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#1 |
PROJECT 7DEUCE
![]() Join Date: Dec 2002
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Posts: 21,608
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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
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GO BIG GREEN ![]() 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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#2 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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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. |
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#3 |
Registered User
Join Date: Jan 2001
Location: Killingworth, CT. USA
Posts: 3,378
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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.
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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. |
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#4 |
I am a Referee of life.
Join Date: Jun 2000
Location: Greensboro N.C.
Posts: 13,993
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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)
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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" |
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#5 |
PROJECT 7DEUCE
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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???
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GO BIG GREEN ![]() 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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#6 |
Registered User
Join Date: Jun 2002
Location: Knoxville Tenn.
Posts: 3,058
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If choke blade is still there close it by hand and have someone start it. If it starts you have found problem--fix choke
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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 |
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#7 |
CCRider
Join Date: Feb 2000
Location: Olive Branch,MS,USA
Posts: 2,232
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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
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72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS |
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#8 |
Senior Member
Join Date: Jan 2003
Location: daytonabeach
Posts: 22,956
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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
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#9 |
PROJECT 7DEUCE
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No choke blade is there. Yes I manually pour gas in the carb. No fuel line return. And both filter's are new ...
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GO BIG GREEN ![]() 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 |
Registered User
Join Date: Mar 2003
Location: Stillwater MN
Posts: 1,166
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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.
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69 GMC K10 ..some restoration required....still.. ![]() |
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#11 |
Registered User
Join Date: Jan 2001
Location: Killingworth, CT. USA
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Sounds like you need a operating choke assembly in order to cure the cold start up problem, be it an automatic or manual choke.
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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. |
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#12 |
Formerly yellow72custom
Join Date: May 2001
Location: Austin, TX
Posts: 7,531
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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.
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'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 |
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#13 |
Registered User
Join Date: Jul 2003
Location: Cypress, Tx
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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)
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#14 |
Formerly yellow72custom
Join Date: May 2001
Location: Austin, TX
Posts: 7,531
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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 ![]()
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'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 |
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#15 |
PROJECT 7DEUCE
![]() Join Date: Dec 2002
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Posts: 21,608
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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...
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GO BIG GREEN ![]() 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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#16 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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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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