Engine "burps" when you stomp on it??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

HotRod929 · 09-04-2002, 05:55 PM

When i am driving along and all of a sudden I stomp on the accelerator the engine sortof hesitates and then gos. This has scared the crap out of me when I am trying to beat the light.

Is it a carb problem thats out of adjustment or is it something else? Thanks

HotRod

**COBALT** · 09-04-2002, 05:57 PM

That was happening to me when my accelerator pump was broke in my carb. Once I rebuilt the carb, and advanced the timing the hesitation + hiss and POP went away. Now it's VERY responsive. Didn't know what I was missing.

HotRod929 · 09-04-2002, 06:00 PM

But the thing is that it only does it some of the time. Not all the time.

HotRod

Tyler_69C10 · 09-04-2002, 06:33 PM

What kind of carb do you have?

HotRod929 · 09-04-2002, 07:09 PM

Not a clue/ Its and old grungey 4 barrel of some sorts

RipMeyer · 09-04-2002, 07:23 PM

Two things come to mind.

Check the Timing and Carb.

**COBALT** · 09-04-2002, 07:49 PM

...which is what I said. It might depend on whether or not your engine is warmed up. Mine wouldn't do that when it was cold because it was running rich. It usually happened when the truck was warm.

It's not going to hurt to check your timing. What kind of ignition do you have?

lectricman · 09-04-2002, 08:48 PM

i have the same prob so i invested in a new holly 600 and that seemed to help a little but didnt cure it so i had a mechanic that works on our bakery trucks look at it and he crawled underneath and turned the harmonic balancer almost an inch with no prob and said that he could do that because the timing chain is stretched/needs replaced so i asked if he could fix it for me and he said sure...i beleive that i am going to have him install a performance cam and lifters while he has the front of the motor apart...wish me luck and i hope this might help...Anthony

HotRod929 · 09-04-2002, 08:54 PM

So basically what your saying lectricman is my timing chain is all streched out and I need a new one? Are these hard to put in? What about those gear driven thingys?

wcdrake · 09-05-2002, 03:48 PM

make sure you dont overlook the obvious... I am embarrassed to say but I have been fighting carb problems for longer than I want to admit but found it to be a 75 cent fix. My blazer had a serious bog off idle then once I shot enough fuel into the carb from the accel pump, it took off and ran great. Occasionally I would get a pop through the carb if really stomped on it. Well I started by rebuilding my carb, tune up (wires, cap, rotor, plugs, the works) and even considered a vacuum leak around the intake manifold. Well as dumb luck would have it, I was looking at the motor one night and thought that the vacuum advance might be the problem, I decided to check the hose from the advance diaphram to the carb. I dont know why because looking at the hose, it looked brand new. While I was sliding my hand along the hose, I felt a burnt area on the bottom side of the hose. Sure enough, there was a huge hole in it though it was hidden from plain view. Out of all this, I finally got my blazer back at full force and because of all the other work, better gas mileage, performance and piece of mind... haha good luck

jku72 · 09-05-2002, 04:19 PM

Back the bus up.
This is such a common problem that is relativly easy to fix, providing your carb is the likely original Quadrajet. This problem even has it's own name, quadra bog.
Anyway, it is all in the secondary air flapper spring adjustment. The secondaries are the bigger two holes, and when you floor it, they open on air pressure, or, more accuratly, lack therof, also known as vaccuum. The spring gets old, and weak, and then what happens is that the flapper opens too soon, the mixture gets way out of whack, the engine acts like it quits for a second, then maybe backfires, then grabs and goes like a raped ape. Or, in a bad case, as my truck once had, would not recover till you get out of the throttle, then slowly reapply.
Anyway, all you have to do is locate the impossibbly small allen head set screw on the flapper spring housing, then turn the spring a little tighter, retighten the impossibly small set screw, and voila! Bog be gone. A Book on q jets is in order, as I realize my description of events is...well...lacking in detail sufficient to do the job. But, it is a simple fix, requires no money, just some bad language. And eye squinting.

