Rebuilt demon carb - now car won't start? But runs fine
#2046304
04/04/16 03:17 PM
04/04/16 03:17 PM
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Joined: May 2003
Posts: 561 Oakland, CA
68Bullet
OP
mopar
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OP
mopar
Joined: May 2003
Posts: 561
Oakland, CA
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After being in service for 10 years on California crappy gas, I decided to rebuild my speed demon 750 carb. I bought a basic rebuild kit (gaskets, needles, floats) and did the job methodically. Now, before I took the car apart, it was running fine, and would fire up at the first turn of the key. I put everything back together, and now it just will plain not start.
I did not change timing, and I checked that I do have spark while cranking. I can reliably get the engine to fire with starter fluid, and so I got the car running and tuned real nice. The driveability is great, idle is awesome, and I’m pulling good vacuum (indicates no major leaks). Once the car is warmed up it starts awesome. It just will not start cold. I checked the choke and it is adjusted OK. Is there something I could have screwed up during the rebuild? I am at a total loss what to check next. For the life of me I can’t figure out how I can have the carb dialed in and working awesome, yet the car won’t start when cold.
Engine combo is a 383 big block, 10:1 compression iron heads with a 230 @ .050 solid roller cam.
"Broke is temporary, cheap lasts forever"
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Re: Rebuilt demon carb - now car won't start? But runs fine
[Re: 68Bullet]
#2046429
04/04/16 05:54 PM
04/04/16 05:54 PM
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Joined: May 2003
Posts: 561 Oakland, CA
68Bullet
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mopar
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OP
mopar
Joined: May 2003
Posts: 561
Oakland, CA
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I forgot to mention that the float levels are properly adjusted. However I'll go over them once more.
I think what concerns me the most is that it doesn’t even want to try and start. Even if I pump it a few times it doesn’t even try and catch. Usually when a carb has been way out of adjustment the car will at least cough and sputter. This time there’s nothing. It acts like there’s no spark – but I’ve checked that. Then once I spray starter fluid, it fires OK and once warmed up, acts totally normal.
"Broke is temporary, cheap lasts forever"
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Re: Rebuilt demon carb - now car won't start? But runs fine
[Re: stumpy]
#2046547
04/04/16 07:57 PM
04/04/16 07:57 PM
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Joined: May 2003
Posts: 561 Oakland, CA
68Bullet
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mopar
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OP
mopar
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Posts: 561
Oakland, CA
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I’ll check the accel pump. It is working while driving, but I‘ll push the throttle and check for a strong jet of fuel. Good call, if the pump shot’s not working then there is no extra fuel when cold to start it. Which makes sense because I can pump all I want when starting and it doesn’t seem to help.
"Broke is temporary, cheap lasts forever"
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Re: Rebuilt demon carb - now car won't start? But runs fine
[Re: 68Bullet]
#2046651
04/04/16 10:13 PM
04/04/16 10:13 PM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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next time BEFORE you crank it, pull the air cleaner, open the choke & pull the throttle several times & see what you get for an AP squirt. Also when you open the throttle see where the choke stat wants to close the choke plate to
live every 24 hour block of time like it's your last day on earth
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Re: Rebuilt demon carb - now car won't start? But runs fine
[Re: RapidRobert]
#2052818
04/12/16 03:07 PM
04/12/16 03:07 PM
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Joined: May 2003
Posts: 561 Oakland, CA
68Bullet
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mopar
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OP
mopar
Joined: May 2003
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Oakland, CA
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Thanks all, it turned out to be the accelerator pump. During my rebuild I had not seated the small diaphragm 'check valve' correctly. So it required lots of pumping to build a prime and work. Somehow once the car got running it would squirt enough that I didn't notice. Anyways I took the front bowl off and got it fixed, squirts fuel like a banshee and car fires right up.
"Broke is temporary, cheap lasts forever"
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Re: Rebuilt demon carb - now car won't start? But runs fine
[Re: 68Bullet]
#2052829
04/12/16 03:18 PM
04/12/16 03:18 PM
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Joined: Jun 2004
Posts: 3,380 St. Charles, MO
wingman
Uncreative Title
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Uncreative Title
Joined: Jun 2004
Posts: 3,380
St. Charles, MO
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Glad you got it figured out. Sometimes it's the little things that drive us crazy.
1969 Dodge Coronet Super Bee 383 A4 1970 Plymouth Road Runner 440 FC7 (sold)
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