Quadrajet carb
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From: Anacortes
Quadrajet carb
Not good with carbs but my last truck with a 300 started everytime no problem but this truck with a 390 has to be primed with the pedal and cranked awhile to be started after sitting like all night or an extended amount of time.
Also when I turn the key off it shudders and pops almost before finally turning off. I am really confused why this would be happening it does seem to be running rich though?
Also I don't know if it matters but the electric choke wasn't working so I just turned it enough to disengage it. Oh and new fuel pump due to another problem I thought I had.
Thanks for any help.
Also when I turn the key off it shudders and pops almost before finally turning off. I am really confused why this would be happening it does seem to be running rich though?
Also I don't know if it matters but the electric choke wasn't working so I just turned it enough to disengage it. Oh and new fuel pump due to another problem I thought I had.
Thanks for any help.
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From: Anacortes
That's really all of the symptoms I can think of for each situation.
The priming I assume is something float related where it's evaporating somehow.
And the sputtering I'm just lost, but yes this was my first place to throw up the question just wondering if anyone else had experienced it. Also I did search and found some related to the sputtering but I have checked most of those like dropping idle speed which had previously been too high.
The priming I assume is something float related where it's evaporating somehow.
And the sputtering I'm just lost, but yes this was my first place to throw up the question just wondering if anyone else had experienced it. Also I did search and found some related to the sputtering but I have checked most of those like dropping idle speed which had previously been too high.
Post Fiend
Joined: Jun 2003
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From: Black Hills of SD
You have to pump it because you have the choke propped open. Not good, you will dilute your oil with gas if you have to pump it a lot.
Run-on is generally caused from too high of idle speed, but not always.
Are you sure you have a Quadrajet? That's a General Motors carburetor.
Even if you turned the choke open, the fast idle might still be on the ramp. Why wouldn't you fix it right? Get the choke fixed and adjusted properly, and the idle speed functioning, then see if you still have the problems.
Run-on is generally caused from too high of idle speed, but not always.
Are you sure you have a Quadrajet? That's a General Motors carburetor.
Even if you turned the choke open, the fast idle might still be on the ramp. Why wouldn't you fix it right? Get the choke fixed and adjusted properly, and the idle speed functioning, then see if you still have the problems.
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From: Anacortes
You have to pump it because you have the choke propped open. Not good, you will dilute your oil with gas if you have to pump it a lot.
Run-on is generally caused from too high of idle speed, but not always.
Are you sure you have a Quadrajet? That's a General Motors carburetor.
Even if you turned the choke open, the fast idle might still be on the ramp. Why wouldn't you fix it right? Get the choke fixed and adjusted properly, and the idle speed functioning, then see if you still have the problems.
Run-on is generally caused from too high of idle speed, but not always.
Are you sure you have a Quadrajet? That's a General Motors carburetor.
Even if you turned the choke open, the fast idle might still be on the ramp. Why wouldn't you fix it right? Get the choke fixed and adjusted properly, and the idle speed functioning, then see if you still have the problems.
My idle used to be high but I turned down the fast idle screw enough to where only the low idle screw effects it.
I know it's a quadrjet because it says on there as well as GM on the choke.
So anyways the idle speed isn't the problem now but it smells rich and I think it is unburned fuel igniting with the compression or something.
Hotshot
Joined: Oct 2002
Posts: 18,488
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From: The Big, Oregon
Quadrajets are notorious for sticking floats, they will pour gas in the engine causing a severe rich condition and run-on.
As far as the choke, I believe it needs 12v with the key on. The coil power lead cannot provide the needed current and the truck might not even run then. I don't know what you mean by high idle and low idle screws, there is only idle speed and mixture adjustment. At the front of the carb there are two screws at about 11 and 1 o'clock, just above the base gasket. Those are the mixture screws. They should both be adjusted the same, a good starting point is usually to tighten them to just snug, and then back out two turns. Do not crank them in tight or it will damage the carb. There is also a screw on the linkage to set the idle speed. The idle mixture and idle speed screws as well as ignition timing and vacuum affect the idle speed, so I'd recommend at least watching some carb adjustment videos on youtube or have someone who knows carbs show you how to set it.
