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davidw99
Samba Member
Joined: September 04, 2003
Posts: 696
Location: Boston, MA
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 Posted: Wed Nov 27, 2019 7:07 am Post subject: Re: Hard to start when hot |
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I had this problem a while ago. Coil was on the way out. I didn't realize that was the problem until it quit completely.
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Dave
'73 Saturn Yellow Sports Bug that has undergone a full pan off restoration. "Herbert IV."
'67 Sedan. "Bellamy." Currently being "refreshed" and recently repainted.
Last edited by davidw99 on Thu Nov 28, 2019 4:57 am; edited 1 time in total |
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Tom K.
Samba Member
Joined: March 10, 2005
Posts: 1605
Location: Central Pennsylvania
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| Posted: Wed Nov 27, 2019 11:57 am Post subject: Re: Hard to start when hot |
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| ashman40 wrote: |
| I would expect that if you left your car to sit for 45min with the ignition OFF the choke coil will have cooled a bit and may have even closed down some by the time you get back to start driving. |
I've often wondered about this. How did VW justify this system? Is the choke spring designed to cool at the same rate as the jugs, pustons, and heads? Because the choke seems to close before the engine cools, you can imagine how easy it would be to flood the engine. I too use no foot action when starting a warm VW, and it works for me.
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'91 Vanagon Westfalia
'70 Beetle Convertible
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'65 Ghia: https://www.thesamba.com/vw/forum/viewtopic.php?t=762478&highlight= |
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ashman40
Samba Member
Joined: February 16, 2007
Posts: 15985
Location: North Florida, USA
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| Posted: Wed Nov 27, 2019 12:09 pm Post subject: Re: Hard to start when hot |
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A good working choke will only remain ON for 5-10min when adjusted properly. Once you turn the ignition ON it begins to warm up. Once the coil is HOT, it should release the choke to OPEN by the weight of the fast idle cam.
If you park your car for a little while and allow the choke coil to cool a bit, when you jump back in it should only remain ON for even less time since the coil will still be warm.
While the choke is ON (fully closed or partially closed), the 3-screw diaphragm on the rear face of the carb (near the choke coil) will force the choke butterrly OPEN when the speed of the air down the carb increases (higher rpms). This prevents the choke from blocking air flow as the rpms increase. You can see this if you remove your air cleaner and look at the choke butterfly while you rev the engine. You should see the butterfly OPEN when you pull the throttle arm and close back down once the rpms drop back to idle.
So once your are driving down the road the choke is mostly disabled. Even more so if the choke coil is already warmed up some.
The choke coil is not so much a temp sensor as a temperature based "timer". You adjust the choke at different times throughout the year so that the choke will remain ON for 5-10, first thing in the morning. Just so your engine doesn't die when you come to a stop light. Once the time has passed (coil is HOT) the choke is disabled (OFF).
When I compare modern FI computers that monitor the air temp and enrichen the mixture and add air into the flow to increase the warm up rpms and mixture... it does make the Solex carb seem like 'steam punk" technology. But these carbs provided reliable (if not efficient) service for decades of cars! Compared to race carbs that don't have a choke at all, the Solex is a "luxury carb" 
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AshMan40
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'67 Beetle #1 {project car that never made it to the road  }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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