HotRod929 · 09-05-2002, 05:43 PM

Yea a little more info on that fix jku72 would be nice. The burp is really starting to piss me off. THanks

HotRod

09-04-2002, 05:55 PM	#1
HotRod929 Registered User Join Date: Mar 2002 Location: Bondurant, IA but in Worcester, MA for school Posts: 767	Engine "burps" when you stomp on it??? When i am driving along and all of a sudden I stomp on the accelerator the engine sortof hesitates and then gos. This has scared the crap out of me when I am trying to beat the light. Is it a carb problem thats out of adjustment or is it something else? Thanks HotRod __________________ 1970 Chevy C-20 350 V-8 Turbo 350 w/ shift kit Dana 60 w/ 4.10 gears AND Powr-Loc POSI New Additions: Summit Headers 135amp alternator Proform HEI Edelbrock 1406 600cfm carb Sunpro Tach Powr-Loc POSI Edelbrock Performer RPM Intake MSD 6A Ignition Box AIM: HotRod929 Visit My Site: http://1970chevy.netfirms.com/

09-04-2002, 05:57 PM	#2
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	That was happening to me when my accelerator pump was broke in my carb. Once I rebuilt the carb, and advanced the timing the hesitation + hiss and POP went away. Now it's VERY responsive. Didn't know what I was missing. __________________ '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.

09-04-2002, 06:00 PM	#3
HotRod929 Registered User Join Date: Mar 2002 Location: Bondurant, IA but in Worcester, MA for school Posts: 767	But the thing is that it only does it some of the time. Not all the time. HotRod __________________ 1970 Chevy C-20 350 V-8 Turbo 350 w/ shift kit Dana 60 w/ 4.10 gears AND Powr-Loc POSI New Additions: Summit Headers 135amp alternator Proform HEI Edelbrock 1406 600cfm carb Sunpro Tach Powr-Loc POSI Edelbrock Performer RPM Intake MSD 6A Ignition Box AIM: HotRod929 Visit My Site: http://1970chevy.netfirms.com/

09-04-2002, 06:33 PM	#4
Tyler_69C10 Registered User Join Date: May 2002 Location: Sidney, BC, Canada Posts: 63	What kind of carb do you have? __________________ 1969 Chevy C/10 LWB A great work truck!

09-04-2002, 07:09 PM	#5
HotRod929 Registered User Join Date: Mar 2002 Location: Bondurant, IA but in Worcester, MA for school Posts: 767	Not a clue/ Its and old grungey 4 barrel of some sorts __________________ 1970 Chevy C-20 350 V-8 Turbo 350 w/ shift kit Dana 60 w/ 4.10 gears AND Powr-Loc POSI New Additions: Summit Headers 135amp alternator Proform HEI Edelbrock 1406 600cfm carb Sunpro Tach Powr-Loc POSI Edelbrock Performer RPM Intake MSD 6A Ignition Box AIM: HotRod929 Visit My Site: http://1970chevy.netfirms.com/

09-04-2002, 07:23 PM	#6
RipMeyer Registered User Join Date: Oct 2001 Location: Southern New Mexico Posts: 649	Two things come to mind. Check the Timing and Carb.

09-04-2002, 07:49 PM	#7
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	...which is what I said. It might depend on whether or not your engine is warmed up. Mine wouldn't do that when it was cold because it was running rich. It usually happened when the truck was warm. It's not going to hurt to check your timing. What kind of ignition do you have? __________________ '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.

