Start up problem's - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**FRENCHBLUE72** · 09-30-2003, 08:41 PM

The quadrajet carb on my blazer seem's to be having problem's starting. The truck will not start unless I prime the carb with gas first then it crank's and fire's first try.. Could it be my fuel pump??? The carb spray's gas but the filter has very little fuel in it . Any help or suggestion's would be great.. Thank's Luke

Longhorn Man · 09-30-2003, 08:50 PM

That is all pretty much normal.
Fuel injection will automaticly squirt fuel into the combustion chaimber (or throttle body) when you crank it. A carb relys on engine vacume to do this, and at 400 RPM 9aprox RPM your starter turns the engine over at) does not provide enough vacume to draw the fuel into the carb. Any unburned fuel in the carb will evaporate after a moment or two, so you have to pump it in most carb aplications.
As for the fuel filter being 1/2 full, I have no explination, but it is also pretty much the norm.

Gordo · 09-30-2003, 09:21 PM

Is this only when it's cold? If so, is the choke working and adjusted? Once it's running does it hesitate? With engine off, do you see two nice squirts of fuel down in the primary throats when you operate the linkage to wide open throttle? If not, you may have accelerator pump problems. If the choke is not set right and the accelerator pump isn't working it would give you those symptoms.

PanelDeland · 09-30-2003, 10:09 PM

Had a buddy with a 57.He rebuilt carb,replaced fuel pump twice, still hadto prime it to get it started.After about a year he sold it.The next owner was going to put a fuel cell in to prevent the problem, but found the old tank to metal fuel line was cracked.$2.00 worth of rubber fuel line solved the problem.

Pick the low hanging fruit first.(try the simplest stuff first)

**FRENCHBLUE72** · 09-30-2003, 11:39 PM

Thank's guy's... Where to start. No choke, only does it when it is cold when it is warm not even half a engine revolution before it start's.Two nice squirt's of fuel down carb when motor is warm or cold. The fuel filter is like 1/8 full if that. Fuel filter is mounted up and down only gas in one corner on filter??? What else should I look at it could be acc pump???

jhow66 · 10-01-2003, 11:02 AM

If choke blade is still there close it by hand and have someone start it. If it starts you have found problem--fix choke

tom hand · 10-01-2003, 11:40 AM

Are you saying you have to manually pour gas in the carb? On 72's they had the return line to the gas tank and I have seen them cause problems. If you have the original style fuel pump use some vice grips and crimp the small rubber line closed. [there should be two] If it improves I would consider replacing the fuel pump with one that does not have the return...or just block it off permanently

cdowns · 10-01-2003, 12:01 PM

there's a fuel filter in the carb inlet have you checked that?? sounds like it may be clogged. you remove the fuel line and the filter is inside the large fitting on the carb where the fuel line goes to

**FRENCHBLUE72** · 10-01-2003, 06:50 PM

No choke blade is there. Yes I manually pour gas in the carb. No fuel line return. And both filter's are new ...

Class of 69 · 10-01-2003, 06:55 PM

When GM went to the fuel return system, they had to install a check valve in the in-carb filter. If the filter you have doesn't have the check valve in it, try one that does and see what happens.

Gordo · 10-01-2003, 07:32 PM

Sounds like you need a operating choke assembly in order to cure the cold start up problem, be it an automatic or manual choke.

lukecp · 10-01-2003, 07:49 PM

Yup...no choke blade is your problem. I would get your Q-jet's choke working

-OR-

Buy an edelbrock 1406 with an electric choke. Prime the truck with 2 pumps to the floor, hit the key and it will start right up in the dead of winter.

jorgensensc · 10-01-2003, 08:14 PM

I've got the 1406 on an rpm air gap. And your right, 2 pumps and she starts right up, The electric choke idles her high until I feel she's warmed up, then I tap the gas and she idles normally. Never had her stall once on me( unlike my '82 that always stalled in reverse when she was cold)

lukecp · 10-01-2003, 08:41 PM

That is my favorite thing with the 1406....very easy to warm up

I need to adjust the choke a little to the richer side....winter is just around the corner

**FRENCHBLUE72** · 10-01-2003, 10:02 PM

Should I really need a choke in 95 degree weather???? We do not even have a choke horn on the carb on the race car why would I need one in street truck??? Thank's for all the info guy's I will screw with it in the morning...

Longhorn Man · 10-01-2003, 11:02 PM

I was under the impression you ment priming it as in pumping the throttle, not dumping a cup of gas into the carb.

09-30-2003, 08:41 PM	#1
FRENCHBLUE72 PROJECT 7DEUCE Join Date: Dec 2002 Location: GRANTS PASS OR Posts: 21,603	Start up problem's The quadrajet carb on my blazer seem's to be having problem's starting. The truck will not start unless I prime the carb with gas first then it crank's and fire's first try.. Could it be my fuel pump??? The carb spray's gas but the filter has very little fuel in it . Any help or suggestion's would be great.. Thank's Luke __________________ GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P..

