Manx Club

After my buggy (with a 1600 and a brand new carb - dual barrel) warms up pretty good, if I load it up, like going up a hill or just goosing the throttle, it dies. If I'm just goosing it, it sputters for a second and then comes back to life, if it's a longer hill, it's coughing and choking by the top... then dies. If I give it a minute, it starts up and will go again - as long as I baby it. After a stretch of moderate acceleration (or just steady speed at medium rpm), it idles really high... my very untrained mechanical sense says that means it's running lean. ? .. but when it sputters and comes back to life, it usually comes back with a bang... like it's running rich. ? maybe the plugs got fouled somehow? I'm no mechanic... just giving that info as FYI. I just had it tuned, new points, new plugs, valve adjustment, new fuel filter, new (rebuilt) fuel pump, some new fuel hose, and had the compression and timing checked. I'm weary of taking it back to the same guy because it's been in his shop three times now and is still not running properly. The carb is still pretty new only has maybe 2-3 hours on it... Does this sound like a tuning problem? Fuel delivery problem? Some other problem? I just bought this thing, btw. I've driven it maybe 6 times, two of which had it had to be towed back to the mechanic, 2 other times it died on a busy street. This thing is getting expensive.... kinda discouraging.

Is it iceing up? Does the manifold have a heat tube?

If by "iceing" you really mean freezing water.... I don't think it's been below freezing here in years. ;o) It certainly hasn't been since I've owned the buggy.

The intake manifold will ice up just below the carburetor, from the air moving thru the intake at high velocity. VW installed a tube on the intake manifold that runs from the rear exhaust port on one side of the engine to the exhaust port on the other side of the engine. This heat tube is supposed to heat the manifold to prevent iceing and keep the fuel in suspension so the engine will continue to run smoothly.

[QUOTE="newmanx59"]The intake manifold will ice up just below the carburetor, from the air moving thru the intake at high velocity. VW installed a tube on the intake manifold that runs from the rear exhaust port on one side of the engine to the exhaust port on the other side of the engine. This heat tube is supposed to heat the manifold to prevent iceing and keep the fuel in suspension so the engine will continue to run smoothly.[/QUOTE] ahh... ya learn something new every day. I will look into it. Thanks!

Did the problem start with the new carb install??? It would narrow things down a bit. Float level also comes to mind.

I'll take a wild guess... Is this a Weber Progressive?

Can't say that the problem happened with the carb install because I didn't install it. It was put on by the previous owner just before he sold it to me. He seemed to think it was running good... and it does for a few minutes - or at idle for quite a while. What Kind of carb... hmm... not sure. I just sent him (the previous owner) an e-mail asking. In the mean time, here's a pic:

I dont think carburetor icing is much of a problem in southern california, at least I have never had a problem with it. Need to determine if the problem is fuelrelated or not. When it dies, go back to the carburetor and manually pump it as you look down into the carburetor, is fuel being squirted by the accelerator pump? If so,then you have gas at the carburetor, if not, then there is a problem with your fuel supply. Can also be that its flooding, in which case you might see signs of that, when it restarts, is there a big cloud of smoke? I recently had a problem with my buggy where it would intermittingly run, sometimes well for a while, then die, and had to crank over for a while, and then it might run well for a while. Turned out to be a float valve sticking closed, wouldnt always allow the bowl to fill up with fuel. If you decide that its fuel related I would check the float setting, as well as the float valve, to make sure its operating properly. You say that it idles well, so then its not a clogged idle jet, or a vaccum leak. Can also be something with the electrical, loose coil wire,or even grease on the points if you have points. I noticed the carburetor says made in china, I believe thats a relatively new model, has it ever run on this engine? Has it been set up for this engine?

[QUOTE="joemama"]I noticed the carburetor says made in china, I believe thats a relatively new model, has it ever run on this engine? Has it been set up for this engine?[/QUOTE] Thanks for the info. I'll check it this weekend when I have time to be stranded. In answer to your questions - it (the carb) was purchased new just before I bought the car. The previous owner said it had "about an hour on it" when I got the car. The first visit to the mechanic was to tune it (because it came from a higher altitude), so I would say it is setup for this engine. My mechanic (who has been working on air cooled VW's since '74) said that I would benefit from a better distributor. He said that he had it advanced as far as it would advance, but it could still use some more. Don't know if that has anything to do with anything. Once it dies, if I give it a second (with the fuel pump running, if that makes any difference), it starts right back up - one or two cranks.... and it idles really high. The tach is not working, but by pitch of the motor, I'd say close to 2K rpm at idle. TO be honest, I've never looked back to see if there was a big cloud of smoke, but I haven't smelled anything overly gassy on restart. If I let it idle for a bit, it calms down until I drive it for a while - then high idle again. This makes me think it's not getting gas... granted, I haven't had to tune a carb in at least a hundred years so I really have no idea what I'm talking about. Oh, and I just heard back from the owner - it's an Empi 40mm. Thanks for all the replies.

I think I would ask the mechanic why he set up the idle so high. If it has purposely been adjusted to idle this high, its probably because its the only way to keep the engine running, possibly indicating a large vaccum leak, or something wrong with the idle circuit on the carb. I find it unusual that the fuel pump would be rebuilt and not just a new one put on, is it electric?

Ah, a new Empi HPMX. Why is the filter base not installed correctly? Or was that just a pic before the filter base was installed. Your issues sound fuel related to me. Single downdrafts can be a bear to tune correctly. Intake pre-heat is almost a must.

I have the DRLA40 single 2 barrell carb on mine engine and did have a similar issue. I had a bit of a rough idle and it would load up at lights. I found that smaller idle jets helped it a TON!!! I originally had 60's and now run 55's. I am still playing with the jetting and the blend screws but it's way better now. Also I found that shutting the bypass screws all the way made a differance. I do not know the long term effect of shutting these but the motor runs better with them closed and the smell of fuel dissapears at idle. It seems to me that the single 2 barrel cars will run a bit rough at idle no matter what you do. When I took it to a local mechanic who works on air cooled engines his advice to me was "learn to live with rough idle or switch to a single barrel or dual carbs." I would like to note the engine runs awesome under power and over 1000 RPM's. My:2cents: Hey Uncle Bob is there a kit to heat the intakes? I do not think mine are heated now.

Most Weber IDF manifolds come with heater tubes and 90% of the owners cut them off of the chrome manifolds and just don't use them on the cast manifolds. They make a huge difference in the way the engine runs and fuel economy. I would say you probably have 2 issues: 1- The carb has not been tuned for your engine. 2- The mechanic you are bringing your buggy to does not know how to to tune a Weber carb and won't admit it. I would find a shop that is known for the ability to tune VW's With Weber carbs or if you are up to it, buy the Weber tuning manual from CB Performance read it and understand it then tune it yourself.