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post #1 of (permalink) Old 11-03-2002, 07:12 PM Thread Starter
 
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Some Quadrajet carb issues (I think)

Hi guys, I am trying to fix a 87 Camaro with a 5.7 and a Quadrajet carb, all stock. I figured since I would post here than trying to find a new list to join. Basically, the car ran normal, sat for 2 days in the driveway when started agian, started fine, but had a little hesitation on take off, soon after, about 3 miles on a 35MPH street, it finished crapping, it would not run at part throttle, and would die at full throttle. It would run about 10MPH at about half throttle, seeming like it was running on 4 cylinders. After letting it sit over night, it started and dies 3 times, no it wont do anything......just barely stumble on a few cylinders. Gave it a good look over today and all seems fine. Spark is good, and fuel is plentiful. We sprayed starting fluid down the carb and that did not make much difference. The car has been sitting for a time (6 months, its my brother in laws car) before I got to take a look at it.

It is a uninjected 87 Fbody with a Quadrajet carb with a few electical connections. There is a green unit on the top that clicks like the old diaphram style electirc fuel pumps. I pulled the plugs, a little oily, but nothing out of normal.

Any ideas I can try here. He wants to fix the car, but leave it stock. I told him to put a Holley on it, but frowned on the idea!!

Nathan
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post #2 of (permalink) Old 11-03-2002, 08:46 PM
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Re: Some Quadrajet carb issues (I think)

How do you know the fuel is plentiful? Did you crack the line at the filter?

Is the filter clean?

Is the choke opening?

If you stare down the throat you should be able to see fuel going down the barrels while running. Do you?

While it's running, open the throttle to the point where it stumbles and won't run. Then move the accelerator pump. If it doesn't squirt gas or squirts very little then it's a fuel problem. You should be able to get 4-6 full squirts out of the accelerator pump.

What color are the spark plugs? Are they light and blistered or dark and slimey? If the spark plugs are chocolate colored (anywhere from milk chocolate to light milk chocolate) then it's not likely that fuel is a problem.
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post #3 of (permalink) Old 11-03-2002, 08:55 PM Thread Starter
 
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Re: Some Quadrajet carb issues (I think)

Yes we chaned the filter and turned the car on to see if fuel was flowing, plus we plenty of accel shot.

The car is cold, and the choke is closed. I can manually move it, and holding the throttle wide open for a flood clear has no affect

The car does not run, only stumbles on a few cylinders irregularly while cranking.

The plugs are a little black, but have no problem fireing by ground near the header.

I have no exp. with a Qjet carbs, just Holleys.

As noted atop, wont run on accel pump, and stating fluid has no real affect. But we are getting spark, nice blue spark. Cranking on number one is 140psi. Full 12 volts to the coil. I want to slap a Holley on there, but the Bother in law does not want me too.

Any other ides?

Nathan
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post #4 of (permalink) Old 11-03-2002, 09:12 PM
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Re: Some Quadrajet carb issues (I think)

I take it that it has an electric fuel pump?

Did you try what I said to do in my previous post?

OK, but is fuel getting into the carburetor? Is the float bowl getting fuel? The float bowl can be checked with the accelerator pump. 4-6 pumps will drain the float bowl. If the float bowl never gets enough fuel then the primaries won't get enough fuel to feed the motor.

Is it electric choke or manual choke? If the choke is staying fully closed then it won't run. It needs 1/16" - 3/16" to run. The choke, if electric, should slowly open to a point. To get it to open all the way you'll need to use the throttle to let the arm drop and the butterfly fling open. If you lay down and look at how it works it's not rocket science and you can figure out what's supposed to happen.

What does "a little black" mean to you in spark plug terms? They're supposed to be milk chocolate. If they're dark then it's rich. If they're light/white and/or blistered then it's lean.

If they're dark or wet, then fuel isn't the problem. It's either spark or air. Air can be solved by keeping the choke open.

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post #5 of (permalink) Old 11-04-2002, 06:58 AM Thread Starter
 
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Re: Some Quadrajet carb issues (I think)

I caanot confirm electric or manual pump, but in the hour I spent trying to get the car to run, I always had an accel pump, so I am believing that the fuel in the carb is not an issue, but I will look into it.

I have been tuning small block for quite some time, first by the choc mild method, then finally upgraded to a O2 sesnor and a DVMeter. When I say they are black, they seem to have just a coating of oil on them. Plug is not corroded, or other wise deterioated, looks new just a coating of slight oil, nothing I would think to be concerned about, gap was good at 30 thou, and the car only has a 55,000 miles.
I know all about electric chokes, as you say, very easy to work with, but I cannot get the car running. It is closed to get the car started, and I held the it open quite a bit. It wants to start from time to time, but only fires while cranking. I looked down the throat to see if fuel was lewaking out the boosters, but nothing.

I wonder if something is clogging the carb? They changed the filter 6 months ago, so I have no clue what the original looks like

I may go more mechanical, and look at the cam timeing and so on.......And look a little deeper into the distriber.

Ninwa
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post #6 of (permalink) Old 11-04-2002, 01:54 PM
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Re: Some Quadrajet carb issues (I think)

How old is the fuel? Now days, if the fuel sits for any length of time, it will go bad and cause the same problems that you describe. It seperates its properties and will not ignight.
You probably have a mechanical fuel pump located on the passenger side of the engine block. If you can get a hold of a fuel pressure gauge, you can hook it up at the carburetor and see if the pressure is fine.
When were the plugs changed? they might look fine, but they could be bad internally.
Have you checked the Cap and Rotor? make sure they are clean. After sitting for 6 months, they could have dirt in them and causing arcs within the cap.
Are the Plug Wires ok? rodents love to chew on silicone wires. Check to see if there are any cuts in them.

Just a few thoughts and things to check.
Tom
post #7 of (permalink) Old 11-04-2002, 04:35 PM
 
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Re: Some Quadrajet carb issues (I think)

Here is a shot in the dark.. you said it would fire while cranking... take the module out from underneath the dist rotor and have it checked a local part store.

It sounds way off, but I have seen this problem in the past..
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post #8 of (permalink) Old 11-04-2002, 09:14 PM Thread Starter
 
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Re: Some Quadrajet carb issues (I think)

It does not seem that far off........these whole symptoms happend for the same reason why the car was parked. This happened while it was being daily driven, he has just come to after 6 months to get it running.

Nathan
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post #9 of (permalink) Old 11-05-2002, 07:24 PM
 
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Re: Some Quadrajet carb issues (I think)

I checked back at some old recalls for that year F body. Seems there was a recall on the coil and module for that year. You may want to check to see if the recall has been completed. If not, you should be able to get the parts from the dealer or a local parts house.
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