09-30-2003, 09:21 PM	#3
Gordo Registered User Join Date: Jan 2001 Location: Killingworth, CT. USA Posts: 3,378	Is this only when it's cold? If so, is the choke working and adjusted? Once it's running does it hesitate? With engine off, do you see two nice squirts of fuel down in the primary throats when you operate the linkage to wide open throttle? If not, you may have accelerator pump problems. If the choke is not set right and the accelerator pump isn't working it would give you those symptoms. __________________ 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.

09-30-2003, 10:09 PM	#4
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,993	Had a buddy with a 57.He rebuilt carb,replaced fuel pump twice, still hadto prime it to get it started.After about a year he sold it.The next owner was going to put a fuel cell in to prevent the problem, but found the old tank to metal fuel line was cracked.$2.00 worth of rubber fuel line solved the problem. Pick the low hanging fruit first.(try the simplest stuff first) __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil"

09-30-2003, 11:39 PM	#5
FRENCHBLUE72 PROJECT 7DEUCE Join Date: Dec 2002 Location: GRANTS PASS OR Posts: 21,603	Thank's guy's... Where to start. No choke, only does it when it is cold when it is warm not even half a engine revolution before it start's.Two nice squirt's of fuel down carb when motor is warm or cold. The fuel filter is like 1/8 full if that. Fuel filter is mounted up and down only gas in one corner on filter??? What else should I look at it could be acc pump??? __________________ GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P..

10-01-2003, 11:02 AM	#6
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	If choke blade is still there close it by hand and have someone start it. If it starts you have found problem--fix choke __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

09-30-2003, 08:50 PM	#2
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	That is all pretty much normal. Fuel injection will automaticly squirt fuel into the combustion chaimber (or throttle body) when you crank it. A carb relys on engine vacume to do this, and at 400 RPM 9aprox RPM your starter turns the engine over at) does not provide enough vacume to draw the fuel into the carb. Any unburned fuel in the carb will evaporate after a moment or two, so you have to pump it in most carb aplications. As for the fuel filter being 1/2 full, I have no explination, but it is also pretty much the norm.

10-01-2003, 11:40 AM	#7
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	Are you saying you have to manually pour gas in the carb? On 72's they had the return line to the gas tank and I have seen them cause problems. If you have the original style fuel pump use some vice grips and crimp the small rubber line closed. [there should be two] If it improves I would consider replacing the fuel pump with one that does not have the return...or just block it off permanently __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS

10-01-2003, 12:01 PM	#8
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	there's a fuel filter in the carb inlet have you checked that?? sounds like it may be clogged. you remove the fuel line and the filter is inside the large fitting on the carb where the fuel line goes to __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

10-01-2003, 06:50 PM	#9
FRENCHBLUE72 PROJECT 7DEUCE Join Date: Dec 2002 Location: GRANTS PASS OR Posts: 21,603	No choke blade is there. Yes I manually pour gas in the carb. No fuel line return. And both filter's are new ... __________________ GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P..

10-01-2003, 06:55 PM	#10
Class of 69 Registered User Join Date: Mar 2003 Location: Stillwater MN Posts: 1,166	When GM went to the fuel return system, they had to install a check valve in the in-carb filter. If the filter you have doesn't have the check valve in it, try one that does and see what happens. __________________ 69 GMC K10 ..some restoration required....still..

10-01-2003, 07:32 PM	#11
Gordo Registered User Join Date: Jan 2001 Location: Killingworth, CT. USA Posts: 3,378	Sounds like you need a operating choke assembly in order to cure the cold start up problem, be it an automatic or manual choke. __________________ 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.

10-01-2003, 07:49 PM	#12
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	Yup...no choke blade is your problem. I would get your Q-jet's choke working -OR- Buy an edelbrock 1406 with an electric choke. Prime the truck with 2 pumps to the floor, hit the key and it will start right up in the dead of winter. __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

10-01-2003, 08:14 PM	#13
jorgensensc Registered User Join Date: Jul 2003 Location: Cypress, Tx Posts: 4,005	I've got the 1406 on an rpm air gap. And your right, 2 pumps and she starts right up, The electric choke idles her high until I feel she's warmed up, then I tap the gas and she idles normally. Never had her stall once on me( unlike my '82 that always stalled in reverse when she was cold)

10-01-2003, 08:41 PM	#14
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	That is my favorite thing with the 1406....very easy to warm up I need to adjust the choke a little to the richer side....winter is just around the corner __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

10-01-2003, 10:02 PM	#15
FRENCHBLUE72 PROJECT 7DEUCE Join Date: Dec 2002 Location: GRANTS PASS OR Posts: 21,603	Should I really need a choke in 95 degree weather???? We do not even have a choke horn on the carb on the race car why would I need one in street truck??? Thank's for all the info guy's I will screw with it in the morning... __________________ GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P..



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10-01-2003, 11:02 PM	#16
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	I was under the impression you ment priming it as in pumping the throttle, not dumping a cup of gas into the carb.

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