Idle -> WOT: hesitates and chokes, then revs... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**COBALT** · 04-12-2002, 03:01 PM

I actually haven't gotten around to rebuilding my little Rochester 2G carb (bad boy), so I'm being lazy right now.

Why is my carb. hesitating (badly), then causing this loud choke-sputter noise, and finally revs up when put full throttle from idle (idle to WOT)? Is it the metering of fuel from the bowl? The float? Or maybe those little bleed channels are plugged up that allow idle air? The throttle need adjusting?

This may be a good learning experience for me. Anyone know what it is right off the top of their head?

------------------
'69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed!
'69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast).
Seattle, WA.

*See pics of my trucks and project at www.webshots.com!

Gordo · 04-12-2002, 03:22 PM

Take a look down the throats of the carb, (engine off) and operate linkage from idle to WOT,,you should see two nice squirts of fuel as you do this,,if not your acelerator pump has had it,, time for rebuild. Other possiblities,,vaccum advance and timing.

------------------
1971 C10 swb stepside 350/700R4/3.73posi
Killingworth, Connecticut

**COBALT** · 04-27-2002, 05:07 PM

Well, I did what Gordo suggested and I think he's right. From idle to WOT with engine off I'm barely getting fuel out of either jet. Mainly just dribbles.

After a couple of times I can sometimes get a definite jet out of the passenger side, but not the driver's side ever.

What next? Accel pump? I assume I'm going to have to look for some hard parts somewhere...

------------------
'69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed!
'69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast).
Seattle, WA.

*See pics of my trucks and project at www.webshots.com!

Benrs86 · 04-27-2002, 05:14 PM

yeah, you should get a nice hard squirt of fuel. get a accellarator pump but if i were you while i had it all apart, soak it good in carb cleaner(not the spray kind) and do a little rebuild. good luck, Ben

**COBALT** · 04-27-2002, 08:24 PM

I have the rebuild kit (which includes all the little gaskets and crap), and a huge can of carb cleaner. I was going to take all the hard parts and just let them soak over night.

I wonder if I can even get accelerator pump parts for the carb through NAPA???

------------------
'69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed!
'69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast).
Seattle, WA.

*See pics of my trucks and project at www.webshots.com!

71402BB · 04-27-2002, 08:37 PM

Yes, I would think that you should be able to get the carb parts though napa. If not they should be able to point you in the right direction. Good luck

------------------
71 SWB Stepside, was a 250, now is a 402 Big Block with 4 speed and 3.73's

72 LWB 4x4 350 4-speed 3.08's posi wearing army olive drab green (SOLD!)

68 BURB 50TH LOOKALIKE with built 350 4-speed 4.11's and posi

**COBALT** · 04-27-2002, 08:39 PM

Never mind. There's a new accel. pump assembly in the kit! hehe

I think all I need now is a new filter and a new float...then I'll start. Gordo has been nice enough to offer help.

------------------
'69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed!
'69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast).
Seattle, WA.

*See pics of my trucks and project at www.webshots.com!

Gordo · 04-27-2002, 08:40 PM

That kit should have a pump in it. It should be a small rubber gasket/seal looking thing aprox 5/8" in diameter, a hole in the middle and about 3/16" thick. It may be black, brown or blue in color. Some have a round spring wrapped inside the lip of the seal. How's that,,,clear as mud?

------------------
1971 C10 swb stepside 350/700R4/3.73posi
Killingworth, Connecticut

Cal69Chevy · 04-27-2002, 10:12 PM

New69Owner...I was in a similar situation just a few weeks ago except it was a 4bbl. I had never rebuilt a carb before and was able to do it pretty easily. So, definitely go for it...mine was running awful and now is super smooth.

don t. - 72gmc · 04-28-2002, 06:17 AM

Ditto what cal said. I'd done 2 bbl but not 4bbl. Instruction sheet in kit was good 4 me. I also used this website www.carbs.net
FWIW....don t. ....

------------------
It aint gonna be a trailer queen, its gotta work, just like me.
3/4 ton,350 w/HEI, 79 q-jet, th400.

[This message has been edited by don t. - 72gmc (edited April 28, 2002).]

[This message has been edited by don t. - 72gmc (edited April 28, 2002).]

**COBALT** · 04-28-2002, 11:51 AM

Thanks a lot guys. No I can't wait to get started. I'm going to get an internal filter and float before I tear it apart though...

