Rebuilt 72 4 BBL Q-Jet leaking bad

Just had a rebuilt Q-Jet installed on my 71 Skylark 350. Left the shop and everything was fine until I went to restart it after I got home. Gas is coming up and out through eveything while car is running. Did the float get stuck?? What gives?? Can't get the car back to the shop until Monday at which point I'll probaly have it towed since she won't stay running. Was hoping in the meantime I can find out what happened and correct it. Same guy who did the rebuild did the install. She was purring like a kitten and then all went down the tubes!!!!:af:

 

Yes, the float is probably stuck or there is some trash preventing the seat from sealing so gas continues to flow.

Try tapping the front area of the carb, above the fuel inlet with a wrench. Don't tap very hard, and try it with it started so fuel is flowing. It might clear itself up unless the float is set incorrectly.

Check and replace your fuel filter, or add one if you don't have it in there.

 

Gonna try that later today if I can get her running. Fuel filters and such were changed at time of install!

 

I seem to have this problem whenever I change fuel filters. I've heard that new filters have loose paper fibers that get stuck in between the needle and seat. It goes away quickly.

 

Gonna go give it a try. Thanks for the info guys!ray:

 

I tried! Still peeing away! Even changed the filter! Thought I had it fixed as all was working fine in the garage. Then I went for a ride and after after she heated up I stalled, got out, and saw the gas!! AGAIN :blast:

 

Any other ideas????

 

pull the top and check the float setting. That's about the only thing you can do at this point.
Only other possibility is too high fuel pressure.

 

Question?

If the float was stuck or its setting was bad wouldn't it flood all the time? It starts out fine and I even let the car run (playing with the idle) for about 20 minutes with no problem. Then as soon as go for a ride she ends up running like crap and stalls out while peeing fuel. Things lasted a little longer when I tapped (smacked is more like it) on the carb while running which helped out at first. This is what made me think the float was just sticking. I should say that when I first picked the car up from the shop she went 40 miles with me playing around and I had no problem. It all started after I got home and she sat for a bit. As suggested I changed the filter and while I had things apart I sprayed gum-out into the line port of the carb. I then put things back, started he up and she was bleeding gas within a minute this time around. Didn't change the fuel pump as I was told it was fine!
Talk about frustration!!!!:rant:

 

What about the spring that holds the needle to the float? Is it installed correctly? Has the spring behind the filter been installed, or is it binding? Is the seat loose? Is the fulcrum for the float pointing the right way? Some thoughts I have had, hope you fix the problem.
- Gabe.

 

It sounds like you have dirt/debris getting caught up in the needle and seat. You need to take carb apart and clean the castings. The fuel inlet threads are probably deteriorating, so pay special attention there.

 

If you don't want to take the carb apart you can try pinching off the fuel line and letting it run out of gas. That will often clear a piece stuck in the needle and seat......

 

Was told that the accelerator pump was leaking. Having the whole carb taken apart and redone!

 

that's interesting. Keep us informed on that.

 

Something to consider here is the condition of the float itself. If the fuel has attacked the float itself, the result will be that the float will perform perfectly when dry, but, as it soaks up fuel, it will get heavy. It will gradually reach a point where it will sink into the fuel instead of floating on top of it. This may have been caused by the handling of the float improperly, or that the surface simply deteriorated. Either way, it will require replacement of the float. That is why my carb rebuilds ALL get new floats when completed. Ray

 

Good point....and a brass float would be a good idea rather than the nitrophyl.

 

I'm lost. Car was brought back after she flooded over. Was told problem didn't surface when checked. I was then told the vacuum advance disc on the carb split and was probably my cause for concern and all was OK. Picked the car up after the shop closed and she flooded in less than 3 miles after leaving. Sent her back and was told she might have a float problem as nothing could be found to duplicate my problem. Got her back today and started having an idle problem. Checked the timing, spark and even adjusted the carb but the idle refuses to hold steady. What gives??? Carb is no longer leaking but she just doesn't want to settle in. Is the re-builder missing something??? Nice guy who means well but doesn't feel or see what I see. Lots of $$ into this aggravating dilemma!

 

Probably a piece of dirt/debris that is migrating around the inside of the carb. I'd pull it off and clean every passage out.

 

Check the float...sometimes the develop a "pin hole" and will not float.:bglasses:

 

It sounds like the float is either soaking up gas (making it heavy and causing it to sit lower in the bowl, making the fuel level rise) or the float is sticking. There's several different shapes of plastic floats and even brass floats can develop pinholes that cause them to be heavy in the bowl.

Some Q-Jets have damping springs too, and it may even be possible that the inlet valve is sticking, causing the float to sit low in the bowl (once again, increasing fuel level in the bowl)

If a new inlet valve was installed that has a different seat facing, then the float will probably have to have it's level adjusted too.

On a side note, when you get a chance buy a copy of "Rochester Carburetors" by Doug Roe, originally printed in 1981. The ISBN is 0-89586-301-4

I had learned so much from reading this book that I had to thank the man, and I actually managed to find his phone number. Unfortunately his wife informed me that he had passed away but she was happy to hear that someone was still benefiting from his book. This book is the reason I'll never use anything but a Q-Jet on a car that I can bolt a carburetor to.