Need help getting a Motorcraft 4300 to run.

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Asked by Qc_pepsi Jul 11, 2020 at 04:05 PM about the 1973 Mercury Marquis

Question type: Maintenance & Repair

hey guys! i have a 1973 mercury marquis 460 with a Motorcraft 4300 (d3vf-
ca). I have been tinkering with this carburetor for the past ~2 month but cant
get it to run. Everytime i try to start the car it floods itself (hitting it doesn't
help). iv put 3 carb kits in this thing and adjusted the float at least a few
dozen times. same thing for the idle mixture screws and idle speed. i had 2
mechanics come and take a look at it. first one played with the float alot but
never got it to run. second one came but wen he realised it was a ''460
carburetor'' told me he wouldn't even touch it. so do any of you guys have
experiences whit these carb and would be willing to let go of a few tips and
tricks? Also i really dont want to just put Holley on it and call it a day. this is
the original carburetor and as much as possible i want to keep it. Thank you!

6 Answers

Still no Joy eh Pepsi? Did you replace the float? Sometimes they get a hole in them or the foam goes bad and absorbs fuel. I would keep this carb and buy another one for the time being.

2 people found this helpful.
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yea replacing the float is probably my best bet but the friggen thing alone is around 100$. so im bidding my time hopping that someone in my area decide to get rid of a there 4300 on the cheap so i can go steal there float but so far no luck. and yea still haven't had a good ride in it this year but i still have 2 months of summer ahead of me so im still hopeful.

The float should feel light as a feather. If not it is bad.

1 people found this helpful.
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it is fairly light and i tried submerging in a gas can and nothing got into it. i will say tough the material the float is made out of feels soft, i am pretty sure that i could make a hole in it with my finger nail. i guess the material itself absorbed some gas and got heavier trough the years. argg im probably gonna give myself a kick in the butt and splurge on a brand new float.

Sounds like you have the foam type. They do go bad.

1 people found this helpful.
1,140

so i finally got fed up after opening the carb another dozen time and bought a new float! received it today. it is now installed and the carburetor no longer fload itself! but the car still wont start realised that i have very weak spark at the spark plugs so onto the next problem!

1 people found this helpful.

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