...clear as mud Gordo. Everything you described is in the kit...

------------------
'69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed!
'69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast).
Seattle, WA.

*See pics of my trucks and project at www.webshots.com!

**COBALT** · 04-30-2002, 10:57 AM

I finally got the float and filter. Easy through NAPA. They still carry all of those parts.

Too bad I was stuck looking for that stuff on a Sunday. Those cheapie parts stores (Schucks/Checkers) are worthless as t!ts on a boar:

"...um...what do you need?"

"I said I needed a fuel inlet filter and a float for a Rochester 2bbl carb"

"...um...let me look in my book..."

[20 minutes later]

"...we don't carry anything like that."

Gimme a break.

------------------
'69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed!
'69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast).
Seattle, WA.

*See pics of my trucks and project at www.webshots.com!

04-12-2002, 03:01 PM	#1
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	Idle -> WOT: hesitates and chokes, then revs... I actually haven't gotten around to rebuilding my little Rochester 2G carb (bad boy), so I'm being lazy right now. Why is my carb. hesitating (badly), then causing this loud choke-sputter noise, and finally revs up when put full throttle from idle (idle to WOT)? Is it the metering of fuel from the bowl? The float? Or maybe those little bleed channels are plugged up that allow idle air? The throttle need adjusting? This may be a good learning experience for me. Anyone know what it is right off the top of their head? ------------------ '69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed! '69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast). Seattle, WA. *See pics of my trucks and project at www.webshots.com! __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

04-12-2002, 03:22 PM	#2
Gordo Registered User Join Date: Jan 2001 Location: Killingworth, CT. USA Posts: 3,378	Take a look down the throats of the carb, (engine off) and operate linkage from idle to WOT,,you should see two nice squirts of fuel as you do this,,if not your acelerator pump has had it,, time for rebuild. Other possiblities,,vaccum advance and timing. ------------------ 1971 C10 swb stepside 350/700R4/3.73posi Killingworth, Connecticut __________________ 1971 C10 swb stepside 350/700R4/3.73posi (retired as of 4/22/03) 1998 S10 short bed 2002 S10 Blazer 1942 Oldsmobile 1958 Massey Harris Pony 1951 Wife Killingworth, Connecticut May those who love us, love us, any of those who do not love us, may God turn their hearts. And if God is unable to turn their hearts, may he turn their ankles so we may know them by their limping. A man who works with his hands is a laborer; a man who works with his hands and his brain is a craftsman; but a man who works with his hands and his brain and his heart is an artist.

04-27-2002, 05:07 PM	#3
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	Well, I did what Gordo suggested and I think he's right. From idle to WOT with engine off I'm barely getting fuel out of either jet. Mainly just dribbles. After a couple of times I can sometimes get a definite jet out of the passenger side, but not the driver's side ever. What next? Accel pump? I assume I'm going to have to look for some hard parts somewhere... ------------------ '69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed! '69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast). Seattle, WA. *See pics of my trucks and project at www.webshots.com! __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

04-27-2002, 05:14 PM	#4
Benrs86 Registered User Join Date: Feb 2000 Location: Brandon, SD, USA Posts: 1,292	yeah, you should get a nice hard squirt of fuel. get a accellarator pump but if i were you while i had it all apart, soak it good in carb cleaner(not the spray kind) and do a little rebuild. good luck, Ben __________________ Brandon, SD 69 GMC 1/2 ton 2wd wide long bed with wood 3 on the tree 350 engine 4 bolt main rv cam AIM = Alphray04

04-27-2002, 08:24 PM	#5
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	I have the rebuild kit (which includes all the little gaskets and crap), and a huge can of carb cleaner. I was going to take all the hard parts and just let them soak over night. I wonder if I can even get accelerator pump parts for the carb through NAPA??? ------------------ '69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed! '69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast). Seattle, WA. *See pics of my trucks and project at www.webshots.com! __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

