TheSamba.com :: View topic - Engine wants to quit/stall

Thu Feb 19, 2004 1:26 pm

This is starting to aggrivate me, and I haven't been able to find similar posts, so here goes: I've got a 73 Thing, totally stock. The engine is a fresh 1600 - rebuilt less than 1,000 miles ago with new distributor, new 34 Pict 3 carb, etc. She ran great all summer long - would start up right away and just needed about a minute or so to warm up and hold a steady idle.

She was garaged for about 3 months without being started or run at all, and the next time I started her up, my idling/stalling problems began - here's what it's doing:

Engine starts up just fine - turns over quickly and easily, and there's no unusual noise - as long as I keep feathering the gas (pumping the pedal lightly), she'll rev up and down accordingly and keep running. The problems begin when I do either of the following:

a) If I take my foot off the gas and let her settle into an idle, she just sputters and stalls within a few seconds.

b) If I hold my foot STEADY on the gas at ANY rpm, she runs steady for a couple of seconds, then starts to sputter and will stall unless I start feathering the gas up and down again.

To me, when it begins to stall, it almost feels like it's starving for gas. While starving for gas and flooding feel pretty much the same going into a stall, I think I can rule out flooding, since after it stalls, it starts up again quickly and easily (not at all like a flooded carb).

All of the fuel lines from the tank to the carb are new (less than a year old). The in-line fuel filter is also brand new. I replaced it yesterday, and on inspection, the old one didn't look bad at all. Looking into the carb, things seem pretty clean (it's still looks new). All of my electrical connections are tight and clean, and my generator light does not come on until after she dies. Spark plugs, rotor, points, etc., are all pretty fresh. The fuel tank is original - I just filled it up with premium and added a bottle of sta-bil. Can't rule out gunk in there, but like I said, the old in-line fuel filter looked pretty clean. Coil is not new, but I don't seem to be getting any kind of generator lights etc., and she'll keep running as long as I baby the gas.

Any ideas??? Many thanks in advance!!!

Thu Feb 19, 2004 2:08 pm

make sure the wire is plugged onto the electromagnetic idle solenoid/cutoff valve.. and that it has power...
(it is on the left side of the 34 carb.... ) turn the key on and pull the wire off and touch it back... it should make a click sound.

also make sure the soleniod is tight in the carb body

or you may have a piece of trash in the "idle pilot jet" ( right side of carb)

I found plenty of threads using the search!! :D :wink: heres one...

http://www.thesamba.com/vw/forum/viewtopic.php?t=52996&highlight=idle+pilot+jet

Thu Feb 19, 2004 3:15 pm

Thanks, I'll give that a shot. The connection to the solenoid was definitely good, and it seemed very secure when I checked it last night, but I didn't do the ignition, on click test (didn't really think to test it, since it's fairly new). Will keep you posted.

Do I need to dissassemble the carb to get at the idle pilot jet for inspection and cleaning, or can I inspect and clean it in place on the manifold?

Thanks again.

Thu Feb 19, 2004 5:38 pm

hey i had the same problem with my bus i dono if its the same im only 16 but what i did was take off the carbs and make sure every thing was clean and there was a clog i cleared that then ... make sure ur idle speed and every thing is correct like ur timing idle mixture screw and all that then drive it

Thu Feb 19, 2004 7:41 pm

What kind of distributor ?

Fri Feb 20, 2004 4:54 am

I agree with keithernet - sounds very much like the idle circuit - probably the cut off solenoid - check it 'clicks' when you turn the ignition on and off - better still unscrew it get a peice of wire connected to it, earth the body of it on the neg terminal of your battery and use the wire on the posotive side to switch it from the pos side of the battery (make sure theres no fuel around anywhere). Through the holes in the end of the valve you should see a needle go in and out - sometimes these stick because of fuel deposits - you might be able to clean it up with some carb cleaner if it is sticking.

Another thing to check is there should be a rubber o ring / seal on it, if this is missing or if the thread is damaged then the valve can screw in too far and this sometimes restricts the fuel flow - to check this simply unscrew the solenoid out by about half a turn and see if the situation improves.

If all this is ok then either you have a blocked idle jet circuit (try soaking in som carb cleaner and then blowing through with an airline), or possibly the carb simply isnt set up correctly.

The idle valve is the one controlled by the knurled wheel / adjuster on the side of the base of the carb, its simply a needle valve that restricts fuel at idle. To set this up wind it out a few turns then get the engine running, then slowly wind it in until the engine starts to die, at this point back off 1/4 of a turn or until the idle smooths out, the idle valve only affects the fuelling at idle, and not at higher engine speeds, this is taken care of by the main jet.

I presume you got a single carb, if you got duals the same applies but getting the idle mixture set takes a little bit of experience as only 2 cylinders will die when you wind it in, you just need to get used to the different sounds as the engine wont completely die.

Hope this helps.

PS - if the solenoid is shot and doesnt operate there is a quick fix - basically cut off the end part and then screw t back in - you will suffer from overrun after you shut the engine off but if youre stuck it's a kind of 'get you home' type of fix.

Fri Feb 27, 2004 12:48 pm

I'm still having troubles here, but thought I'd post an update: I tried all of the kind advice suggested, but still can't get her to run without stalling.

The carb has less than 5oo miles on it, but I still took it apart, cleaned it and tested it's electrical components anyway. No problems with anything there, and it was super clean when I took it apart. Still, I cleaned it out and gave it a good blast with compressed air before reassembling and reinstalling on the manifold.

I unscrewed the sending unit assembly from my gas tank, and took a good look inside. There's some crud in there for sure, so I siphoned about 5 gallons out, and ran a fuel line directly from the spare gas can to the fuel pump (thereby eliminating the tank or fuel lines as a possible source of the problem). Didn't run any differently this way, so I can safely say that the tank, fuel lines and carb are not the source of the problem.

I'm still concerned about fuel delivery, though, and noticed that when it was running, there was just a little bit of fuel visible in the clear in-line fuel filter that I have installed in my engine compartment. Anyone else use one of these? How much fuel do you normally see in it when you've got the engine running? It's brand new, BTW - was teh first thing I replaced when this problem started.

Something else to consider - This is an old-school, stock 1600 setup I'm running here, and I use a 009 distributor. It's also very fresh, and it (and the points, cap, rotor, spark plug cables and spark plugs) have less than 500 miles on them. On visial inspection, I saw very little carbon buildup - just what looked like normal wear. Still, I know that keeping these 009's adjusted can be a real bitch. Any advice on how to do it properly? Any good websites on it?

Thanks again!

Fri Feb 27, 2004 7:00 pm

Yeah, this one!

http://www.thesamba.com/vw/forum/search.php

go here and type in 009, narrow the search to one forum at a time... beetle, perfomance, super... you'll get tons of hits...

how to time an 009 is one of the 10 most answered questions on this site :roll:

Fri Feb 27, 2004 7:18 pm

chinarider wrote:
I'm still having troubles here,
[

The later 34 Pict 3 cars use an air bypass for idle speed. Most of these carbs were installed with vacuum distributors that had a retard feature 5*ATDC.
The air bypass circuit needs lots of airflow to counteract that retarded timing, which is exactly what it was designed to do. Lots of airflow and retarded timing gave the factory engineers a hot clean idle. An 009, on the other hand, has it's idle timing ( after you do the dynamic at 28* BTDC at 2,800 rpm for example) way too advanced for the air bypass circuit. You would have an idle up at 1,500 to 1,800. So, most people crank the air screw down to almost closed to get the 900 idle, and presto! no more idle circuit.
Colin