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Rebuilt quadrajet won't start.

black rust

black rust

1/2 ton status
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Jun 29, 2007
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Beecher, IL
Recently I rebuilt the q-jet on my k5. At first, I couldn't get it to start without a little shot of starter fluid. That stopped working after a couple times. I pulled the carb and removed the air horn to make sure I didn't put it back together wrong. Everything seemed okay, so I put it back together and put it on the truck. Started up fine first time, and every other time I tried that day. Went to start it today, and it went back to not starting. If I add a little starting fluid or hit the accelerator pump enough times, it will almost run, then die. Any ideas on what I did wrong?
 
You sure it's gto fuel in it? IE, fill the float bowl yourself, and start it? Or, at least checked to make sure the fuel pump is working?

I'd suspect the needle valve isn't hung off the float right. How about the idle mix screws? All the way in, then approx. two turns out? Choke?
 
dyeager535 said:
You sure it's gto fuel in it? IE, fill the float bowl yourself, and start it? Or, at least checked to make sure the fuel pump is working?

I'd suspect the needle valve isn't hung off the float right. How about the idle mix screws? All the way in, then approx. two turns out? Choke?
Click to expand...
Fuel pump works, float bowl fills itself. When I had it apart, I pushed the float down a couple time to make sure it wasn't stuck, maybe that did it? Idle mix screws are three turns out, I'm pretty sure that's what the adjustment settings said. Once I get it to run, it runs fine. Starting seems to be the problem. How would I check to make sure the needle valve is hung correctly?
 
Everything is fine except starting? Check the choke.
 
Is the accelerator pump working? Which hole on the linkage do you have the rod set on? If your rebuild kit was old, the seal on the actual pump could be shrunk up, and not sealing against its bore, making for a very weak shot of gas.
 
I don't think its the choke, because when it decides to do this, it won't run at all. I can shoot some starter fluid in or use the accelerator pump to get some fuel in it, but once that runs out it stops. Seems like the needle not hung correctly idea could be right. I thought it looked fine, so is there a way to verify this?
Accelerator pump is working, when ever I pump the pedal I get a shot of gas coming out, plus when I had it apart I tried pumping it and the fuel was flowing out. I have it on the outer hole, which I thought was right since I'm not at high altitude
 
the needle hangar (curved wire) should go thru 1 hole, then the end should be on the flat behind the hole.. Most people screw up by hanging it thru the one hole, and having the end go thru the hole next to that one... that can lead to the needle hanging up in the bore...
 
I think it did that wrong then, I'm pretty sure i just hung it off a tab sticking out on the float. Now that I think of it, I don't remember there being any holes, guess I wasn't paying good attention.
 
at the back of the fulcrum there should be 2 holes side by side, with a flat space behind them... thru 1 hole, then the tip just sits on the back flat section..
 
dyeager535 said:
You sure it's gto fuel in it? IE, fill the float bowl yourself, and start it? Or, at least checked to make sure the fuel pump is working?

I'd suspect the needle valve isn't hung off the float right. How about the idle mix screws? All the way in, then approx. two turns out? Choke?
Click to expand...
Having exact same problem and don't see holes
 
@86jimmyoregon did you rebuild the carb? Can you see fuel squirt out nozzles on the primary when you look down the choke and work the throttle, engine off. Your sig says 86 Jimmy I am guessing you have a computer carb?
How does it run after start up?
 
Only has electronic choke with hei ignition all stock. It fire on first crank then I guess u can say runs for 3 to 5 seconds then dies as if out fuel no spudder or anything. Choke starts to open up so choke is working. Last thing if you pump three time before starting is when it run for short time. Pumping thottle causes back fire
 
Sounds lean if backfire when working throttle, could be many things, choke adjustment off, low float level. Blocked passage, poor accelerator pump performance, fuel filter restriction, soft fuel hoses, bad screen in tank, and prob maybe afew other things I can't remember.
When did this symptom start? Have you been driving the truck daily before?
 
Wes Harden said:
Sounds lean if backfire when working throttle, could be many things, choke adjustment off, low float level. Blocked passage, poor accelerator pump performance, fuel filter restriction, soft fuel hoses, bad screen in tank, and prob maybe afew other things I can't remember.
When did this symptom start? Have you been driving the truck daily before?
Click to expand...
No truck had been sitting Few years have good fuel pressure I have saw carb on my 86 Jimmy this is on 85 g29 van with 305. I tried running with choke held open and would no start. Only starts after few pumps then turn key but dies and pumping accelerater does very little just stumbles then dies and thank you for taking time to help
 
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