FERL 73

I started the engine today and it ran about 30 seconds and died. Then it wouldn't start. I pulled the air cleaner and gas was all over the intake. I dried everything and tried to start it again with the air cleaner off and after cranking a few times gas starts spewing out of the tubes on top of the carb. I disconnected the fuel line and re-routed it temporarily to a gas can and was able to start the car with the fuel remaining in the carb. I reconnected the fuel line and it started right up but again the gas started spewing out of the tubes on top of the carb and flooded it out again. Is this a stuck float?

Larry B.

It is either a stuck float,or inlet needle. Floats can also absord fuel and sink.

FERL 73

Thanks Sivervetteman for the response. Well, I pulled the carb and removed the top. Nothing appeared to be stuck or malfunctioning. I removed the float/needle & power piston/primaries. Nothing seemed wrong. I put it back together and it worked like it always did. Fired right up and no more spewing of gas. I suppose I now have new questions. I reused the same gasket for the air horn beacause I didn't have a spare lying around. Is this OK? I did have a spare for the intake.
I don't really know what caused the problem or what fixed it. Is this going to keep happening?

lars

Alan -
I just caught your post that you solved the problem. You most likely had a hung up float, and you fixed it by simply popping the top off the carb and screwing around with it. The gaskets can be safely re-used indefinitely until they tear or get damaged - no problem using the old one. Anyway, here is the answer I posted before I saw you had the problem fixed - maybe someone else will get some use out of it:

Alan -
If there is fuel pouring all over, you have a float level control problem. This can be caused by a few things:
1. Piece of dirt stuck in the needle/seat area
2. Float hung up and stuck
3. Float level incorrectly set
4. Float fuel-logged and sunk

Best thing to do is pop the top off the carb and see what's going on. Here is a basic procedure for you:

To pop the top off a Q-Jet, proceed as follows:

1. Remove the air cleaner stud.
2. Using a hammer and a small pin punch or a small finish nail, tap the roll pin holding the accelerator pump lever to the top of the carb in towards the choke horn wall. Don't tap the roll pin all the way up against the wall - leave just a slight gap so you can later get a screwdriver blade in behind it to pry it back again. Remove the accel pump lever.
3. Remove the single screw holding the secondary rod hanger to the top of the carb and remove the hanger with the secondary rods.
4. If you have a later-model Q-Jet with a choke vacuum break diaphragm that is attached to the passsenger side of the carb with two screws up high, remove the two screws and remove the vacuum break and its connecting rod. If your vacuum break is pressed into a bracket that is not attached with 2 screws up high, leave it alone.
5. Remove the choke connecting rod. There are 2 types: One type has a clip holding it to the choke lever. Remove the clip, disengage the rod from the upper lever, then twist/rotate the rod to disengage it from the lower lever inside the carb. Later model carbs have a single screw holding the upper lever to the choke shaft. On this type, remove the screw, remove the lever, and remove the choke rod by twisting/rotating it to release it from the lower lever inside the carb.
6. Remove the (2) 1/2" head bolts at the front of the carb.
7. Remove the 9 top attach screws: Two long screws in the very back; a screw on either side of the secondary airvalves; two screws just forward of the secondary airvalves; two screws just inside the choke air horn right at each primary discharge nozzle, and a single screw center front. If the carb has the stock screws in it, the two screws inside the air horn are designed to be too big to drop down into the intake manifold. But many aftermerket screws can, in fact, drop through the carb and go into the intake. Once you have loosned these two screws, use a pair of needle nosed pliers to carefully lift them out and make sure they don't drop.
8. Lift the top of the carb straight up until it clears the accelerator pump and until the air bleed tubes clear the gasket. If you have a non-removable vacuum break diaphragm, fowl the top over to the side to disengage the secondary airvalve rod.
9. Remove the gasket by carefully freeing it from the power piston/primary metering rod hanger.
10. Remove the accelerator pump.
11. Remove the power piston/primary metering rod hanger by pushing it down against its spring pressure and "flicking" it off your fingernail so it pops up. A couple of flicks will disengage the locking collar from the casting, and the assembly can be removed.
12. Remove the phenolic float bowl filler.
13. Remove the float and needle as an assembly.
14. Remove the main jets.

