1600 CC, N/A, nearly all stock, Bosch 009 distributor, new carb, timing set per specs, mixture adjusted per specs... idles smoothly, however it loses power when accelerating...sometimes.  Tends to bog down at low RPM, basically making it impossible to drive at 5-10mph.  If i apply throttle with no load on the engine (in neutral) and hold it constant, the RPMs after a few moments, will tend to decline without any change in throttle position and the engine begins to run rough.  If i do not make any further correction with the throttle, the engine dies.  But if i let off the throttle, it goes back to idle and is quite happy there.

 

I have pulled off the oil bath air cleaner, and peered into the carb barrel as i pull the throttle, and can clearly see a nice smooth stream of fuel being injected down the barrel so i dont suspect the accel pump.  I'm pretty sure i've got all the vacuum lines either blocked off or attached correctly.

 

Im not sure if im missing something obvious, or if i just need to spend some extra time fiddling with the timing/mixture settings.  Any suggestions or insights are much appreciated, thanks. 

 

Quote 0 0
MY72BUG
Hi 3DE and welcome to the world of V.W.   Long distance troubleshooting can be a challenge.  When I read ones like this, I would like nothing more than to drive over and run a whole series of " what if I " tests on the car.  You have a new stock carb, have you checked out some VW DIY books to do the set up?  I'm thinking a fuel problem just from the sounds of your description of the problem.  Check the quality and quantity of your fuel flow from the tank to the fuel pump and from the fuel pump to the carb.  If there is umpteen years worth of sediment and crap in your tank and in the fuel line you could experience the problem you describe.  A weak or sticking fuel pump may happily supply the carb at idle but when the action picks up the carb starves as the fuel flow fails to keep up the pace.  Watch for crimps in lines.  At one point I had a no run problem that I traced to the line as it left the tank.  The flow was all but shut off altogether.  Do you have the original screen type fuel filtre in the pump?  An awful lot of bug owners replace these with a clear in-line type of filtre.  I can't think of any specific eletrical problems which would give you the symptoms you describe but be aware that if you are running any vacuum lines or have any vacuum sources blocked off,  a poor fitting line or a pin hole somewhere can cause no end of fun and games affecting acceleration, idle and power.  Good luck with the project.  Consider buying a Haynes book or the John Muir book,
"How to Keep Your Volkswagen Alive ".  There are sections in each of them which will help you troubleshoot your engine.   MY 72 BUG

I'd rather have a partial bottle in front of me than a partial frontal lobotomy.
Quote 0 0
Juju

I am with MyBug on this one. It appears lack of fuel is the culprit. On my 74 Super there is an in line filter right at the bottom of the gas tank on the front of the car. If it is half plugged with sediment it could cause your grief, or the filter in the engine compartment as Dan mentioned. Both are worth changing.  Good luck 

Quote 0 0
Juju

I was thinking about this problem further last night.  If you pull the fuel line off at the fuel pump and plug it so it doesnt drain all over you, you could get a piece of fuel line hose about 4 feet long (Attach it to the pump)and a gallon can of gas and try letting the fuel pump draw from the gas can, with the engine rev'ed up.  If that works, you know that the fuel source from the tank is not adequate.  If it does not work then you know it is a faulty fuel pump or carburetor.  If you try this, have someone hold the gas can up higher than the fuel pump so you get some gravity fuel feed and some siphoning action similar to the actual conditions of the tank in the vehicle when you do get the engine running and the pump is actually pumping the fuel. Also you might try running the engine with the fuel tank cap off. If the cap vent is plugged and not enough air is getting in, the fuel is not getting out fast enough. 

Quote 0 0

my 1641 bogs on take off whats up?

Quote 0 0

this is yohan again my engine is a new 1641 new points ,distributer,timing is set where it runs best i have screwed with the carb a lot rebuilt it adjusted it when i take off i have to rev it and slip the clutch or it bogs out i cannot find any vacuum leaks all the plugs and wires and cap,rotor coil are new ive tried premium gas in it too and still it bogs is my carb just crappy or what? the car is a 74 baja with 30.9.50 15 rear tires is there a problem there? please help!!

Quote 0 0
MY72BUG
This is just a long shot but have you checked that your plug wires are on in the right order?  Your firing order is 1-4-3-2.  That is the "Zundfolge" cast into the base of the alternator/ generator stand.  Watch the direction that your rotor travels.  Note your timing mark on the pulley for the number one cylinder and proceed from there.  Your passenger side cylinder closest to the front of the car is #1.  The passenger side cylinder closest to the rear of the car is #2.  The driver's side toward the front is #3 and the driver's side toward the rear is #4.  A couple of years ago, I brought my car out of storage and installed all new plug wires, plugs and distributor cap.  At the end of a long day I quickly put everything together and left for my first test drive of the season.  I must have pictured the rotor turning in the incorrect direction because I switched my #2 and #4.  The car had no acceleration, performing much like you describe your car.  Two of the four cylinders were receiving their spark at the wrong time.  I drove home, pondered for a minute and reworked my wiring.  Voila !  Problem solved.   Failing this, is your distributor advancing?  If it is a vacuum model, try a vacuum gauge to make sure that a line isn't plugged.  If it is a centrifugal type, make sure that the mechanism is free.  I still suspect carburetion.  I found three different approaches  in three different books for setting up my PICT 34.  I hope that this is of some assistance to you.   MY 72 BUG
I'd rather have a partial bottle in front of me than a partial frontal lobotomy.
Quote 0 0

hey my 72 bug all the wiring is correct it runs great its only boging on take off i also feel it is carb issues althuogh i want to be sure if i am gonna replace it with something else.How is the progressive webber? it costs about as much as a stock 34pict3 does, but i get 2 barrells instead of one! ive heard they are junk is that true? chow for now 

Quote 0 0
MY72BUG
Hmmm.  I can't help you on other carbs.  My all stock set up Pict carb accelerates quite nicely aside from the slight hesitation imposed by the slower advance of the 009 distributor.  You must remember that the addition of different carburetion is a fine science which in turn imposes unanticipated stresses on the engine such as making it run hotter.  I don't know enough about this fine science other than performance boost on old engines comes at a price.  You have to be prepared to beef up other engine components and to pay a price in terms of durability.   I keep thinking that there must be a carburetion problem.  Look in the venturi of the carb for a series of very fine double holes.  These must be free of any varnish deposits.  I used a dental pick and a piece of super fine stainless steel fishing line to clean these out.  That and the repositioning of the accelerator plate ( I had it intalled backwards) cured my PICT.  Good luck with the project.  MY 72 BUG
I'd rather have a partial bottle in front of me than a partial frontal lobotomy.
Quote 0 0

someone told me that my pre heater tubes were the problem so i changed my manifold and still no go, it does not bog when the revs are up and ive tried three different carbs im ready to buy a ford right about now

Quote 0 0
luftgekuhlt
Yohan are you sure that the distributor is the one that came with that engine. I have a 75 T1 that I bought and the engine was out of a 71 but I checked the numbers and the distributor was a brand new from Mexico. here's a link to check http://www.oldvolkshome.com/ignition.htm
because I went buy the manual for mine and had similar problems.
Sometimes to move forward you must first fall backwards
Quote 0 0