| Hard to Start [message #100133] |
Fri, 17 September 2010 17:39  |
captjack
Messages: 271
Registered: February 2010
Location: Sebastopol, California
Karma: 1
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Senior Member |
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My GMC is hard to start. I've got an electric fuel pump and run it to fill the carb bowl, but it doesn't make much difference. I crank for around 5 seconds then pause and repeat. It usually takes at least 4 attempts and often more before I'm successful. Once it starts it runs OK. Once it's warm it starts promptly. I've checked the chose setting and varied it from too rich to too lean w/o much difference. Earlier I thought it was the HEI ignitor (which may have been part of the problem) so I replaced it. Not sure what to try next.
Jack Christensen - K6ROW,
'76 Glenbrook/Clasco - "The Silver Bullet",
Sebastopol, CA
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| Re: Hard to Start [message #100135 is a reply to message #100133] |
Fri, 17 September 2010 17:51  |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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| captjack wrote on Fri, 17 September 2010 18:39 |
My GMC is hard to start. I've got an electric fuel pump and run it to fill the carb bowl, but it doesn't make much difference. I crank for around 5 seconds then pause and repeat. It usually takes at least 4 attempts and often more before I'm successful. Once it starts it runs OK. Once it's warm it starts promptly. I've checked the chose setting and varied it from too rich to too lean w/o much difference. Earlier I thought it was the HEI ignitor (which may have been part of the problem) so I replaced it. Not sure what to try next.
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Sir: maybe with the engine off open top of air cleaner and mash the gas and see if the accelerator pump is squirting?
C. Boyd
76 Crestmont
East Tennessee
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| Re: [GMCnet] Hard to Start [message #100136 is a reply to message #100133] |
Fri, 17 September 2010 17:56 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Check your choke
On Fri, Sep 17, 2010 at 3:39 PM, Jack Christensen <captjack@sonic.net>wrote:
>
>
> My GMC is hard to start. I've got an electric fuel pump and run it to fill
> the carb bowl, but it doesn't make much difference. I crank for around 5
> seconds then pause and repeat. It usually takes at least 4 attempts and
> often more before I'm successful. Once it starts it runs OK. Once it's
> warm it starts promptly. I've checked the chose setting and varied it from
> too rich to too lean w/o much difference. Earlier I thought it was the HEI
> ignitor (which may have been part of the problem) so I replaced it. Not
> sure what to try next.
>
>
> --
> Jack Christensen - K6ROW
> '76 Glenbrook/Clasco
> Sebastopol, CA
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: Hard to Start [message #100221 is a reply to message #100133] |
Sat, 18 September 2010 10:03 |
Larry C
Messages: 1168
Registered: July 2004
Location: NE Illinois by the Illino...
Karma: 0
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Senior Member |
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My GMC is hard to start.
_________________________________________-
I've been there......
After my fuel system fiasco last year It has run, ( so far, knock on wood ) with a rebuilt carb.
But it has been hard to start also. at one point it was because of low fuel but I filled to half a tank and she was still hard to start, like no fuel.
I tried using Ether and she started and died. A couple tries and she ran normal.
I am guessing the float bowl is losing the fuel over a time sitting. Once I have ran the engine a bit and shut down, she will start up fine.
I should add, I have a mechanical fuel pump, no electric pump.
I have attributed my start up problem with fuel components, carborator that has been on the engine for years but all this stuff was rebuilt so I can't say why it happens at this time...
Just what I did.
