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1974 VW Bug not running with Choke plate upright
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AfroBugMan
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PostPosted: Mon Jul 18, 2016 3:07 am    Post subject: 1974 VW Bug not running with Choke plate upright Reply with quote

My 1974 bug, with a dual port 31PCIT carb. She will not run with the choke plate open at up right position. She gets more power with the plate at shut position. Even though she gets power with the plate shut, she produces black smoke and fuel consumption is too high. I have put in a 34PCIT dual carb, this one too could not give her power with the choke plate in the up right open position, she would only fire properly with the plate shut. The idling is sweet and normal and no isssues with engine start. What should I do.
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ashman40
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PostPosted: Mon Jul 18, 2016 12:35 pm    Post subject: Re: 1974 VW Bug not running with Choke plate upright Reply with quote

You have a vacuum leak that is creating a lean condition when the choke butterfly is fully open. While the plate is (partially) closed it richens the mixture and the engine runs smoothly. This is also why you are blowing black smoke.

Check the common places for a leak:
    intake boots
    manifold gaskets
    carb to intake gasket
    vacuum hoses
    carb throttle shaft bushings

Using carb cleaner in a spray can, hit all of the above points while your have the engine idling (on the lowest step of the cam that it will reliably idle). Use the straw that comes with the can so you can pin-point where you are spraying. The throttle shafts are the hardest as you need to place the straw right where the throttle arm and the carb body come together.
Any change in rpms (up or down) when you spray indicates a leak. The carb cleaner gets sucked into the intake and impacts the rpms. Small leaks will go up in rpms when the carb cleaner richens the mixture. Large leaks can drop the rpms as you flood the mixture.
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'67 Beetle #1 {project car that never made it to the road Sad }
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'67 Beetle #2 {2019 project car - Wish me luck!}
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Danwvw
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PostPosted: Mon Jul 18, 2016 12:59 pm    Post subject: Re: 1974 VW Bug not running with Choke plate upright Reply with quote

Don't drive it that way, Needs to have a gasket or something. How do you have a Pict 34 as dual carbs? Photo?
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Chochobeef
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PostPosted: Mon Jul 18, 2016 1:43 pm    Post subject: Re: 1974 VW Bug not running with Choke plate upright Reply with quote

Probably dual port, not dual carb. That is my guess without pictures.

Ashman's got my vote. You have a busted gasket, uncapped vacuum port and/or the throttle bushes are worn.
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AfroBugMan
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PostPosted: Tue Jul 19, 2016 1:42 am    Post subject: Re: 1974 VW Bug not running with Choke plate upright Reply with quote

The carb is dual port, I sprayed carb cleaner on all suspected air leak areas, the ravs dropped on the left side intake side. The intake was not properly secured to the head, tightened the screws and there is considerable improvement in engine performance, but still will not run with the choke butterfly wide open. Will repeat the carb cleaner spray procedure and hopefully will identify the leak
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AfroBugMan
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PostPosted: Tue Jul 19, 2016 1:51 am    Post subject: Re: 1974 VW Bug not running with Choke plate upright Reply with quote

what does uncapped vacuum port means,please explain to me
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zoobyshoe
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PostPosted: Tue Jul 19, 2016 2:52 am    Post subject: Re: 1974 VW Bug not running with Choke plate upright Reply with quote

That's a pretty beetle. I am surprised to find out there is a Beetle in Zimbabwe. Were they sold there back in the days they were still being made? Or did it come up from South Africa, perhaps?

I think people would like to see pictures of your engine, especially the carburetor. Close ups from left, rear, and right would give the most information.
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ashman40
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PostPosted: Tue Jul 19, 2016 5:16 am    Post subject: Re: 1974 VW Bug not running with Choke plate upright Reply with quote

AfroBugMan wrote:
what does uncapped vacuum port means

Here is a pic of a Solex carb, notice the black rubber caps on the unused vacuum ports. If any are missing (port uncapped) you end up with a large vacuum leak. All Solex carbs will have a vacuum port on the left side (distributor vacuum advance port) but will have various number of rear facing ports. This one has three, some have two, one or none.
Image may have been reduced in size. Click image to view fullscreen.

