OMC cobra 4.3 engine fall out problems. Need some help please...

[Wismeijer]

Hello everyone,

I have an big problem with my Sea ray s21 (1987). When we start the boat there is no problem. The engine runs very good in idle.

On the water we give some more gas (1500rpm) no problems. When we give more gas the engine stops sometimes. This can happen at variable rmp. The engine stop immediatly. Normally he dont start after this. After a long start the engine will start and run in idle. There is an

I have no idea what to do any more. I replaced the coil, sparks, fuel filter, condensator, contact point and clean the cab. The ESA works fine.

Now im cleaning my fuel tank, maybe some water in the fuel. Im looking the whole day on google but no good luck for me.

Can anyone help me to get my boat in good conditions, so i can enjoy the weather.

Thanks to y'all
Glenn

 

[Levinz11]

Re: OMC cobra 4.3 engine fall out problems. Need some help please...

If the carb hasn't been rebuilt in awhile, do it. Check your fuel tank vent for blockage.

 

[Wismeijer]

Re: OMC cobra 4.3 engine fall out problems. Need some help please...

Hello Levinz,

The tank vent is open. Rebuilt the carb can i do. But just cleaning it? i did that last year and had the same problem.

 

[Levinz11]

Re: OMC cobra 4.3 engine fall out problems. Need some help please...

Hello Levinz,

The tank vent is open. Rebuilt the carb can i do. But just cleaning it? i did that last year and had the same problem.

When you say you've cleaned the carb...I assume you mean you just sprayed some chemical down the bores. While that may help the situation temporarily, you really need to disassemble the whole carb to clean the small fuel passages. In the carb kit will also be new check balls, gaskets, accelerator pump, filter, fuel shut off needle and other bits to make it function like new again.

If your carb is a 2 barrel unit, the rebuild is quite easy. If it's a 4 barrel, well its a little more work. OR just have a mechanic rebuild.

 

[RogersJetboat454]

Re: OMC cobra 4.3 engine fall out problems. Need some help please...

Have you tested for spark when the engine quits?

 

[Wismeijer]

Re: OMC cobra 4.3 engine fall out problems. Need some help please...

Hello guys,

Sorry for my late reaction. I was on a holiday. I tested the spark and there was a spark. I replaced the coil yesterday. Last year i put an car coil in it. Now i installed a original one. But still got the problem! Im going crazy. The weather is very good and the boat sucks.

Today we were on the water. We running about 4000 RPM with no problems for 10 minutes. And then the problem comes. The RPM is going up and down. When i gave more throttle the engine dies. I went to the harbor on 2000 RPM and after 5 minutes the engine shut down. But it will start directly. Is a carb rebuild really a option to this problem?

thank you very much for helping me

Glenn

 

[Bondo]

Re: OMC cobra 4.3 engine fall out problems. Need some help please...

Hello guys,

Sorry for my late reaction. I was on a holiday. I tested the spark and there was a spark. I replaced the coil yesterday. Last year i put an car coil in it. Now i installed a original one. But still got the problem! Im going crazy. The weather is very good and the boat sucks.

Today we were on the water. We running about 4000 RPM with no problems for 10 minutes. And then the problem comes. The RPM is going up and down. When i gave more throttle the engine dies. I went to the harbor on 2000 RPM and after 5 minutes the engine shut down. But it will start directly. Is a carb rebuild really a option to this problem?

thank you very much for helping me

Glenn

Ayuh,.... Welcome Aboard,... I donno's I'd jump right to the carb rebuild, but Testin' the fuel system would be a Great idea,...

Contents of the fuel filter,..??

Fuel flow/pressure, at the carb inlet,..??

 

[Silvertip]

Re: OMC cobra 4.3 engine fall out problems. Need some help please...

When the engine rpm begins to "go up and down" as you mentioned, that is called surging and is very likely a fuel delivery problem. I would not dig into the carburetor just yet. If it runs fine for 20 minutes or so then I doubt it is a carburetor problem. Check fuel pump pressure. When you replaced the points and condenser, cap, rotor, etc., did you set the dwell properly, then set the timing. If you didn 't do that you need to before doing anything else.

 

[Wismeijer]

Re: OMC cobra 4.3 engine fall out problems. Need some help please...

Thanks for the reactions.

What is the best way to check the fuel pump pressure? The lines to the carb. are hard and not flexible. What kind of meter can i use because i have to buy someone. t

thanks

glenn

 

[Wismeijer]

Re: OMC cobra 4.3 engine fall out problems. Need some help please...

And what about vapor lock?

 

[Bondo]

Re: OMC cobra 4.3 engine fall out problems. Need some help please...

Thanks for the reactions.

What is the best way to check the fuel pump pressure? The lines to the carb. are hard and not flexible. What kind of meter can i use because i have to buy someone. t

thanks

glenn

And what about vapor lock?

Ayuh,.... Hook a line to the fuel pump outlet, direct it to a catchcan, 'n turn it over,...
You should see a decent flow,...

Put a pressure gauge on the line, it should show 4 to 6 psi,...

To diagnose Vapor lock, run it without the motorbox,...

 

[Wismeijer]

Re: OMC cobra 4.3 engine fall out problems. Need some help please...

Hi Bon-o

today i went to buy a carb rebuild kit and a new inner filter for the carb. we were also cruising on the water and i cruise first with a closed engine box and the problem comes up. After that i open the motor box so there will be more fress air. But bad news. I put a digital meter in the box and the temp was about 40 celsius degrees. Not very high.

Also removed the anti siphon valve. still hoping on a solution...


tnx

glenn

 

[Bondo]

Re: OMC cobra 4.3 engine fall out problems. Need some help please...

Hi Bon-o

today i went to buy a carb rebuild kit and a new inner filter for the carb. we were also cruising on the water and i cruise first with a closed engine box and the problem comes up. After that i open the motor box so there will be more fress air. But bad news. I put a digital meter in the box and the temp was about 40 celsius degrees. Not very high.

Also removed the anti siphon valve. still hoping on a solution...


tnx

glenn

Ayuh,.... If yer boat ain't already equipped with a canister type filter, 'tween the Tank, 'n the Fuel pump,....

It's the Best favor you can do for yerself to Add 1,...

 

[Wismeijer]

Re: OMC cobra 4.3 engine fall out problems. Need some help please...

I already have a canister type filter.

This one is new and clean. I just rebuild the carb. And buy a anti sophin valve.

The problem comes irregular. The fuel pump can failling sometimes?