04-27-2002, 08:37 PM	#6
71402BB now thats a true COON DOG Join Date: Nov 2000 Location: Franconia, NH Posts: 1,977	Yes, I would think that you should be able to get the carb parts though napa. If not they should be able to point you in the right direction. Good luck ------------------ 71 SWB Stepside, was a 250, now is a 402 Big Block with 4 speed and 3.73's 72 LWB 4x4 350 4-speed 3.08's posi wearing army olive drab green (SOLD!) 68 BURB 50TH LOOKALIKE with built 350 4-speed 4.11's and posi __________________ current project 67 402BB stout th350 3.08's with a locker. Plan on tubs 18.5's out back! (thanks Burnsman!) 71 SWB Stepside, was a 250, now is a 402 Big Block with 4 speed and 3.73's ( was crushed by a tree, bed sold, motor pulled) was my first truck!... oh well... 72 LWB 4x4 350 4-speed 3.08's posi wearing army olive drab green (SOLD!) 68 BURB 50TH LOOKALIKE work in progress, soon to have 250-I6 with a 3-speed on the tree 4.11's and posi ( currently sitting in back yard tarped awaiting time, $$$, and lots of love!) 67 1 TON- work truck 396 sm 420 4-speed, flat bed 4.57 gears "big red" (my first landscape truck, very rusty and crusty! but still gets the job done when needed!)

04-27-2002, 08:39 PM	#7
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	Never mind. There's a new accel. pump assembly in the kit! hehe I think all I need now is a new filter and a new float...then I'll start. Gordo has been nice enough to offer help. ------------------ '69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed! '69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast). Seattle, WA. *See pics of my trucks and project at www.webshots.com! __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

04-27-2002, 08:40 PM	#8
Gordo Registered User Join Date: Jan 2001 Location: Killingworth, CT. USA Posts: 3,378	That kit should have a pump in it. It should be a small rubber gasket/seal looking thing aprox 5/8" in diameter, a hole in the middle and about 3/16" thick. It may be black, brown or blue in color. Some have a round spring wrapped inside the lip of the seal. How's that,,,clear as mud? ------------------ 1971 C10 swb stepside 350/700R4/3.73posi Killingworth, Connecticut __________________ 1971 C10 swb stepside 350/700R4/3.73posi (retired as of 4/22/03) 1998 S10 short bed 2002 S10 Blazer 1942 Oldsmobile 1958 Massey Harris Pony 1951 Wife Killingworth, Connecticut May those who love us, love us, any of those who do not love us, may God turn their hearts. And if God is unable to turn their hearts, may he turn their ankles so we may know them by their limping. A man who works with his hands is a laborer; a man who works with his hands and his brain is a craftsman; but a man who works with his hands and his brain and his heart is an artist.

04-27-2002, 10:12 PM	#9
Cal69Chevy Registered User Join Date: Nov 2001 Location: SoCal Posts: 136	New69Owner...I was in a similar situation just a few weeks ago except it was a 4bbl. I had never rebuilt a carb before and was able to do it pretty easily. So, definitely go for it...mine was running awful and now is super smooth. __________________ '69 Chevy, 4X4-SB 350 TBI-TH350 Trans-205 Transfer Case-Dana 44 Front-14 Bolt Rear-Front Disc Brakes-Factory A/C-P/S Ken's '69 Page

04-28-2002, 06:17 AM	#10
don t. - 72gmc Registered User Join Date: Dec 2001 Location: harvard, il. USA Posts: 394	Ditto what cal said. I'd done 2 bbl but not 4bbl. Instruction sheet in kit was good 4 me. I also used this website www.carbs.net FWIW....don t. .... ------------------ It aint gonna be a trailer queen, its gotta work, just like me. 3/4 ton,350 w/HEI, 79 q-jet, th400. [This message has been edited by don t. - 72gmc (edited April 28, 2002).] [This message has been edited by don t. - 72gmc (edited April 28, 2002).]

04-28-2002, 11:51 AM	#11
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	Thanks a lot guys. No I can't wait to get started. I'm going to get an internal filter and float before I tear it apart though... ...clear as mud Gordo. Everything you described is in the kit... ------------------ '69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed! '69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast). Seattle, WA. *See pics of my trucks and project at www.webshots.com! __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

04-30-2002, 10:57 AM	#12
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	I finally got the float and filter. Easy through NAPA. They still carry all of those parts. Too bad I was stuck looking for that stuff on a Sunday. Those cheapie parts stores (Schucks/Checkers) are worthless as t!ts on a boar: "...um...what do you need?" "I said I needed a fuel inlet filter and a float for a Rochester 2bbl carb" "...um...let me look in my book..." [20 minutes later] "...we don't carry anything like that." Gimme a break. ------------------ '69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed! '69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast). Seattle, WA. *See pics of my trucks and project at www.webshots.com! __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.



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