The first 1/8" of throttle

[Mal evolent]

long term problem that led to this: spark plugs foul within 25 miles. vast black clouds when you open the throttle. tried fussing with the jets to reduce this richness. stepped down to 117.5, from 127.5. no more vast black clouds. acquired and installed an Innovate 3844 MTX-L air fuel ratio meter. it says I have 12.5: AFR @ about 1/4 throttle and higher.

but it stops stone cold dead when I take my foot off the gas. If I take the throttle return spring off I can ease the throttle down to 1/8" off the cam plate and it runs fine. shut the throttle one tiny bit from 1/8" and it drops stops stone cold dead. no amount of diddledickery with the mixture screws changes anything. changing idle jet does not cure the problem.

spark plug tester shows big 3/8" arc, at least 20 KV, every time. static timed to 7.5 BTDC

the AFR goes up to 22.something when you close the throttle. so it's running lean - running out of gas, apparently - that last 1/8"

what should I be fiddling with to get that last 1/8" to work and put get to put my return spring back on?
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73 Beetle Baja, Ghia front brakes, Type 3 rear brakes, 2220 ( 94 X 80 ), Weber Progressive, Bosch SVDA, '97 Mustang seats

Baja Bugs for Volkswagen Virgins: Index

[modok]

The carb is clearly not feeding enough fuel at that throttle setting. You need to look at the idle and transfer circuits of the carb and find the problem.

Could also be a vac leak too.

[andk5591]

Suggestion - include carb and other numbers in the post itself - didnt notice that in your signature initially - Would blow out your idle circuit passageways real well. Dont remember if there are any check balls in the idle circuit or not on a 34, but if there are, one sticking would do it as well.

Little bit of reading on a 34

http://www.thesamba.com/vw/forum/viewtopic.php?t=56411
_________________
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...

[modok]

one with a fast idle cam, so probably a factory solex of some form

[SRP1]

Idle fuel cut off solenoid not working or no power to it.
Also the 34pict3's idle is adjusted with the air bypass screw, not the stop screw and cam, that's for the cold fast idle setting.
What camshaft in this engine??

[andk5591]

I thought the cutoff killed all fuel flow or does it just impact the idle circuit. Just curious.
_________________
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...

[SRP1]

[Mal evolent]

car worked until I fixed it. carb is new, has less than a tank of gas run through it. cutoff solenoid clunks and bangs when you disconnect or reconnect it.

it has to be something I changed while making things better. I really don't want to go back to the 127.5 main jet and start all over.
_________________
73 Beetle Baja, Ghia front brakes, Type 3 rear brakes, 2220 ( 94 X 80 ), Weber Progressive, Bosch SVDA, '97 Mustang seats

Baja Bugs for Volkswagen Virgins: Index

[SRP1]

[youngnstudly]

I found several issues with one of those new stock Brosol 34 pict-3 carbs over 10 years ago, and I don't imagine the issues have improved any since that time! Dirt in float bowl and passages, and a tight fitting choke shaft were the 2 biggest issues I found, and the needle and seat ended up sticking after dirt found it's way inside. I had to manually step the fast idle cam mechanism down after warm up or the choke would stay on all the time too.

My neighbor (mentor) suggested that I take the carb apart and fix the issues or I'd be taking a chance with a potential engine fire. Once I did that, things were fine. The mechanic who sold me the carb mentioned (afterwards, of course) that he had occasional problems with them and would often check them over for loose screws and dirt in the passages.

Point is, assume nothing about your "new" carb. I used to think that new meant "just bolt it on and go", but I quickly learned otherwise, after a few setbacks in my teen years. Check everything twice if need be!

Also make sure you have vacuum lines hooked up correctly. Another lesson I learned the hard way by mixing up vacuum ports!
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The economy is in a state of disaster, we have NO time for common sense!

[andk5591]

Is there a quick and dirty for testing without the idle cutoff valve - may be a good idea for the OP. As in can you just remove it and jam in a vac cap for a quick test?
_________________
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...