Help fixing hard start when warm

[tomfreo]

I have a '61 1600sp 6V with 28PICT carb, Pierburg fuel pump with screw inlet, and ZV/PAU 4R5 vacuum-only dizzie.

It's recently come out of storage for a year and I've been having a few problems with it.

I had problems starting the bug at first, thought it was the fuel pump, took it off, cleaned as much as I could without disassembling the two halves of the body, regreased the cavity under the pump and put it back on. Since then, I've taken it off again to check the rod wasn't binding in the phenolic (?) block. It seems to be working fine though I haven't checked the pressure.

Since starting the car I adjusted the valves, changed the oil, and did the timing (static at TDC). It starts cold fine, and runs well. Problem is starting again when warm.

I did think it was 'vapour lock' but dismissed this as the engine was not getting very warm, and pouring water on the pump didn't help.

The bug conked out on the road and I couldn't get a decent spark from the coil. I replaced the coil with a 6V coil of unknown provenance in stash (stamped Lucas 6v). This has fixed that particular problem. I'm going to order a new coil once I know what else I might want to get with the same order.

Back with the old problem of not starting when warm. The engine doesn't need to be very warm at all to to refuse to start up again. I suspect the engine's flooding. I've tried various ways to start it, (ie no throttle, half and full throttle no pumping) but it only starts after letting it sit for a while.

Moreover, when trying to start it up again, petrol drips out of the accel. pump (?) housing (see pic). This only happens in these circumstances, it appears. That is, it only appears to leak when trying to start the bug when warm.

Any ideas where I might start?
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'77 Kombi 2L dual carbs
'61 Bug 6V 1600sp

[bluebus86]

Rebuild the carb is a good place to start, you state the engine is flooding and the accelerate leaks, that is enough to require a carb rebuild. Also be sure to safety wire the carb fuel inlet, see link below my posting for info on that.

the diaphragm in the accelerator pump is failed, I would suspect other parts may be bad too. the carb air inlet looks dirty so the rest of carb might also be dirty. See that reddish or brownish color on the air inlet???

Also year old gasoline maybe bad, if in doubt about it, drain and replace the gasoline in the tank. the old gas may have gunked up the carb also

also check the float for leaks, dip it in hot water to test for bubbles from the float. you must use hot water for this test, cold water often will not show the leak, the hot water causes any gas inside the float to expand and bubble out. I heat a quart of water on the stove to boil, turn off the heat then test the float as soon as boiling stops. sink the float using a fork or other suitable tool. if no bubbles then the float is assumed good, if it does bubble it is certainly bad. remember the water MUST be hot for an effective test.
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Help Prevent VW Engine Fires, see this link.....Engine safety wire information

Stop introducing dirt into your oil when adjusting valves ... https://www.thesamba.com/vw/forum/viewtopic.php?t=683022

[mukluk]

Only thing that really jumps out at me is the timing you're using for that distributor. Per the info at the Old Volks Home, the ZV/PAU 4R5 advance is 10° at 1.3"Hg and 15-21° at 2.8"Hg... when timed at TDC, your overall advance is at most 21°. Have you checked to see what overall advance you're getting? A change to 10° BTDC may be in order.
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1960 Ragtop w/Semaphores "Inga"

[tomfreo]

Thanks for the heads up - I've been timing the engine at the second of two close notches in the pulley which I'm sure is 10*BTDC. But I've also been using the same notch to line up TDC for the valves. Have to go back and get that sorted!

I'm not entirely sure the engine is flooding. How would I tell fro sure? I'm thinking it might just be weak ignition system.

Would a failed accel pump diaphragm give me the symptoms described? The car runs fine when it starts, good smooth acceleration. I never get it up above 45-50mph though (have to look into getting the front wheels balanced!)

The tank is full of fresh gas.

I'm going to bite the bullet and have a go at rebuilding the carb. I'm having trouble finding a rebuild kit in it with anything more than just the gaskets though.

With the symptoms described (hard start when warm) what things in particular should I be paying attention to when it comes to rebuilding the carb?
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'77 Kombi 2L dual carbs
'61 Bug 6V 1600sp

[Bret2094]

The hard start when warm thing screams old coil to me...my first experience with vw's was my grandfather's 67 with the original coil..back in 2010. It would crank fine till it got warm in the engine bay and then nada. Lol before i figured out what it was, I drove it several times to school, and on a warm day it would go 8.5 miles down the road which was a half a mile short of the school parking lot.( lots of oh shit lets coast the rest of the way and hope no one pulls out in front type moments) Anywho, Ive since had 2 separate cars with similar warm start problems. Try a new coil out and see if it fixes some of your problems. Rebuilding the carb wont hurt either, but id check the coil first


Bret

Edit: I realize you changed the old one out, but using one that is going bad but still semi functional could cause you reoccurring problems
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1959 baja beetle ragtop( going back to Full body)
1959 beetle
1960 Beetle frame Custom buggy
1962 Karmann Ghia
1967 beetle( august 66, first car)
1967 beetle (parts car)

1977 Westfalia Camper

1972 Plymouth Duster

Just another 22 year old jackass who caught the bug, and lives by the motto " NO fatchicks allowed" , I've got too many cars as is (buses N/A)

[andk5591]

I had the warm start issue with my 65 and swapped the coil and it corrected it. Would suggest a general tune up though. Condensor, points, etc. Any of which could give you weak spark. Also make sure your power conection to the coil is good. The connectors in the engine compartment can get really cruddy.
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D-Dubya Manx clone - 63 Short pan,1914.
Rosie 65 bug - My mostly stock daily driver.
Woodie 69 VW woodie (Hot VWs 7/12).
"John's car" 64 VW woodie - The first ever
Maxine 61 Cal-look bug - Cindy's daily driver.
Max - 73 standard Beetle hearse project - For sale
66 bug project - Real patina & Suby conversion
There's more, but not keeping them...

[Harris]

As noted from a previous post on hot or warm start.

With a properly done carb, timing set correctly, no vacuum leaks from carb to manifold and manifold to heads and a good coil, your ready for the warm or hot hard start. To keep from flooding with the 28 pict slowly press the accelelator down to keep that squirt of gas from the pump out of the throat of the carb. Hold it there until you get a fire up and it starts to smooth out. DON'T Puimp the accelelator. Also check that the choke is standing completely upright. The 28 PICT with the ceramic first generation choke takes a while to open, but seems, at least with me, to close down quickly The engine does not need the additional gas to fire up. I keep a short spring to hold the choke open if I need it. This works for me and helps keep my sanity.

[Harleyelf]

Your first step is to isolate the issue. If the spark goes away when warm, no amount of carburetor tweaking or starting fluid will make it run.

Coil, condenser, points wire are the most likely suspects. Try hot-wiring the coil's power lead when it happens next. If that makes it start, the issue is in the ignition switch and/or the wires from it to the coil.

If the starting fluid makes it catch for a few moments, check the fuel shut-off solenoid. Does the choke actuate properly? The stepped idle cam that the throttle arm hits should move up to the lowest step after ten minutes of running.

You say 1600 single port like you think that was the stock motor. Someone has worked on it since it began life as a 1200. Perhaps the carburetor is too small to feed the extra displacement. At the very least, take the screws off of the accelerator pump cover plate and look for obstructions and a torn diaphragm. Dripping fuel is a fire hazard.

[jzjames]

The problem could be with the starter motor rather than fuel/electrical. After the engine is warmed up and hot, the anemic aftermarket starters don't seem to have the torque to turn the engine very well.