Won't Idle 74 bus with Dual Webers

[brokengun]

I've been trying to get this 2 liter type 4 engine to idle. It came with dual webber carbs and I don't know a whole lot about its history. Previous owner claimed it used to run and now has a fuel delivery issue. After cleaning the carbs I am able to get the engine to run (pretty rough) but it will only stay running while pumping the gas pedal. I verified fuel is getting to the cards but the engine won't idle. Before cleaning, the accelerator pump on one wasn't working very well but now both seem to work fine.

The engine will only continue to run while I pump the gas pedal. It will also occasionally backfire.
Not sure where to go from here. We've checked the points. Should I try to adjust the valves/timing? I know syncing the carbs can be an issue but first I need to get the engine to idle. Suggestions?
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1984 Vanagon Adventurewagen with EJ22 conversion
1975 Beetle - Big whole in the floorboards
1974 Westy - Will be on the road one day!
1973 Bus - sold

[old DKP driver]

A common mistake is having to back track into the basics that should always
come first.

DWELL comes before Timing and Valve adjusting comes before Dwell period !

What fuel pump do you have? and what pressure do you have.
how clean is the gas tank and fuel filtering?

Idle circuits on 40 IDF carbs are simple and occasionally need the orifices
blown out with compressed air

Do you have A UNISYN OR SNAIL gauge to balance the carbs and get the idle set @approx.: 900 rpm's

You really need to know these carbs to keep from spending unneeded amounts of $$
www.aircooled.net has good info but, having a weber manual may help too.
_________________
V.W.owner since 1967

[Desertbusman]

There are a few different Webers. Which do you have?
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71 Superbug
71 Westy

[busdaddy]

[rustybusjef]

try this
http://www.webercarbsdirect.com/v/vspfiles/images/Weber%20Trouble%20Shooting%20Guide.pdf

[Desertbusman]

Hey guys, do you ever get the feeling that you're talking to a blank wall?
_________________
71 Superbug
71 Westy

[brokengun]

Sorry for the absence, but I've got Weber 34 ICTs.

Thanks for the weber carb troubleshooting guide. I've disconnected each fuel line at the carbs and verified that the fuel pump is reaching the carbs. I emptied the fuel into a paper cup but I don't have a good intuition for what the fuel pressure is or should be. Maybe I this is worth buying a fuel pressure gauge to test?

I'm not convinced a balance tube is installed. I'm away from my bus now but I'll try to verify it has one and it is installed properly.

We put some new gas in the tank too and have been spraying starting fluid down the carbs but I think it's more of a problem idling instead of starting.

Should I buy a synchronizing tool and/or a fuel pressure gauge?
_________________
1984 Vanagon Adventurewagen with EJ22 conversion
1975 Beetle - Big whole in the floorboards
1974 Westy - Will be on the road one day!
1973 Bus - sold

[RCK445]

Have you double checked that you do not have any vacuum leaks. I recently had that problem, a vacuum hose got disconnected while cleaning and I was unaware that it happened. Bus cranked and would rev but no idle. plugged it back and she magically idled. Also check the fitting that comes out of the bottom of the gas tank. Unscrew it and there is a very fine mesh fuel filter that can become clogged. It may not come out initially gently push up on the silver collar and it will come free of the tank.

[brokengun]

After some more fiddling I did a fuel pressure check and that seemed to be fine (3-3.5 psi). I cleaned the idle jets and re-adjusted the idle mixture adjustment screws but to no avail.

The engine will run if I pump the gas but just doesn't idle. My next move is to take off the carbs and soak the bodies in carb cleaner to try to be sure the idle circuits aren't clogged in some way. I noticed a gasket one of of the carbs was missing so I'll be replacing that too. I'll keep you all posted with my results.
_________________
1984 Vanagon Adventurewagen with EJ22 conversion
1975 Beetle - Big whole in the floorboards
1974 Westy - Will be on the road one day!
1973 Bus - sold

[babysnakes]

You have a power booster on your brakes that works off vacuum from your carbs. Find the hose nearest the carbs, disconnect and plug. Is there a difference? In that line there is a check valve, they don't go bad often but do sometimes.