Also look for port opening where the brass tube has fallen loose. Sometimes there is a hole and it looks like a tube may have been, but the hole is cast that way and no tube was ever installed there. This carb has two holes but neither is an active vacuum port. They were cast but never drilled. Check if you feel vacuum at the port both at idle and at higher rpms. If you don't feel vacuum you can ignore the hole.
Image may have been reduced in size. Click image to view fullscreen.

The arrow indicates a round plate that often comes loose and creates a big vacuum leak. Check that this is not missing.
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'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}
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Chochobeef
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PostPosted: Tue Jul 19, 2016 5:53 am    Post subject: Re: 1974 VW Bug not running with Choke plate upright Reply with quote

zoobyshoe wrote:
That's a pretty beetle. I am surprised to find out there is a Beetle in Zimbabwe. Were they sold there back in the days they were still being made? Or did it come up from South Africa, perhaps?

I think people would like to see pictures of your engine, especially the carburetor. Close ups from left, rear, and right would give the most information.


I like pictures. Very Happy

Can definitely get more help with them.
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AfroBugMan
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PostPosted: Tue Jul 19, 2016 8:53 am    Post subject: Re: 1974 VW Bug not running with Choke plate upright Reply with quote

Thank you Ashman40 and all you guys. I am sure in a few days when I fly back to Zimbabwe, saturday this week actually, I will fix the problem. The carb looks axactly with the pics from from Ashman40. On mine,There are two vacuum tubes going to the air filter, the third one is capped by a black cap. Do i need to cap or block the other two with tubes going to the air cleaner?. Do I need to block the other vacuum outlet to the distributor and remove the tube,?

Zimbabwe has a long history of association with beetles, they were at some point made here I think, but largely imported from accross the border in South Africa. My dad owned a beetle, way back in 1970 when I was 6 years old. We keep them going, its amazing what we do to keep them going. We are clever in that we use recycled material, from scrap yards to fix the cars, we also have a few parts shops selling vw beetle parts, so we are cool here.
I own three vw beetles, and a variant notch back. I drive my beetles any distance I want with no problems.
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Chochobeef
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PostPosted: Tue Jul 19, 2016 9:45 am    Post subject: Re: 1974 VW Bug not running with Choke plate upright Reply with quote

Sweet. I dig the black/green color combo.

Lets see what you got first before we make to many more suggestions/assumptions about your current setup. One final thing is your current hoses could be the culprit in they are not sealing properly.

Be safe in your travels.
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ashman40
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PostPosted: Tue Jul 19, 2016 3:55 pm    Post subject: Re: 1974 VW Bug not running with Choke plate upright Reply with quote

AfroBugMan wrote:
On mine,There are two vacuum tubes going to the air filter, the third one is capped by a black cap. Do i need to cap or block the other two with tubes going to the air cleaner?. Do I need to block the other vacuum outlet to the distributor and remove the tube,?

I'm not sure what you are asking here? If the vacuum hoses are connected to something like the air cleaner or the distributor they are there for a reason, why would you want to remove the hose and cap the carb port? If they are broken or no longer needed, then YES you MUST cap them.

Any unused open port is a vacuum leak... which is what Chochobeef meant when he mentioned "uncapped vacuum port" as a possible source for a vacuum leak.

Also, some models had a vacuum port on the intake manifold. It was usually on the left side of the "neck" below the carb or on the end castings above the cylinders.
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AshMan40
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'67 Beetle #1 {project car that never made it to the road Sad }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}
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AfroBugMan
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PostPosted: Tue Jul 19, 2016 11:54 pm    Post subject: Re: 1974 VW Bug not running with Choke plate upright Reply with quote

Thank you guys, I will post the pics of the carb when I am back home in Zimbabwe on saturday this week.
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AfroBugMan
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PostPosted: Mon Jul 25, 2016 5:16 am    Post subject: Re: 1974 VW Bug not running with Choke plate upright Reply with quote

Hello guys, thank you to you all , the bug is now running ok . The gasket that seats between the carb and intake manifold was sucking in air, had it replaced and the carb is now firing normally. On saturday I Drove from Harare, the capital of Zimbabwe to Mutare, a distance of 266 km one way and back to Harare on sunday and she performed very well. The break paddle was hard with no free play, I adjusted the nut on the rod on the brake paddle and it works properly now.
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