71 Super Beetle losing power and won't start when warm

[aRabidGerbil]

I've got a 71 Super Beetle that's having problems when it's warm, either from driving, or just a hot day. If it's hot it takes a few goes to start and sometimes just won't start, I get starter noise and nothing else. If it's running it idles smoothly and runs fine at speed, but if I'm trying to start from a stop, I need to slowly coax the RPMs up, because it will immediately die if I just give it gas.

What I've tried so far:
-Checked the coil, got a weak spark so I replaced it, problem still there
-adjusted all valves to make sure none of them were stuck closed
-sprayed propane around the intake manifold and carburetor looking for a vacuum leak, didn't see any change
-tested pulling spark plug wires to make sure each cylinder was firing, all were

Does anyone have any idea where to look next?

[VW_Jimbo]

Like your handle! Are you a friend to Richard Gere?

What is your choke doing?

What is the spark output WHILE cranking the starter? This could be a voltage problem. Check your resting battery voltage first thing in the morning. Write it down. Then crank the engine. What is the voltage while cranking?

What ignition system are you running?

Engine compression with a warm motor is?

Got a picture of your engine?
_________________
Jimbo

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

[bsairhead]

Could be choke, or timing.

[aRabidGerbil]

Sorry for the late reply, I needed to wait a bit to get someone to crank the car for me.

Choke is adjusted when cold and is opening when it warms up

Coil is giving a strong spark when cranking, voltage on the battery drops to around 10-11 volts

I've got an electronic ignition, so no points to worry about

Unfortunately, I don't currently have a compression testing kit, I'm waiting to borrow one from a friend

Picture of engine

[sb001]

Normal in warm/ hot weather.
WAAAYY fewer owners DON'T have this problem, than those that do.
_________________
I'm the humblest guy on this board.

1969 autostick sedan, family owned since new
1600 SP engine
Solex 30 PICT 3 carburetor
Bosch 113905205AE autostick distributor

[baldessariclan]

Owner’s manual procedure for starting an engine at “operating temperature” (i.e. hot) is to hold the accelerator all the way to the floor while cranking (ref. below) — quite a bit different than when starting the engine cold or merely “warm”:

Definitely don’t pump the accelerator or otherwise flood the engine when hot, or yes will be much harder to start. Slowly depressing and holding the accelerator all the way to the floor prior to or during cranking always seems to work for me when my engine is really hot.


The 34 PICT-3 carb and 009 distributor combination (which looks like is what you have in your engine pic) is well known to often cause flat spots and stumbling on initial acceleration. However, sounds like you have a bit more than just that going on. Perhaps a bit of poor tuning, and/or malfunctioning distributor advance? Or alternately your carb’s accelerator pump not working, or other partial fuel starvation issue? Just a couple ideas to think about…
_________________
1971 Standard Beetle — fairly stock / driver

baldessariclan -- often in error, never in doubt...

[jinx758]

Also ...

*accelerator pump squirt
*fuel cutoff solenoid
*gas tank not venting
*vapor lock from fuel line/hose touching a hot item

Ideas that mite stick to a wall ... stay safe

jinx
_________________
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It's not unlike the same difference

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My Craigslist rescued 100 footer :
1971 Standard Bug
1776cc dual port
034 distributor
38mm EGAS Carburetor