Fuel pump capacity

[enemy]

Just replaced my stock motor and I’m wondering if the stock belt driven mechanical fuel pump will be sufficient for the new motor or if I need to replace it. It’s from a 98 454 merc 300 hp and I put in a 500ish hp carb motor. If I should replace it will just any after market mechanical pump work or does it need to be something special with the belt drive. Looks like the same thing to me but haven’t pulled it off to see.

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[Riverbottom]

Any marine Big Block Chevrolet pump will work. I would look carefully at the inside diameter of all those bass fittings. Some of them can be petty restrictive.

 

[enemy]

Thanks. So are you saying I should replace the fuel pump then? I am replacing all the fuel lines and fittings with braided and AN fittings just temped it up to start it.


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[Riverbottom]

If it is really 22 years old, I would replace it. Just my opinion.

 

[enemy]

Haha ya good point. I already have a new one lol


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[28Eliminator]

Any marine Big Block Chevrolet pump will work. I would look carefully at the inside diameter of all those bass fittings. Some of them can be petty restrictive.

Not ANY pump will work. the Water pump driven Gen V/VI pump has a proprietary arm designed only to work for the Water pump/fuel pump provision.

 

[enemy]

Not ANY pump will work. the Water pump driven Gen V/VI pump has a proprietary arm designed only to work for the Water pump/fuel pump provision.

Oh shit. Thanks for pointing that out. Is what I have one of those or can you tell me how to check?


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[Kylemenz1]

Yes you have one.

Is your new motor a GEN VI block? If so get a new fuel pump that fits your current setup.

If it is not a GEN VI block it should have a provision for the mechanical fuel pump on the block. Then you would not need your current setup.

The fuel pump setup you have is because the block you’ve got was meant for vehicles with electric fuel pumps. No big deal, just get the correct fuel pump for it and you’ll be fine.

!!!DON’T FORGET TO ADD OIL TO THE FUEL PUMP HOUSING IF YOU KEEP IT!!!

Ask me how I know how important that little detail is!?! If you forget to add oil the whole unit will seize. You’ll be stuck on the water and out $1000.00 to replace it.


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[28Eliminator]

Oh shit. Thanks for pointing that out. Is what I have one of those or can you tell me how to check?


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Yes, thats what you have. Merc only makes 1 fuel pump for that set up, and its the same one used for the HP500 as well, so it will be plenty for your future set up.

 

[enemy]

The new motor is actually a mark IV block so it will accept a mechanical pump but the pump housing is in the way so I’m stuck using the belt driven one or going to an electric. Thanks for the heads up about the oil. Don’t want to learn that lesson the hard way.


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