As far as the choke, I believe it needs 12v with the key on. The coil power lead cannot provide the needed current and the truck might not even run then. I don't know what you mean by high idle and low idle screws, there is only idle speed and mixture adjustment. At the front of the carb there are two screws at about 11 and 1 o'clock, just above the base gasket. Those are the mixture screws. They should both be adjusted the same, a good starting point is usually to tighten them to just snug, and then back out two turns. Do not crank them in tight or it will damage the carb. There is also a screw on the linkage to set the idle speed. The idle mixture and idle speed screws as well as ignition timing and vacuum affect the idle speed, so I'd recommend at least watching some carb adjustment videos on youtube or have someone who knows carbs show you how to set it.
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From: Anacortes
On this carb there is an idle speed for choke and disengaged choke by the linkage.
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Cargo Master
Joined: Oct 2011
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From: Kenner,La.
QJET
Cali, It appears that the float chamber plugs are leaking. When they leak the float chamber drains into the manifold. They are located under the float bowl and can only be checked by removing the throttle body. They have a reputation for leaking, they can be resealed with epoxy. Get the model # from the float body to get the correct kit to rebuild it from a NAPA store.
Good luck , Kenny
Good luck , Kenny
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Post Fiend
Joined: Jun 2003
Posts: 8,209
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From: Black Hills of SD
Quadrajets are notorious for sticking floats, they will pour gas in the engine causing a severe rich condition and run-on.
As far as the choke, I believe it needs 12v with the key on. The coil power lead cannot provide the needed current and the truck might not even run then. I don't know what you mean by high idle and low idle screws, there is only idle speed and mixture adjustment. At the front of the carb there are two screws at about 11 and 1 o'clock, just above the base gasket. Those are the mixture screws. They should both be adjusted the same, a good starting point is usually to tighten them to just snug, and then back out two turns. Do not crank them in tight or it will damage the carb. There is also a screw on the linkage to set the idle speed. The idle mixture and idle speed screws as well as ignition timing and vacuum affect the idle speed, so I'd recommend at least watching some carb adjustment videos on youtube or have someone who knows carbs show you how to set it.
As far as the choke, I believe it needs 12v with the key on. The coil power lead cannot provide the needed current and the truck might not even run then. I don't know what you mean by high idle and low idle screws, there is only idle speed and mixture adjustment. At the front of the carb there are two screws at about 11 and 1 o'clock, just above the base gasket. Those are the mixture screws. They should both be adjusted the same, a good starting point is usually to tighten them to just snug, and then back out two turns. Do not crank them in tight or it will damage the carb. There is also a screw on the linkage to set the idle speed. The idle mixture and idle speed screws as well as ignition timing and vacuum affect the idle speed, so I'd recommend at least watching some carb adjustment videos on youtube or have someone who knows carbs show you how to set it.
You need to get that all working like it should be. Most advice you will get on forums, doesn't pertain to jerry-rigged engine management systems but to serving them as they were intended to operate.
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From: Anacortes
So I guess I wasn't very clear but it's a quadrajet from a GM with electric choke. Also I measured voltage but don't remember the volts and therefore disengaged it because it wasn't turning off on its own. I backed the fast idle out enough that I could adjust only the linkage side idle. I also just recently noticed t wasn't working that's why I haven't fixed it yet.
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From: Anacortes
So I have another question then, why does the fuel just happen to go past the rings is it simply because the float isn't workin and the fuel has to go somewhere or I just have piston rings that are old and need to be replaced soon.
Cargo Master
Joined: Feb 2006
Posts: 3,008
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From: North Pole, Alaska
You are dumping raw fuel into the intake manifold with your junk-jet which ends up into the cumbustion chamber, and then washes the oil off the cylinder walls, finally ending up in the oilpan. Gas is a solvent which dilutes and ruins the lubricating qualities of the oil. Eventually you will have metal to metal contact of the rings and bearings, and then won't have an engine left to use. It is that simple.