Installed new carbs, now have flames shooting out the exhaust!

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Re: Installed new carbs, now have flames shooting out the exhaust!

Post by Piledriver » Wed Aug 09, 2017 2:25 am

What is the fuel pump?
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Dean...
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Re: Installed new carbs, now have flames shooting out the exhaust!

Post by Dean... » Wed Aug 09, 2017 2:36 am

Some old electric one. I don't know the type or how old it is.

I bought a new pump an hour ago, and a new adjustable regulator made by Redline. I also bought some new lever arms which I'm installing now so I can be sure that the carbs have the exact same geometry.

Starting to get dark now though, so probably won't get far.

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Re: Installed new carbs, now have flames shooting out the exhaust!

Post by SCOTTRODS » Wed Aug 09, 2017 6:19 am

Fuel pump may be *an* issue... but low fuel pressure and flow, will not create a rich mixture issue... There would be very white spark plugs at that point... white powdery electrodes and ground tab... Sooty Spark comes from too much fuel... Did I miss a post somewhere about a bigger change to spark plug appearance?
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Re: Installed new carbs, now have flames shooting out the exhaust!

Post by Dean... » Wed Aug 09, 2017 3:28 pm

I got the plugs going white by getting the idle mixture right. So at least when the idle circuit is running, the mixture is good now.

So I'm wondering that with the fuel pressure dropping to below 1 psi when revving it, it could mean that the fuel bowls are not stable and that's why it's running bad when it's revved.

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Re: Installed new carbs, now have flames shooting out the exhaust!

Post by Piledriver » Wed Aug 09, 2017 4:33 pm

Without a wideband O2 sensor, you are limited to plug readings, are averages at best.
Depending on the fuel, reading plugs can be worse than useless.
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Re: Installed new carbs, now have flames shooting out the exhaust!

Post by Dean... » Wed Aug 09, 2017 5:17 pm

Yes, averages. I don't know if you saw the videos, but the engine doesn't want to rev, so the the plugs are really only showing what the average is from idle to about 2500.

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Re: Installed new carbs, now have flames shooting out the exhaust!

Post by Dean... » Thu Aug 10, 2017 12:43 am

Ok, this is where I am now....

The engine seems to be running not too badly, but I haven't driven it yet, just revving it at this stage and there is a huge improvement. But....

I installed the new fuel pump, which max pressure is 3.0-4.5. I did buy a new regulator but the mongrel won't stop leaking at the threads where the fuel barb is screwed. I then tried the old regulator, but the pressure gauge was still showing very low pressure, so I've set it all up with no regulator. The stupid thing is that the gauge is still reading pretty low! Anyways, the plan is to get the new regulator to stop leaking and use it, but that's for another day.

What I have learnt is how sensitive the mixture screws are, which makes me wonder if they are a tad rich. I and really beginning to think that it's always been the idle mixture and I kept setting it a little too rich, not realising how sensitive they adjustments are. I'm wondering if I should go down a half step: it's running 55 but I have 52.

I'm very keen to hear what you think about the idle jets. To recap, the setup is 44 Webers with 34 vents, 55 idles at present and 145 mains. I also have a set of 125 mains and 115 mains, but from what I've read, 145's should be good. Tubes are F11.

Thanks
Dean

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Re: Installed new carbs, now have flames shooting out the exhaust!

Post by Piledriver » Thu Aug 10, 2017 1:29 am

Permatex or Locktite anaerobic thread sealant with Teflon is your friend for sealing pipe threads.

How far out are the fuel screws when you have it adjusted for best lean idle?
That alone will tell you if you need larger or smaller idle jets.

More than 2 turns out, you need to go larger.
Less than 1/2 turn from cracked probably needs smaller, but it can work fine perfectly like that.

55/135/200/F11 is bog std on 44/36ss, you are just running one size smaller venturi.
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Re: Installed new carbs, now have flames shooting out the exhaust!

Post by Dean... » Thu Aug 10, 2017 1:46 am

Thanks for your reply!

