Engine surging at constant speed and throttle position and

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advinnie
Posts: 321
Joined: Mon Jun 10, 2013 6:54 am
Location: Oxfordshire

Engine surging at constant speed and throttle position and

Post by advinnie » Tue Jun 13, 2017 4:56 pm

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

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Jadewombat
Posts: 1245
Joined: Sat Jun 22, 2002 2:01 am
Location: Houston, TX

Re: Engine surging at constant speed and throttle position and

Post by Jadewombat » Tue Jun 13, 2017 9:15 pm

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
Posts: 321
Joined: Mon Jun 10, 2013 6:54 am
Location: Oxfordshire

Re: Engine surging at constant speed and throttle position and

Post by advinnie » Wed Jun 14, 2017 2:52 am

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
Posts: 2
Joined: Fri Jun 09, 2017 6:55 pm

Re: Engine surging at constant speed and throttle position and

Post by hwhite57 » Sat Jun 17, 2017 3:58 pm

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...
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Re: Engine surging at constant speed and throttle position and

Post by Dean... » Fri Jul 21, 2017 8:30 am

Did you resolve this?

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advinnie
Posts: 321
Joined: Mon Jun 10, 2013 6:54 am
Location: Oxfordshire

Re: Engine surging at constant speed and throttle position and

Post by advinnie » Mon Jul 24, 2017 6:58 am

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...
Posts: 124
Joined: Mon Aug 15, 2016 4:44 pm

Re: Engine surging at constant speed and throttle position and

Post by Dean... » Mon Jul 24, 2017 9:51 am

That's great news!

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advinnie
Posts: 321
Joined: Mon Jun 10, 2013 6:54 am
Location: Oxfordshire

Re: Engine surging at constant speed and throttle position and

Post by advinnie » Fri Nov 03, 2017 6:06 am

?

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