Runs out of fuel…

75gmck25

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First - well plug leaks were common on earlier Quadrajets, but if this is an 80's vintage Quadrajet it is unlikely to have well plug leaks. Its one problem GM figured how to fix.

If you have hard line all the way from the fuel pump to the carburetor its a little harder to splice in a T for fuel pump pressure. My truck had a short section of rubber line where they spliced in the filter near the carburetor and I was able to use that point to add a T fitting and connect it to a pressure gauge. Then I added a long line for the gauge, ran it up to the windshield, and taped the gauge to the windshield. Not elegant, but it gave me fuel pressure readings under all conditions.

I also agree that it may be something with the float level or the needle. However, usually an improperly adjusted float only runs out of fuel under extreme conditions and not just during a run around the block. The needle has to be installed correctly in the hangar and the float adjusted properly.

Also check the transfer slot exposure in the primary to make sure it is close to a square shape at curb idle. Leave it there and adjust the idle mixture for best idle. If you get the slot exposure way out of whack you may be able to get the truck to run okay by adjusting the idle mixture. However, once you hit the throttle it goes so lean during the transition that the truck stalls. This usually happens when you drop off on the throttle so it goes back to idle (like at a stop sign), and then hit the throttle to accelerate again - which stalls the engine.

Also verify your base timing, and then try increasing it to about 15-16 degrees BTDC. Also check to see you get about 18-20 degrees more out of the mechanical advance. The stock engine is very low compression so it will usually handle a lot more advance, and this will make it run better in normal driving.
 

BJedi76

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Reinstalled carb, tuned it to 750 rpm @ idle (warm)

Tuned the air screws & reset idle to 750 RPM.

Idles like a dream…
revs like a beast…

test drove it…
in first gear it romps and races like a monster, but as soon as it shifts into second, it dies & won’t restart.

if I prime the air filter, it will start for a few seconds and die. After five times of doing this, it still won’t stay running.
 
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BJedi76

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Ok
 
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BJedi76

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Thank you…
 
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Ricko1966

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I'm a professional and I will tell you 4'btdc is not necessarily correct. But that's not what's causing your problem.
 

Rusty Nail

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I bet good money the vehicle information label calls for 0° but it's irrevelant. 0,4,8 - whatever. Depends where you are really.

So look if it's not the fuel filter spring then I'm lookin at pulling wires loose at the distributor or carb ... bad module ...theres not a ton of options.... It's only gonna be so many certain things.

We coulda had it fixed already - but there's no pictures. :nono:
 

BJedi76

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Ok
 
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Ricko1966

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What pictures do you want?

nobody has suggested pictures until now.

That was a joke. Did this truck run right before you started messing with it?
 

BJedi76

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BJedi76

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I have been “messing” with it for years.

I rebuilt the carburetor, installed a new distributor, installed a new starter, and replaced the fuel pump, pretty much at the same time.

when I wasn’t getting fuel, I took it to a shop. They replace the brand new fuel pump with another new one. I drove it home. A couple days later, it wouldn’t start no matter what I did. I took it back to the mechanics and they replaced the fuel pump again saying the new fuel pump was bad.

I drove it home. I drove it several times (over 20 miles).

It sat for a few days and then wouldn’t start. I primed the air cleaner and it started. When I tried to drive to the store, it would only let me use up to 1/4 throttle or it would die. I got it home babying the throttle.

…and here we are.
 

BJedi76

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The engine bay was also disaster from the previous owner, so I replaced many of the wires.
 

BJedi76

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Paladin

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Your move.

?????......a challenge? If so, accepted, but I do need to know what game you want to play!! Chess, Checkers, Backgammon? I merely was stating my opinion, admittedly somewhat sarcastically, of the world renowned piece of **** commonly referred to as the Q-Jet. I am not a Self Proclaimed "Professional" as many on here are, just merely a guy with a big ass square with a big ass motor sporting a Holley Carb which hasn't given me a hiccup in over 11 years! Seems those with Q-Jets spend more time trying to fix problems than driving their vehicle. I enjoy driving mine instead of constantly fixing carb problems!!! Always brings a grin when I see a new thread involving a Q-Jet and all the wah, wah, wah. So when the next thread pops up, which it will, I will have another smart ass remark to make concerning the Q-Jet. Such is Life!!!!
 

Ricko1966

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Okay now test fuel pressure and volume. Now that's an ESC truck with a mystery distributor, hooked up wrong so chance are real good that 4degrees isn't even close, but still won't make it die shifting to second.
 

BJedi76

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I also installed a new oil pressure sending unit, temperature sending unit, junction block, starter, battery cables, all the vacuum lines, in tank fuel sending unit, in-line fuel filter , and a new steel fuel line with the fuel pump, water pump, power steering pump and lines, radiator hoses, transmission filter, heavy duty torque converter cover and stabilizer bars, & T-case shifter linkage.
 

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