The rods and the jets are stamped with their sizes.

Only trick for re-assembly:

1. When installing the power piston, take care to fish around until the rods drop down into the jets and the power piston works smoothly. Gently push the piston nylon locking collar back into the carb casting. I've seen people not get the rods into the jets, and simply smash the top of the carb down onto the piston/rod assembly. Obviously, this will bend the rods.

Once you have the top back on, installing the choke linkage rod is considered the only "tricky" part. There is a short lever arm down inside the carb, and this arm has a hole in its end. This arm is very easy to see when you have the top off the carb, so I recommend that novices take a look at it and its orientation/function while they have the top off the carb. With the top off, take the choke rod and practice installing/engaging it in this lower lever until you get the knack of rotating the rod slightly to engage it in the hole in the lever.

Once you have the top back on (taking care not to overtighten screws and bolts), activate the choke linkage on the outside of the carb to move this lever arm to its furthest "up" position. You can just barely see it if you look down the carb. Now, insert the choke rod down into the carb, with the rod rotated slightly. Engage the hole in the lever arm at this angle, and once you've hooked the arm, rotate the rod to fully engage it.

Install the accelerator pump lever to the top of the carb. Insert a finish nail or a small pin punch through the roll pin hole to assure that it's aligned, and then use a small screwdriver to pry the roll pin back through the lever.

Install the secondary metering rods with the hanger.

NOTE: If you're going to be doing several jet changes, you do not need to attach the choke linkage rod to run the car. Leave the rod off until you're complete.



[Modified by lars, 9:35 PM 5/19/2002]

Rockn-Roll

Thanks for being around Lars. :)

FERL 73

Thanks Lars. Looks like I did it the hard way. Is it OK to reuse the top gasket or do I need to get another one and do this again?

73 LS-4

Lars said it was ok to reuse the old one as long as it's in good shape, but if your like me you'll feel better with a new one if your not in a hurry. Glad to hear you got it back together and running :D

:cheers:
Pat Kunz

clem zahrobsky

do not hook the float clip into the holes in the metal float arm,as this will cause flooding because it will cause the needle to bind in the seat body. the float clip just hooks over the float arm. :chevy

FERL 73

Pat, I guess I should read ALL the words

Clem, Fortunately I have the idoitproof float "no holes". I guess I could disprove the foolproof theory and drill one. I appreciate the heads up.

On a second note, I started wondering about all that gas that was spewing out into the top of the carb and decided to change the oil. I'm glad I did! It sure smelled like gas.

clem zahrobsky

i have never seen a genuine GM nitrophyl Q jet float without the holes in the arms where you could hook the needle hook by mistake. you are not using a brass float are you as these have a different bouyancy than the GM float and takes a difference float setting. :chevy

FERL 73

Clem, Yes it is a brass float. I had this carb rebuilt about 2 years ago (2000 miles) by a guy that the local parts/machine shop recommended. I felt confident that the guy knew what he was doing. I'm assuming the float was set correctly but I don't know that for sure. When I took the top off and removed the components I didn't reset or adjust anything. I didn't want to hose it up. I recently bought two 7042208's and the book by Roe. I'm trying to learn a bit about Qjets without hosing up the the one on the engine now. I am in the process of rebuilding one of the 2 carbs and haven't started to put it back together yet. I'm in no hurry and am taking it slow. I bought the kit and float tonight for my project carb and the float I bought is the non-brass type. It does have the holes.

lars

FERL -
I've never had any luck with those brass floats - you do not know what the float level really is with one of those things. Always use the NitroFills to asssure proper fuel control. If you can't get the GM ones, the NAPA NitroFills are exact reproductions and they will float the same (I've actually tested them). As Clem says, be sure to hook the needle clip around the rear, rounded side of the float arm and not through one of the holes - GM actually published a Service Bulletin about this issue.