09-04-2002, 08:48 PM	#8
lectricman Registered User Join Date: Aug 2002 Location: Huntington,West Virginia Posts: 6	i have the same prob so i invested in a new holly 600 and that seemed to help a little but didnt cure it so i had a mechanic that works on our bakery trucks look at it and he crawled underneath and turned the harmonic balancer almost an inch with no prob and said that he could do that because the timing chain is stretched/needs replaced so i asked if he could fix it for me and he said sure...i beleive that i am going to have him install a performance cam and lifters while he has the front of the motor apart...wish me luck and i hope this might help...Anthony

09-04-2002, 08:54 PM	#9
HotRod929 Registered User Join Date: Mar 2002 Location: Bondurant, IA but in Worcester, MA for school Posts: 767	So basically what your saying lectricman is my timing chain is all streched out and I need a new one? Are these hard to put in? What about those gear driven thingys? __________________ 1970 Chevy C-20 350 V-8 Turbo 350 w/ shift kit Dana 60 w/ 4.10 gears AND Powr-Loc POSI New Additions: Summit Headers 135amp alternator Proform HEI Edelbrock 1406 600cfm carb Sunpro Tach Powr-Loc POSI Edelbrock Performer RPM Intake MSD 6A Ignition Box AIM: HotRod929 Visit My Site: http://1970chevy.netfirms.com/

09-05-2002, 03:48 PM	#10
wcdrake Registered User Join Date: Jul 2002 Posts: 14	make sure you dont overlook the obvious... I am embarrassed to say but I have been fighting carb problems for longer than I want to admit but found it to be a 75 cent fix. My blazer had a serious bog off idle then once I shot enough fuel into the carb from the accel pump, it took off and ran great. Occasionally I would get a pop through the carb if really stomped on it. Well I started by rebuilding my carb, tune up (wires, cap, rotor, plugs, the works) and even considered a vacuum leak around the intake manifold. Well as dumb luck would have it, I was looking at the motor one night and thought that the vacuum advance might be the problem, I decided to check the hose from the advance diaphram to the carb. I dont know why because looking at the hose, it looked brand new. While I was sliding my hand along the hose, I felt a burnt area on the bottom side of the hose. Sure enough, there was a huge hole in it though it was hidden from plain view. Out of all this, I finally got my blazer back at full force and because of all the other work, better gas mileage, performance and piece of mind... haha good luck

09-05-2002, 04:19 PM	#11
jku72 Registered User Join Date: Jan 2002 Location: cornville, maine Posts: 659	Back the bus up. This is such a common problem that is relativly easy to fix, providing your carb is the likely original Quadrajet. This problem even has it's own name, quadra bog. Anyway, it is all in the secondary air flapper spring adjustment. The secondaries are the bigger two holes, and when you floor it, they open on air pressure, or, more accuratly, lack therof, also known as vaccuum. The spring gets old, and weak, and then what happens is that the flapper opens too soon, the mixture gets way out of whack, the engine acts like it quits for a second, then maybe backfires, then grabs and goes like a raped ape. Or, in a bad case, as my truck once had, would not recover till you get out of the throttle, then slowly reapply. Anyway, all you have to do is locate the impossibbly small allen head set screw on the flapper spring housing, then turn the spring a little tighter, retighten the impossibly small set screw, and voila! Bog be gone. A Book on q jets is in order, as I realize my description of events is...well...lacking in detail sufficient to do the job. But, it is a simple fix, requires no money, just some bad language. And eye squinting. __________________ jku Cornville, Maine 68 C10 burb 42 Willys MB 46 Dodge WF-32 1.5 ton 53 & 56 Olds' 60 Cadillac 22 Dodge Brothers

09-05-2002, 05:43 PM	#12
HotRod929 Registered User Join Date: Mar 2002 Location: Bondurant, IA but in Worcester, MA for school Posts: 767	Yea a little more info on that fix jku72 would be nice. The burp is really starting to piss me off. THanks HotRod __________________ 1970 Chevy C-20 350 V-8 Turbo 350 w/ shift kit Dana 60 w/ 4.10 gears AND Powr-Loc POSI New Additions: Summit Headers 135amp alternator Proform HEI Edelbrock 1406 600cfm carb Sunpro Tach Powr-Loc POSI Edelbrock Performer RPM Intake MSD 6A Ignition Box AIM: HotRod929 Visit My Site: http://1970chevy.netfirms.com/



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