load AFTER running well for a while

Is this a posibility?

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Ayuh,... Very possible...

Check, 'n change the fuel Filters...

Re: omc cobra 302 5.0 HO dies under load AFTER running well for a while

The boat runs great without load initially, and even runs well off of the trailer and out of the marina, but today i get about a half mile up river and she stalls out and is dead in the water (not to mention in the middle of the channel, scary). it would still idle in short intervals but would not go into gear under load without dying.

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Sure sounds like either a partially plugged filter, plugged fuel pick-up(in the tank) or plugged fuel tank vent.........

Re: omc cobra 302 5.0 HO dies under load AFTER running well for a while

ok, so couple of noob questions. Firstly, is there an electronic fuel pump on this? if so, where? also, i kno the pickup line isnt clogged, as i removed it and it flows freely. now, what is the best way to remove that giant fuel filter? will a large oil filter wrench do it? i also know that it isnt water in the tank as i tested that also. Thanks so far guys

Re: omc cobra 302 5.0 HO dies under load AFTER running well for a while

SRGaudio said:

ok, so couple of noob questions. Firstly, is there an electronic fuel pump on this? if so, where? also, i kno the pickup line isnt clogged, as i removed it and it flows freely. now, what is the best way to remove that giant fuel filter? will a large oil filter wrench do it? i also know that it isnt water in the tank as i tested that also. Thanks so far guys

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There should be an engine driven pump if it's really a 1989 model.

The fuel pump and filter should look something like the following from http://epc.brp.com


A filter "wrench" is what you should use to remove filter.

Re: omc cobra 302 5.0 HO dies under load AFTER running well for a while

ok so, update. I have replaced fuel filter, verified vent tube isnt plugged, and replace vaccum? line from carb to fuel pump(previous one was pinched) took her out today, same issue. ran great for 20 minutes or so. only difference is now i think i smell gas... so, before i delve into the fuel pump, do you think i should check the plugs or coil first?

Re: omc cobra 302 5.0 HO dies under load AFTER running well for a while

SRGaudio said:

ok so, update. I have replaced fuel filter, verified vent tube isnt plugged, and replace vaccum? line from carb to fuel pump(previous one was pinched) took her out today, same issue. ran great for 20 minutes or so. only difference is now i think i smell gas... so, before i delve into the fuel pump, do you think i should check the plugs or coil first?

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You could check the plugs I suppose.....if it hasn't had new plugs, points, condenser, dist cap etc in a long time you should do it anyway.

If you smell gas, you might have a bad pump dumping a small amount of gas into the the oil.

Another thing you can do is run the boat from a completely separate fuel source (small outboard tank. Try disconnecting the fuel line from the carb and determine if you have adequate fuel flow to it.....let it run into a small container.

Do this outside (away from the house) and have a fire extinguisher ready...

Re: omc cobra 302 5.0 HO dies under load AFTER running well for a while

this problem sounds firmialier, is it possible that you are over heating which would mean a water pick up problem, maybe impeller, you may want to use a little more accurate temp check to make sure, my eng runs about 140 degrees, just to give you an idea.

Re: omc cobra 302 5.0 HO dies under load AFTER running well for a while

Things I would look at:

1. Carburetor float
2. possibility of vapor lock
3. Testing the coil when hot.
4. Fuel line air leaks
5. Fuel pump function.

Re: omc cobra 302 5.0 HO dies under load AFTER running well for a while

we have that exact boat and had a really similar problem..... we changed everything we could think of (tune-up, fuel filter, drain tank and fill with fresh gas, check seperator for water, etc....), including a new electric fuel pump. It would run great for a few minutes, but then would bog down and nut run over idle speed. last thing we did was pull the bowl off the carb, blow into the pickup tube on the tank, and check the spark advance mech for it sticking. I still have no clue what of the threee fixed the problem (non appeared to have any issue), but it runs great now.

Just some more food for thought.

Re: omc cobra 302 5.0 HO dies under load AFTER running well for a while

I had same issue with same motor. Replaced filters, fuel pump, and almost bought a new distributor. At first everyone told me it was a fuel issue. It was not! I had spark coming off of the coil, but not enough. Instead of spending 500 bucks on a distributor I decided to change the coil first, and it started up with a roar and corrected what everyone thought was a fuel issue.