[Desertbusman]

After you do that then do---

Go to CB Performance and get the instructions for the 34 ICT's. Two important parts to it. THe setup and then the tune. Do the setup first. Baby Webers can idle great.
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71 Superbug
71 Westy

[mnskmobi]

[Desertbusman]

[brokengun]

Alright, so here is the latest. I removed both carbs, disassembled them and cleaned them in GUNK parts cleaner with a dip tank. Let it sit about a couple of hours. Re assembled the carbs and installed them.

The balance tube is installed and free of debris and kinks.

The engine still will not idle unless I back out the idle jet screw and allow fuel to bypass that jet. The idle jets appear clear and i can run a piece of wire through all the holes in it. However, I did notice the the jets that are installed in it are one piece and not three as shown in the exploded diagram I've seen (http://www.carburetion.com/diags/34ictpic.jpg). Parts 19,20 and 21 make up the idle jet but mine seem to be a single piece with a rubber O-ring.

At this point I am unsure if the problem is with the idle circuit within the carb body or with the idle jet itself. Where should I go from here? Remove them again and clean or try different idle jets? As soon as we screw in the idle jets the engine starts to die.

With the idle jets backed out the engine runs great though and I was able to drive it around the yard under it's own power for the first time!
_________________
1984 Vanagon Adventurewagen with EJ22 conversion
1975 Beetle - Big whole in the floorboards
1974 Westy - Will be on the road one day!
1973 Bus - sold

[brokengun]

After disassembling the carbs again and reviewing the exploded diagram we realized that did not remove one piece, the emulsion tube. Pictured here as #40 http://www.carburetion.com/diags/34ICTdiaginfo.asp The tube looks like the seat for the air corrector jet (41) however it comes out if you turn the body upside down and smack it on a solid flat surface (being careful of course). It was filled with some crap in it, so hopefully after a second more through soaking that will solve our problem.
_________________
1984 Vanagon Adventurewagen with EJ22 conversion
1975 Beetle - Big whole in the floorboards
1974 Westy - Will be on the road one day!
1973 Bus - sold

[brokengun]

So, I'm still at a bit of a standstill on getting these carbs to idle. I disassembled them again and say a small trace of debris in the filter. I was trying to follow the guide for setup and adjustment (http://www.redlineweber.com/html/Tech/34_ICT_tunning.htm) but the engine simply will not idle.

On the advice of a local VW guy, I turned the idle jet back (allowing fuel to bypass the idle circuit) and I can get the engine to stay running with one of the idle jets cracked open about a quarter turn. Here is the kicker though, if both idle jets are seated properly it won't idle however if EITHER one of the idle jets is open a tiny bit the engine will run. I was hoping to narrow the problem down to one carb or the other but it seems like there could be something else at play?

Where do you all think I should go from here? Maybe I should be on the hunt for some vacuum leaks.

Also, I noticed that there is a threaded hole with a screw that is perpendicular tot he hole where the idle jet is installed. I have no idea what it is for or even why it is there (for both carbs) it doesn't seem to be pictured in any diagrams I've seen so far. Any ideas what it might be?
_________________
1984 Vanagon Adventurewagen with EJ22 conversion
1975 Beetle - Big whole in the floorboards
1974 Westy - Will be on the road one day!
1973 Bus - sold

[timvw7476]

Make sure the vacuum ports from each intake manifold are plugged or properly connected to the power brake vacuum collector pipe, 34 ict Webers
really have just two screws to control idle, they are on the mounting flange
of each carb and you can see the spring behind each one. The throttle plate
screws are there to adjust each throttle plate to an opening of .004", this
is the only time you touch them, after that the idle adjusting is done with the idle mixture screws, turn them both in gently, then out 2 1/2 turns as a
starting point. If your throttle blades are open greater than .004",you are
trying to run on the main venturi/accelerator pump circuits and not the idle
drillings Weber intended. The large screw you write of is a brass jet holder,
and if you achieve some type of idle by opening it a bit, you are feeding a
vacuum leak unmetered fuel. Hope this info helps!

[Tcash]

Cap one carb, hook up smoker to one carb and smoke away. Good Luck
Smoke Tester/veloandy