Mercruiser 454 carburetor question

[kolyo]

I finally put my boat to water and did a test run. All went well until I was back at the marina when the 454 carbed suddenly went dead quiet. It wouldn't start again and after several attempts I gave up trying. Next morning the engine started first attempt but the RPM needle was shaky and wouldn't stop trembling at the 800-2000 rpm range no matter what I did. My mechanic told me perhaps the carburetor was due for replacement. The boat is 31 years old and although the engine has a mere 400 hours on it is in a very good shape. Carburetors however tend to be affected by age regardless of engine hours, he told me and suggested I buy a replacement.

Has anyone an opinion or experience of this one: MARINE CARBURETOR ROCHESTER QUADRAJET MERCRUISER 454 7.4L V8 ENG ELECTRIC CHOKE

 

[spannerman]

Before spending your money are you sure that all is well with the ignition system, I would want to know if you still had a spark when it died. If so then it points to the fuel system, the Rochester is standard equipment on various Mercruiser engines so it will work fine, just make sure its jetted for your 454.

 

[penberth3]

…..My mechanic told me perhaps the carburetor was due for replacement. The boat is 31 years old and although the engine has a mere 400 hours on it is in a very good shape. Carburetors however tend to be affected by age regardless of engine hours, he told me and suggested I buy a replacement.....

That's sales talk, not a diagnosis. What exactly has been affected by age? Is re-build or repair an option?

 

[kolyo]

Before spending your money are you sure that all is well with the ignition system, I would want to know if you still had a spark when it died. If so then it points to the fuel system, the Rochester is standard equipment on various Mercruiser engines so it will work fine, just make sure its jetted for your 454.

Thanks for the wise advice. It does look like an electrical issue. We did extensive tests today and will continue tomorrow hoping to find the "culprit". I'll report accordingly.

 

[kolyo]

That's sales talk, not a diagnosis. What exactly has been affected by age? Is re-build or repair an option?

You are dead right, Sir. Sales talk indeed

 

[gordmac]

Is the engine misfiring? Bit more difficult to tell with so many cylinders but remove and replace each lead from the plug in turn to see if any difference in how it runs. If it makes no difference the cylinder isn't firing.

 

[kolyo]

Is the engine misfiring? Bit more difficult to tell with so many cylinders but remove and replace each lead from the plug in turn to see if any difference in how it runs. If it makes no difference the cylinder isn't firing.

Thanks for the suggestion. Unfortunately I've hurt my foot and investigation into the problem is delayed for the moment. Hope to get better soon.