Engine surging at constant speed and throttle position and

[advinnie]

Hi all I have a 72 bug with a 1600 engine in it with a pair of dell 36 carbs. Now the engine starts up fine and idles great cold and when at operating temperature but when at a constant speed/rpm and the throttle in a constant position the engine noise will chance note and it feels like it's got extra power or like it's getting a little push if that makes sense. This only happens when the engine is up to temperature. The carbs are in balance, mixtures are set.
Any help would be great
Cheers

[Jadewombat]

Probably a fuel issue it sounds like. It could be:

-The fuel cap on the tank is not venting properly, if you crack it open and hear a whooshing sound, etc.
-The sock in the bottom of the fuel tank is plugged, or fuel filter or both
-Fuel pump is not working correctly

[advinnie]

It's not a fuel issue I'm hoping. I've found an air leak between the carb and manifold on the left hand side by spraying carb cleaner but it only leaks once the engine gets up to temperature

[hwhite57]

Sounds like a bad fuel regulator. I had baby fell 36's with a electric fuel pump. I had a similar experience and it ended up being my cheap fuel regulator. Need to fix that intake leak,if it only does it when it warms up the intake manifold is warped and should be replaced. That would be my suggestion. Good luck buddy

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[Dean...]

Did you resolve this?

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[advinnie]

Yes I did it. It ended up being a bad spark plug witch was breaking down most of the time and the sudden increase in power was when it decided to work as it should so changedon't all plugs and she has been great done over 600miles in it since and the fault has not come back.

[Dean...]

That's great news!

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[advinnie]

?