fuel pressure


Well-known member
on my 1 barrel 1904 holley i'm noticing fuel coming out of a weep hole on the top front of the main body. checked the float level adjustment
and its spot on. changed the fuel pump about a year ago but this seems to be a new development. thanks, joe


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Staff member
Supporter 2021
Supporter 2019
You might want to check the fuel pressure it's been noticed that some of the new fuel pumps or rebuilts can be putting out higher fuel pressure than the the stock fuel pumps did, a fuel pressure regulator can bring that back inline. One other cause could be the fuel boiling over on a hot shut down (thanks to the modern fuels we have today) a backalite carb spacer or homemade one out of a plastic cutting board can help with that problem. Best of luck


The 1904 is an archaic design . An example of something still useful but considered obsolete. The 'weep hole' mentioned is simply the open fuel bowl vent on the carb top . The 1904 fuel bowl vent has only minor baffling to prevent fuel from leaking when sloshed around with cornering and braking. Some 1904's have a stone filter type added baffle to prevent too much fuel escaping but still the vent is often wet if not weeping. The 1904's design is from an era when a little fuel and fuel vapor escaping wasn't an important design concern.

Any fuel contamination at the inlet needle will usually cause immediate flooding on shutdown. As mentioned, a fuel pressure regulator can help prevent excessive pressure from forcing open the fuel float needle and contributing to this problem .

If you have a glass fuel bowl featured 1904, you can observe where the fuel level averages when idling and under increased pressure when revved'.

My experience has been to keep fuel level / float level / needle setting - as low as possible without reducing performance but the fuel level still rises on shutdown and still sloshes around and weeps out with any spirited driving.

( .. Original fuel bowl gaskets are cork/rubber and have continuous trouble with keeping the fuel bowl gasket sealed over time with 'modern' 10% solvent alcohol spiked gasoline. creating suitable alc/gas proof bowl gaskets remains a challenge with the 1904's.)

hav e fun

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