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Ossipon
Samba Member
Joined: May 12, 2021
Posts: 605
Location: KS
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 Posted: Sun May 04, 2025 1:26 pm Post subject: recent intake backfire. |
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The right side carb has developed a "light" intake backfire when accelerating. It happens with the initial punch of the accelerator cable. If I try again, with acceleration, no issue. There is no jutter in the timing when increased engine speed and drop to idle, Carbs are balanced
It is a stock 1600 with stock Dual Solex. Nothing major other than oil change recently. idling about 800.
I would put it down to a condenser or Lean fuel mix, but Condenser is not that old and carb when visually inspected it looks normal.
Any ideas?
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Ossipon
--Two truths in life: Volkswagens Rust and everything will die at some point --
VWs in my life:
Air
Type 1 - 59, 62, 63, 71 Super 68 KGhia/ Type 2 - 59 Single Cab / Type 3 - 64 Notch
Water
GTI 83, Jetta 81, 85, 87, 91 TDI, 98 TDI, 09 / New Beetle 99 / SportWagen 05, 13 / Tiguan 18 / T3 92 /Taos 24... And don't about me and my experiences with my Dasher and Quantum |
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Mike Fisher
Samba Member
Joined: January 30, 2006
Posts: 18041
Location: Eugene, OR
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| Posted: Sun May 04, 2025 2:19 pm Post subject: Re: recent intake backfire. |
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Brian Fye told us backfires were caused by improper balance/sync between the carburetors.
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69 FI/AT square Daily Driver
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sjbartnik
Samba Member
Joined: September 01, 2011
Posts: 6041
Location: Brooklyn
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| Posted: Sun May 04, 2025 2:33 pm Post subject: Re: recent intake backfire. |
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Could also be caused by an intake valve on that side that no longer seals well, whether via wear or improper valve adjustment.
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Ossipon
Samba Member
Joined: May 12, 2021
Posts: 605
Location: KS
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| Posted: Sun May 04, 2025 3:13 pm Post subject: Re: recent intake backfire. |
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Update...
Just to cover my bases, I checked the balance. And behold the right was way off. I then sprayed a bit of ether around the junction points of the right side. There was a noticeable speed difference when I sprayed around the balance tube. connector. Unfortunately I did not have that size of rubber/cloth tube in my inventory. Who knew.
As a temporary fix, I removed and sprayed the woven rubber tube on the outside with liquid rubber (Like you see on late night TV) Let it dry and installed it with crossed fingers. Carb balance is acceptable again and am hoping this will work as I wait for a replacement.
Hopefully ISP has them in stock
Your recommendations were spot on.
_________________
Ossipon
--Two truths in life: Volkswagens Rust and everything will die at some point --
VWs in my life:
Air
Type 1 - 59, 62, 63, 71 Super 68 KGhia/ Type 2 - 59 Single Cab / Type 3 - 64 Notch
Water
GTI 83, Jetta 81, 85, 87, 91 TDI, 98 TDI, 09 / New Beetle 99 / SportWagen 05, 13 / Tiguan 18 / T3 92 /Taos 24... And don't about me and my experiences with my Dasher and Quantum |
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