back fire on accelration

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Vintage man
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back fire on accelration

Post by Vintage man »

Hi all
Where to start ,1600 TP motor in a late bay.
When accelerating jerks and power low then it back fires.It started doing this and then cleared but this weekend no luck.Checked the timing and dwell angle and that is spot on.


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John Alves
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Re: back fire on accelration

Post by John Alves »

when does this happen? engine cold? engine hot? all the time? does it happen on deceleration as well?
touch the exhausts see which one is cooler than the rest, possible bad plug??
No sense being pessimistic. It wouldn't work anyway.

1958 1600 TP Karmann Ghia
1968 1600 TP Beamish buggy
1968 1500 SP Beetle
Vintage man
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Re: back fire on accelration

Post by Vintage man »

All the time ,seems only on acceleration .will check plugs and leads as soon as I get a chance.Will check the exhausts as well.Thanks
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Eugene
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Re: back fire on accelration

Post by Eugene »

No...let John come feel the damn exhausts :twisted:
You can never have enough Garages :-(
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Tony Z
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Re: back fire on accelration

Post by Tony Z »

sounds like the pump jet isnt working as it should
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Re: back fire on accelration

Post by Vintage man »

Hi Tony ,I will check the pump jet system but it also does it a constant acceleration.Nothing on de-acceleration.
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Re: back fire on accelration

Post by 73type2 »

I had a similar issue on my '71 Beetle. I found a leak on the intake manifold.
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Tony Z
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Re: back fire on accelration

Post by Tony Z »

Vintage man wrote: Tue May 29, 2018 11:38 am Hi Tony ,I will check the pump jet system but it also does it a constant acceleration.Nothing on de-acceleration.
Then likely a vacuum leak
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Tony Z
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Re: back fire on accelration

Post by Tony Z »

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John Alves
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Re: back fire on accelration

Post by John Alves »

Eugene wrote: Tue May 29, 2018 9:22 am No...let John come feel the damn exhausts :twisted:
I now have a laser temp gauge so no more finger burns :)
No sense being pessimistic. It wouldn't work anyway.

1958 1600 TP Karmann Ghia
1968 1600 TP Beamish buggy
1968 1500 SP Beetle
Vintage man
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Re: back fire on accelration

Post by Vintage man »

ok so what temp should it read
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John Alves
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Re: back fire on accelration

Post by John Alves »

the colder one would be the one with the misfire (if the problem is plug related)
No sense being pessimistic. It wouldn't work anyway.

1958 1600 TP Karmann Ghia
1968 1600 TP Beamish buggy
1968 1500 SP Beetle
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Re: back fire on accelration

Post by Terry Phillips »

Sucking air use the old hair spray trick, my 2c.
I think I was barking up the wrong tree.I was thinking of de acceleration. :oops:
Last edited by Terry Phillips on Sun Jun 10, 2018 11:03 pm, edited 1 time in total.
Vintage man
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Re: back fire on accelration

Post by Vintage man »

Reset the volume and bypass on the carb as per Google and runs smooths. Out on the highway and a bit of town driving, I'm chuffed, Thanks all that gave advice as I did do as adviced as well so another learning my bus.
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