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Q-jet Carb ?

Maybe the "sock" filter in the tank is clogged with dirt or water????.Have you tried blowing compressed air back into the tank from under the hood--may be some crap stuck in a steel line to the tank.I had one truck at work that drove is nuts for days--finally changed all the metal lines,rubber hoses,and fuel pump and the sock--that cured it!.I was curious to find out what it was--my co-worker put the air hose in the old metal line--and it was nearly airtight in one spot--we pushed a small phillips screwdriver through it and a couple of yellow jacket wasps came out! /forums/images/graemlins/eek.gif /forums/images/graemlins/rotfl.gif
 
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Maybe the "sock" filter in the tank is clogged with dirt or water????.

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5this is what I am thinking...
 
EST is the system that used this electrical controlled Q jet.

at least in the 80-mid 80s years anyways, GM affixed a plastic EST electronic spark control timing badge on the tailgate of the EST equipped rigs,

if its already ben converted to non EST setup then you cant be using an ESt controlled carb, it wil dump fuel in by default just like they do when are unplugged,. swap to 75-79 or older HEI and to a Q jet minus any ESt controls in it,


good luck
 
EST has nothing to do with carb control on non-CCC rigs. He already stated it is not a CCC carb.

EST is a seperate system on most trucks. If the truck is CCC, EST is an integral part, not standalone like the EST only rigs, which used "standard" carbs, like his. (whether or not it is EST)

Good point though, this could be something EST related if that is on this truck.

On a side note for anyone reading this, was EST used on 350 trucks? I *think* no, compression was so low there was no need.
 
OK here is a pic of the sending unit. I think I have the hoses labeled correctly. The screen filter was some what OK I could blow thru the hose and the tank was clean. . My qusetion is about the hose running from the charcoal canister to the sending unit. If I blow into the sending unit no air will pass thru it. Is this normal or plugged?

DCP_2917_copy.jpg
 
I would think it should be an 'open" connection, but I've never tested it.

Evap should certainly not be the cause of your problem, even if that line was plugged. Your cap will vent. It is essentially a one way system, vapors in tank make their way to the cannister, which is purged into the air cleaner.
 
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EST is the system that used this electrical controlled Q jet.

at least in the 80-mid 80s years anyways, GM affixed a plastic EST electronic spark control timing badge on the tailgate of the EST equipped rigs,

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Actually no this is not correct (as Dorian already pointed out)

My rig came from the factory with ESC, but no badges (that was earlier on, in the 82 neighborhood) and no wires running to the carb other than the electric choke.

I'll 2nd the fact that ESC has nothing to do with the carb. /forums/images/graemlins/thumb.gif
 
I had a problem when I first had my truck where it would die , or just not run well if it ran . Happened every time I thought it was running good for a long time . After removing the top off the original quadrajet it dawned on me. I kept finding little black flecks and such in the float bowl. These were lodging into the jets. I decided it was the vapor cannister or air cleaner charcoal filter thingy , seeing as how all the vacuum hoses were routed . Took off the charcoal flame arrestor looking thingy from air cleaner, Replaced my 83 vapor cannister with a 1978 one and got rid of some of the vacuum hoses as well . Carb never had a problem again , besides the throttle shafts leaking , still have it in the box my new Quadrajet came in ( only replaced for throttle shafts and peace of mind ). I would never off thought that at all except by trial and error. /forums/images/graemlins/thinking.gif
 
/forums/images/graemlins/smile.gifclogged fuel line between the fuel pump and the tank /forums/images/graemlins/smile.gif

Thanks to everyone for all the suggestion that were given.
 
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clogged fuel line between the fuel pump and the tank

[/ QUOTE ] I had that same problem before. Had me scratching my head for awhile. Who would figure that a 3/8 hard line could get plugged /forums/images/graemlins/dunno.gif
 
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Fuel metal line...

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I'm asking what was in the line that was plugging it.
 
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What the heck was in it??

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really don't know, I blew it out with air. At first you could feel the presure build and then it let go.
 
Probably those damm pesky yellow jacket wasps again! /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/grin.gif I still dont know how they got past the "sock" in the gas tank in the truck I had the same problem with--one for the "unsolved mysteries"file I guess! /forums/images/graemlins/dunno.gif
 
Well it ran alright for a while now it is back to doing the same thing. I blew the lines out again drove it all day yesterday and it ran great, just before I got home it started again. Looks like I have to take the Dodge Aires wagon to the coast this weekend /forums/images/graemlins/tongue.gif and start checking stuff when I get home. /forums/images/graemlins/confused.gif /forums/images/graemlins/angryfire.gif /forums/images/graemlins/crazy.gif
 
You might have to pull the tank out,and remove the sending unit and fuel pump(assuming its EFI)and replace the sock filter--its about 10 or 15 bucks.It could be water in the fuel,the sock wont let water pass through it,after enough water builds up on the outside of the sock it wont allow any gas to go through,until you blow it out again.You might want to put a new fuel pump in while your in there,its not fun pulling a tank twice.I also have seen a peice of rubber fuel line that looks like an inchworm on the frame near the tank on the passenger side that joins the two sections of metal fuel line,near the right rear tire on the inside of the frame rail,get all separated inside and act like a check valve,blocking fuel flow--I replaced a fuel pump and many other things on a suburban before I found that rubber hose was collapsing,looked ok on the outside.Why GM puts that hose there is another one for the unsolved mysteries dept.Maybe to drive whoever owns it nuts after 10 years or so??.Hope you have a good 4th,despite the fuel problems!. /forums/images/graemlins/grin.gif
 
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