[crm318]

I was cruising around today in my 70 GTO when at the end of my drive, the car died at a stop sign. I feathered it to life and got it home where it died in the driveway. I popped the air cleaner off and nothing looked amiss. I heard a faint ticking sound (car off). The venturis were a bit wet. The stock fuel line was hot at the carb, but not at the fuel pump. I blipped the throttle and fuel exploded out of the vent tube! I mean sprayed the bottom of the hood! In all of my years of wrenching and quadrajet building, I have never seen pressure build up in a quad and spray out. Is that a float issue? What do yall think? It's fairly hot outside today, Engine temp was 190.

[Qball]

Maybe your float sank partially and is allowing too much fuel in the bowl?


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[crm318]

Would that allow the carb to pressurize?

[400 Lemans]

Is there alot of pressure when you take the gas cap off? May not be venting.

[Sirrotica]

More than likely a piece of trash was stuck between the needle and seat. I have seen where a needle is stuck fast in the seat. With an electric pusher pump it may have finally moved, and allowed a stream of pressurized fuel to enter the bowl. It may have then stuck open then so the float wasn't able to overcome the stuck needle valve. Yes, it is not a common occurrence, but needles stuck closed do occasionally happen.

Maybe take the top off and look for foreign objects in the float bowl to verify, it did, or didn't happen.

I have occasionally seen a needle stuck closed with trash in the seat, no gas getting to the float bowl. Fuel at the line, but no fuel entering the bowl.

[crm318]

Took the gas cap off, no pressure. I'm about to take the carb off and tear it down. I'll let you know what I find.

[25stevem]

When you get it all back together and before you bolt it on flip the carb upside down and blow into the fuel inlet fitting.

You should not hear any air getting into the fuel Bowl, if you do it will still flood out on you.

[crm318]

Tore the carb down and didn't see anything out of the ordinary. Very clean, no trash in the needle, seat or filter. It was acting like it was flooding, only started with the pedal on the floor. It does have a new fuel pump. Doesn't explain the pressurizing.

["QUICK-SILVER"]

That plastic splash well full of gas? If so, it was definately flooding.

May need to check fuel pressure with that new pump...

Clay

[242177P]

Iron intake. Hot(?) fuel line. Where's that heat coming from? Exhaust crossover?
Unfortunately, a *new* fuel pump isn't exactly reassuring nowadays. If excessive
pressure is sent to the carb, the needle/seat cannot do their job. Pressure test?

[carbking]

Originally Posted by crm318

Tore the carb down and didn't see anything out of the ordinary. Very clean, no trash in the needle, seat or filter. It was acting like it was flooding, only started with the pedal on the floor. It does have a new fuel pump. Doesn't explain the pressurizing.

New fuel pump?

Check the fuel pressure coming into the carburetor.

Jon.

[crm318]

Yes, the black "top hat" looking piece was full to the brim. How could I test the pressure with a hard fuel line? Like I said, the line was hot where it makes up to the brass filter housing. It was cool everywhere else. It isn't in contact with anything.

[abefromen]

unrelated.......your alternator looks to be clocked wrong?

[Joe's Garage]

I can't quite tell, but it looks like a washer and screw stuck under one of the alternator case bolts (?).

And, yes, you should re-clock your alternator and get the plug and main terminal up away from your intake manifold. Easier to disconnect and less chance of shorting it out accidentally.

Also, buy the little plastic cover for the main terminal that snaps over it and protects the terminal from being shorted. Like the one in the 2nd pic.

I'll predict that you will find that the pump is making excessive pressure and overpowering your needle and seat slightly.

To check the pump output pressure, you will need to temporarily cobble together a fuel line from the fuel pump to the carb with a 'T' fitting in it to connect a pressure gauge. We've done this with rubber fuel line and brass fittings before.

Good luck!

[crm318]

I was able to cobble up some hose and spare AN parts to make an overly long but still function pressure test piece. It stays right st 6 psi. The engine was cold on start up. Would the temperature effect this/ hotter make the pressure increase?

[389]

Its the gasoline. It will change to the warm weather blend in a few weeks and all these goofy things will stop. I've been through this many times on all of my old cars. It would really help to put a 1/4" return line to keep the fuel mixed up.

[crm318]

I was looking under the hood and traced the return line over to the passenger side frame rail. There is the small 1/4" line (with the hose on it from the return on the pump) and the exposed 3/8" line (sticking straight out). I put a tube on the 3/8, poured a little gas down it and then blew into it. It was plugged off somewhere and didn't budge. I did the same to the 1/4" line and it took all of the gas I poured in. When I blew on it, it all came pouring off of the back of the car, obviously not hooked up to the sender. Why wouldn't it leak back there when the car is running. Tomorrow, I'm going to blow compressed air through the 3/8" and see if I can unclog it and see of its hooked up to the sender.

[25stevem]

It’s good that your diving in that deep to get to the bottom of your issue, and as posted the different winter and warmer weather fuel blends can cause your problem since your carbed and not injected.

[rockys1970]

Years ago I owned a 1967 GTO with the original Q-Jet. I had continued flooding problems, even after a full rebuild. After many frustration I finally found the problem.

Under the needle/seat assembly there is a small metal gasket. It seals the bottom of the brass seat to the main bowl casting. If that gasket is missing/leaking, the seat will not seal properly. That means the full fuel pressure will bypass the needle causing flooding. When changing that metal gasket I noticed that the sealing surface on the bowl casting was corroded and pited with metal flaking off. That was causing the flooding problem.

If the 1967 Q-Jet wasn't valuable, I would have just replaced it with a later (68-70) Q-Jet. But I found a solution/repair that worked perfectly. I remachined the casting using a counterbore tool (OD slightly larger than the metal washer) with the proper sized pilot. I used this with a large Pin Vise and by hand, re-cut a new gasket surface until all the pitting was removed. Of coarse, the brass seat is now lower which requires a float adjustment. Worked like a charm.

Not sure if your flooding problem is related to mine but worth a look.

[carbking]

Originally Posted by rockys1970

Years ago I owned a 1967 GTO with the original Q-Jet. I had continued flooding problems, even after a full rebuild. After many frustration I finally found the problem.

Under the needle/seat assembly there is a small metal gasket. It seals the bottom of the brass seat to the main bowl casting. If that gasket is missing/leaking, the seat will not seal properly. That means the full fuel pressure will bypass the needle causing flooding. When changing that metal gasket I noticed that the sealing surface on the bowl casting was corroded and pited with metal flaking off. That was causing the flooding problem.

If the 1967 Q-Jet wasn't valuable, I would have just replaced it with a later (68-70) Q-Jet. But I found a solution/repair that worked perfectly. I remachined the casting using a counterbore tool (OD slightly larger than the metal washer) with the proper sized pilot. I used this with a large Pin Vise and by hand, re-cut a new gasket surface until all the pitting was removed. Of coarse, the brass seat is now lower which requires a float adjustment. Worked like a charm.

Not sure if your flooding problem is related to mine but worth a look.

Rather than bending the float, you could have used a thicker gasket.

Jon.