I had some thread sealant, so that jobs done.

I'll have to check on how far the screws are out. I'll check soon and share.

The stock sizes is interesting... I might try and 125's that I have, maybe.

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Re: Installed new carbs, now have flames shooting out the exhaust!

Post by Dean... » Thu Aug 10, 2017 2:13 am

I just checked the mixture screws, and they are between 1 and 1.5 turns out.

I think I'm going to go down to the 52's. Some instructions I've read talk about turning the screw 1/8 of a turn at a time, but I'm having to turn them something like 1/32 to really get the feel for it. I'm finding there isn't much in it between rubbing lean and missing to bogging due to being rich. With the smaller jets I'm hoping the adjustments won't be so fine.

I also think getting the geometry better with the linkages probably made a big difference. I even used spacers.

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Re: Installed new carbs, now have flames shooting out the exhaust!

Post by Dean... » Thu Aug 10, 2017 3:20 am

I found this on air-cooled.net. Is it correct that I need to find where it runs the smoothest and then screw it out ANOTHER HALF A TURN? [IMG]//uploads.tapatalk-cdn.com/201708 ... 07d1b6.jpg[/IMG]

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Re: Installed new carbs, now have flames shooting out the exhaust!

Post by Piledriver » Thu Aug 10, 2017 12:11 pm

....No. Just No.

I suggest using the official Weber procedure...
http://www.carburetion.com/Weber/adjust.htm
It's basically the same procedure for all Weber (and almost all other) carbs.

As to linkage woes, there is only one setup I can recommend without hand waving...
A Synclink (or roll your own along the same lines)
https://www.thesamba.com/vw/classifieds ... id=1381017
Words fail to describe well enough how much suck most other setups have (esp the hexbar), but you have probably experienced it yourself.
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Re: Installed new carbs, now have flames shooting out the exhaust!

Post by Dean... » Thu Aug 10, 2017 4:20 pm

Cool, thanks for the reply. I try to stick to VW specific instructions, which is why I was using that guide as a reference, but the real instructions I was trying to follow are very similar to yours : http://www.redlineweber.com/html/Tech/i ... ntrols.htm

I like that linkage!!! I'll be considering purchasing them, pity about the exchange rate lol

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Re: Installed new carbs, now have flames shooting out the exhaust!

Post by Dean... » Fri Aug 11, 2017 1:03 am

This is absolutely driving me crazy!!!!!

When sitting in the driveway revving the motor, it goes sweet as.. Take it for a drive, and it feels like it's running on 1 cylinder, it just won't rev. I pull over, and it idles sweet, but initially it won't rev, it has to idle for a time before it will rev nice again. This makes me feel it's lean. I also noticed that while pulling over, the exhaust is popping. The fuel pressure gauge is saying that it pretty much has no pressure.

Do the fuel tanks have a filter inside them? I needed fuel for the lawn mower some time ago so I siphoned some out of my tank and the hose must have hit the fuel level sender because the float part is not connected. Any chance it could be getting in the way of the fuel flow? I'm doubting this. When I replaced the fuel pump, the fuel had no problem flowing out the tank, but things might be different when under pressure.

Or maybe it's the carbs. I don't know how this would be the case, but the issue has to be fuel related and I'm running out of possibilities.

So this is the plan.... I'm not going to be able to do any work until Sunday. The first thing I'll do is disconnect the fuel pump from the fuel tank and I'll get it to draw fuel from a bottle. If I have the same issue, then I'll take off the carbs and put on another set. I just can't understand that it could be the carbs, but there are not many other possibilities.

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Re: Installed new carbs, now have flames shooting out the exhaust!

Post by Piledriver » Fri Aug 11, 2017 1:57 am

There's actually a "sock" fuel strainer thats supposed to be in the tank, rust can also build up over the years in the line causing all sorts of interesting times.

Take the gas cap off and verify you can blow through the line into the tank.

Note if you have a tank vent issue and forget to take the cap off, it will spray fuel back at you when you stop blowing..
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