Gatsbys' CRUISER  08-18-04
74 GLACIER X, 260/455-APC-4 Bagg'r
Remflex Manifold gaskets
CampGrounds needed, Add yours to "PLACES" />
http://www.gmceast.com/travel
_
[Updated on: Sat, 18 September 2010 10:04] Report message to a moderator |
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| Re: [GMCnet] Hard to Start [message #100225 is a reply to message #100221] |
Sat, 18 September 2010 10:37 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Quadrajet carbs are bolted down on all 4 corners. The rear 2 bolts go only
through the throttle body portion of the carb which is iron. The front 2
bolts go completely through the air horn, float chamber and finally the
throttle body. Check the base of the carb with a straight edge to see if
overtightening or uneven tightening has warped the base of the carb. Also
check the base gasket/isolator. The good ones have spools through the gasket
to absorb the torque from the hold down bolts, but after they age a bit, the
spools act like separators & take the clamping load. There is frequently a
vacuum leak under the carb when cold that closes up when the engine warms
up. This will cause cold starting problems that are intermittent in nature
and make them very hard to find. Also take your mityvac tool and check the
choke vacuum pulloff. They also frequently fail and do not open the choke
when they are supposed to. It goes without saying that the choke should be
set on a COLD engine. If yours has three screws on the choke housing, loosen
them but don't take them completely out. Turn the choke housing while
watching the choke plate until the choke plate is fully open. Turn the choke
housing back the other way while observing the choke plate. When it just
touches closed, tighten the screws. Leave the air cleaner off and start the
engine. As the engine warms, the choke should open fully. On a warmed up
engine, the thermostatic spring should hold it open with enough force that
it will return to the full open position when you try to close it with your
fingers. If it fails to operate like this, replace it. I know Jim K has them
in stock. Hot start problems are a whole different deal.
Jim Hupy
Salem, Or
78 Royale 403
On Sat, Sep 18, 2010 at 8:03 AM, Larry <slawrence111@yahoo.com> wrote:
>
>
> My GMC is hard to start.
> _________________________________________-
>
> I've been there......
> After my fuel system fiasco last year It has run, ( so far, knock on wood )
> with a rebuilt carb.
>
> But it has been hard to start also. at one point it was because of low
> fuel but I filled to half a tank and she was still hard to start, like no
> fuel.
>
> I tried using Ether and she started and died. A couple tries and she ran
> normal.
>
> I am guessing the float bowl is losing the fuel over a time sitting. Once
> I have ran the engine a bit and shut down, she will start up fine.
>
> I have attributed my start up problem with fuel components, carborator that
> has been on the engine for years but all this stuff was rebuilt so I can't
> say why it happens at this time...
>
> Just what I did.
>
> --
> Gatsbys' CRUISER :d
> 74 GLACIER X, 260
> 455/APC/4 bagg'r(ver3)
> Remflex Manifold gaskets
> _______________________________________________
> Purchased 08-18-04
>
> _
>
>
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: Hard to Start [message #100396 is a reply to message #100133] |
Sun, 19 September 2010 21:16 |
captjack
Messages: 271
Registered: February 2010
Location: Sebastopol, California
Karma: 1
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Senior Member |
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Thanks to all who replied. I discovered a number of problems you pointed out.
- The Choke wasn't set right.
- The choke mechanism was binding and needed some carb cleaner to free it up
- The choke vacuum pulloff had failed.
To replace the pulloff I'll need to remove the carb and can check for a vacuum leak at the interface w/ the intake manifold.
Hopefully when I correct all of this my hard starting problem will be alleviated.
Thanks again!
Jack Christensen - K6ROW,
'76 Glenbrook/Clasco - "The Silver Bullet",
Sebastopol, CA
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| Re: Hard to Start [message #100459 is a reply to message #100133] |
Mon, 20 September 2010 19:24 |
kingd
Messages: 592
Registered: June 2004
Karma: 2
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Senior Member |
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And something called the "well plugs" could be leaking. Someone familiar with these can tell us if these cause the float bowl to empty, thus requiring more time or cranking to regill the float bowl.
DAVE KING
with a Carter AFB on an SOB
DAVE KING
lurker, wannabe
Toronto, Ontario, Canada
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| Re: [GMCnet] Hard to Start [message #100463 is a reply to message #100459] |
Mon, 20 September 2010 19:37 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Yes they do in fact leak the float bowl dry. I don't think that is the
problem in this case, because he said that he had an electric fuel pump that
he would turn on prior to attempting to start the engine. This should refill
the float bowl even if it were leaking down.
Jim Hupy
Salem, Or
78 Royale 403
On Mon, Sep 20, 2010 at 5:24 PM, Dave King <kingd@sympatico.ca> wrote:
>
>
> And something called the "well plugs" could be leaking. Someone familiar
> with these can tell us if these cause the float bowl to empty, thus
> requiring more time or cranking to regill the float bowl.
>
> DAVE KING
> with a Carter AFB on an SOB
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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