Bad Accelerator Pump? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Shaffer4 · 12-20-2008, 10:32 PM

My K20 ('67 on a '72 frame) has a little carb issue. It has an Edelbrock Q-Jet carb. While driving around it drives fine some of the time (though it is always testy when leaving from a stop.), but every few minutes it will start stalling and missing and spitting and Popping and if I let off the gas it dies, to keeping running during this phase requires copious amounts of throttle. After a few minutes of this tango it will even out for a few minutes and then repeat. Make driving in traffic a nightmare I can tell you... and with all the snow on the ground it is ten fold.

I originally thought it may have been the choke, as the previous owner had not hooked up the electric Choke, I fixed that and it made little difference.

Edit: 350ci/G-4speed/np205

neonlarry · 12-20-2008, 11:01 PM

Sounds more like bad fuel pump/clogged fuel filter/clogged needle valve. Bad accelerator pump would fall on its face every time you stepped down on the gas not at cruise.

yotaforce · 12-21-2008, 12:19 AM

I call them "Quadra-bogs". I have thrown away atleast five. Just my opinion.

Shaffer4 · 12-21-2008, 01:57 AM

Filter is clean/new.

Shaffer4 · 12-21-2008, 02:02 AM

all I have around Carbwise other than that is a 500cfm Carter Almost Four Barrel on my 81's 305, a 700cfm Edelbrock Almost Four Barrel (I think I still have this), a 770 Holley Street Avenger off of my 454, and the 900cfm Holley Three sitting on my 454... ( Oh I probably have a 600 Holley and the two 500s for my SBF Tunnel Ram... )

I have a fuel pump that I bought for the '81 when I thought it went bad last winter, but I don't know if there are any differences between that pump and my current one and if it will work.

Shaffer4 · 12-21-2008, 02:35 AM

Also, the Fuel Filter stays full of gas.

neonlarry · 12-21-2008, 10:25 AM

When you say new filter and it stays full of gas, do you mean an inline filter seperate from the one in the carb? If so was the one in the carb changed or removed?

Shaffer4 · 12-21-2008, 06:37 PM

There is a clear Inline and the in carb filter, both are new.

72gmcworker · 12-21-2008, 08:37 PM

Water in the gas???????

It will collect in the in carb filter preventing fuel from getting through the filter starving the carb. and causing all sorts of hicups, poor idling, etc as you mentioned ...also when the water gets into the carb.
been there recently.
Pull the filter and drain it for signs of water.
And/Or drain the tank completly and start over with fresh fuel and fresh filters..again

12-20-2008, 10:32 PM	#1
Shaffer4 Strange Cousin From The West.. Join Date: Jul 2007 Location: Walla Walla, Wa Posts: 248	Bad Accelerator Pump? My K20 ('67 on a '72 frame) has a little carb issue. It has an Edelbrock Q-Jet carb. While driving around it drives fine some of the time (though it is always testy when leaving from a stop.), but every few minutes it will start stalling and missing and spitting and Popping and if I let off the gas it dies, to keeping running during this phase requires copious amounts of throttle. After a few minutes of this tango it will even out for a few minutes and then repeat. Make driving in traffic a nightmare I can tell you... and with all the snow on the ground it is ten fold. I originally thought it may have been the choke, as the previous owner had not hooked up the electric Choke, I fixed that and it made little difference. Edit: 350ci/G-4speed/np205 Last edited by Shaffer4; 12-20-2008 at 10:34 PM.

12-20-2008, 11:01 PM	#2
neonlarry Registered User Join Date: Feb 2002 Location: Vacaville, CA Posts: 2,746	Re: Bad Accelerator Pump? Sounds more like bad fuel pump/clogged fuel filter/clogged needle valve. Bad accelerator pump would fall on its face every time you stepped down on the gas not at cruise. __________________ 70 C/10 Light Red 350/TH350, HEI, Duals w/40 series Flows, 91 seat, LED taillights 99 Pontiac S/C GTP, SLP Ram Air hood, GMPP Konis & springs 95 Neon ACR, MP PCM, AFX UDP, 3.0 CAI

12-21-2008, 12:19 AM	#3
yotaforce Registered User Join Date: Oct 2007 Location: Rutherfordton, NC Posts: 89	Re: Bad Accelerator Pump? I call them "Quadra-bogs". I have thrown away atleast five. Just my opinion.

12-21-2008, 01:57 AM	#4
Shaffer4 Strange Cousin From The West.. Join Date: Jul 2007 Location: Walla Walla, Wa Posts: 248	Re: Bad Accelerator Pump? Filter is clean/new.

12-21-2008, 02:02 AM	#5
Shaffer4 Strange Cousin From The West.. Join Date: Jul 2007 Location: Walla Walla, Wa Posts: 248	Re: Bad Accelerator Pump? all I have around Carbwise other than that is a 500cfm Carter Almost Four Barrel on my 81's 305, a 700cfm Edelbrock Almost Four Barrel (I think I still have this), a 770 Holley Street Avenger off of my 454, and the 900cfm Holley Three sitting on my 454... ( Oh I probably have a 600 Holley and the two 500s for my SBF Tunnel Ram... ) I have a fuel pump that I bought for the '81 when I thought it went bad last winter, but I don't know if there are any differences between that pump and my current one and if it will work. Last edited by Shaffer4; 12-21-2008 at 02:04 AM.

12-21-2008, 02:35 AM	#6
Shaffer4 Strange Cousin From The West.. Join Date: Jul 2007 Location: Walla Walla, Wa Posts: 248	Re: Bad Accelerator Pump? Also, the Fuel Filter stays full of gas.

12-21-2008, 10:25 AM	#7
neonlarry Registered User Join Date: Feb 2002 Location: Vacaville, CA Posts: 2,746	Re: Bad Accelerator Pump? When you say new filter and it stays full of gas, do you mean an inline filter seperate from the one in the carb? If so was the one in the carb changed or removed? __________________ 70 C/10 Light Red 350/TH350, HEI, Duals w/40 series Flows, 91 seat, LED taillights 99 Pontiac S/C GTP, SLP Ram Air hood, GMPP Konis & springs 95 Neon ACR, MP PCM, AFX UDP, 3.0 CAI

12-21-2008, 06:37 PM	#8
Shaffer4 Strange Cousin From The West.. Join Date: Jul 2007 Location: Walla Walla, Wa Posts: 248	Re: Bad Accelerator Pump? There is a clear Inline and the in carb filter, both are new. Last edited by Shaffer4; 12-21-2008 at 06:38 PM.

12-21-2008, 08:37 PM	#9
72gmcworker Registered User Join Date: May 2006 Location: North x Northwest BC Posts: 62	Re: Bad Accelerator Pump? Water in the gas??????? It will collect in the in carb filter preventing fuel from getting through the filter starving the carb. and causing all sorts of hicups, poor idling, etc as you mentioned ...also when the water gets into the carb. been there recently. Pull the filter and drain it for signs of water. And/Or drain the tank completly and start over with fresh fuel and fresh filters..again __________________ '70 Pontiac Firebird Esprit '72 GMC 2500 '90 GMC V1500 '94 Dodge Cummins 2500 '02 Dodge 2500 Quad Cab Long Box 4x4 gasser



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