1973 Super Beetle

[glennj3cub]

I’m still having problems after replacing essentially everything to rebuild her mechanically.
# 1, if it sets up a week or so I usually need to pour gas into the carburetor, then it fires up.
#2, when it does run it runs irregular, like sputtering. It does run after a few minutes and won’t cut off spontaneously.
It does choke down when I begin driving if I don’t keep the engine at higher RPM.
If I put it in 2nd gear at lower RPM it does not like to go.
This has been going on for a while now.
My only option seems to begin replacing ignition items again or double check the ignition timing again. I’m really not sure I ever got it right.
Good advice needed!
Thanks

[VW_Jimbo]

Sounds like a weak ignition system, low battery voltage, low compression, poor gas quality or a vacuum leak.

I would start at the beginning. It is how I have diagnosed cars for 32 years. If your in, adjust those valves again first thing in the morning, then run a compression check. Remove all the spark plugs. Be sure to crack the throttle plate to WOT, before testing. Remove the coil power feeder wire (black wire connected to the 15 side of the coil). Don’t worry about the engine being warmed up. I know off the numbers if they are good or bad. Seen a couple Bugs in my time!

Change the oil, while you are at it.

Post those up and anything out of the norm you encounter during that regiment.
_________________
Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!

[virusdoc]

I can't tell from the most recent engine compartment photo in your gallery--do you have the manifold pre-heat installed? And it appears you put on a new muffler during your rebuild--did you verify the manifold preheat tubes are open, and that both sides of the new muffler are actually drilled open to allow exhaust to pass freely through the preheat risers?
_________________
1976 Convertible Super Beetle, "June Bug".
FI-->34PICT3 carb conversion-->now dual 40 IDFs
Self-rebuilt 1904 (after totally botching a 1641 rebuild, cussing a lot, and throwing lots of cash in the fire)

[glennj3cub]

Thanks,
This car sits under a shed and I don’t typically drive it except around the farm to warm it up. Because I don’t have insurance on it.
I did adjust the valves & I prefer not to do that again anytime soon.
I’m not sure what the preheat risers are or what your asking regarding drilling a pre heater vent through the new muffler? The heater valves do work. I’m missing a hose from the right bottom rear that connects to the air filter vent. I think that’s to help warm up the carburetor.

[virusdoc]

In this photo from your gallery, the manifold preheat risers are the pitted old pipes coming down from under the fuel manifold/carburetor and attaching to your new muffler. These pipes are critical for proper engine function because they use exhaust heat to vaporize the fuel as it travels from your throttle to the intake valves. Yours looks like the original, and these generally get plugged up with carbon over the years. In addition, many after market mufflers don't have holes where the heat risers attach, and need to be drilled out (even those with flanges for attaching them like yours has).

If either of these is the case, you'll never get a center-mounted carb to run well on that car.

_________________
1976 Convertible Super Beetle, "June Bug".
FI-->34PICT3 carb conversion-->now dual 40 IDFs
Self-rebuilt 1904 (after totally botching a 1641 rebuild, cussing a lot, and throwing lots of cash in the fire)

[VW_Jimbo]

[glennj3cub]

Makes sense. The problem does not go away after driving 10 to 15 minutes. I have a fuel pressure regulator connected to 5 lbs I believe. Maybe I should increase it?

[stagewex]

New to old bugs but not air-cooled carbie engines (BMW bikes & Ural sidecar rigs).
It sounds like a fuel issue to me. Starvation as mentioned coupled with debris settling in your carb.

You have the same year (1973) SB as I so almost 49 years old. Have you had your tank cleaned/flushed yet?

[glennj3cub]

I’ve replaced almost all mechanical items including the gas tank & all lines, eventually replaced the carburetor too, with the pressure regulator.

[Matt Wilson]

Looking in your gallery - the carburetor float retaining plastic clip is installed backwards, which could cause some float/fuel disruption. (Maybe solved in another thread already?) Also, buy some vinyl vacuum caps and throw away pieces of hose plugged with rusty screws. Vacuum line on the carb should be 3.5-4mm ID hose. The smallest fuel hose in that construction is 3/16" [4.76mm], which is larger than required and may create a leaking issue.

Maybe there's an optical illusion in the photo, but the distributor doesn't look clocked right, making the timing not right. Be sure NOT to time that distributor/electronic ignition with static method, use timing light.

Make sure all plug wires are seated and double/triple check they are in the correct order. Do the pencil trick in #1 spark plug hole if you have to prove to yourself that TDC mark on the crank pulley and on the distributor rim all work with how you have the plug wires installed.

Don't fret about adjusting the valves, since you should probably do it every oil change. You'll get good/fast at checking and making any adjustments as needed.

Once you've done all this stuff, you need the correct tuning instructions for the specific carburetor that you have. Be sure the idle cutoff solenoid is working and *clicks* when you turn the key. Faulty solenoids are often chopped off in a roadside repair situation and don't help the engine run right.

Ensure the fuel tank is vented so that air can go in and out properly.
_________________
1972 Standard Beetle
1969 Baja Beetle

[VW_Jimbo]

[VW_Jimbo]

[glennj3cub]

You may be looking at the original carburetor, I put a new one on it. Pressure regulator is on 2 (I previously said 5).
I just cranked her up, warmed up. She she skips in static run up, just doesn’t sound good.
I’m rechecking the timing with a light. Amazingly I can’t even see the marks I used several months ago. It is clockwise about 3 pm while running. I have the distributor marked for alignment.
I may have to pull the # 1 plug and turn to TDC then look at the rotor.
Verify for me # 1 is the right rear looking at the engine from the back.
The pully has one notch but I have 3 spaces painted and I don’t remember why.

[VW_Jimbo]

Yes! #1 is the rear right side spot. It is embossed on the cooling tins, if you can see it. Like this one.

Why do you have a fuel pressure regulator on a stock set up? Get rid of that variable. Straight fuel pump feed to the carburetor. That has been the norm for well over 80 years.

You stated changing out the gas lines. That included the filter? Got a picture? Was the filter direction specific or a generic one?

Once you get it warmed up and it skips......can you recreate that at will? If so, what happens if you squirt a shot of carb cleaner in at the same anticipated moment? Does it bog down or pick up in rpms?
_________________
Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!

[glennj3cub]

New tank & lines, filters. I initially put an electric fuel pump on it thus the regulator.
Spraying carb cleaner into it should make it lug down
By the way the risers do warm up on static running for 10 minutes but I could hold them with my hands.

[Matt Wilson]

My point is to know you have the foundation stuff dead on (valves and ignition). If there's question, just quickly check those boxes, then start messing with carburetor.
_________________
1972 Standard Beetle
1969 Baja Beetle