Thread: SB 350 - Need some advice

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duplicated..

I also remembered later last night that there was a "special" fuel filter for some of those carbs that had a small rubber "flange" to act as a check valve and stop the fuel from running back to the tank. Seems the fuel pump checks didn't always hold well and the carb would empty overnight.

Sounds exactly like your situation. I'll poke around and see if I can't find a picture at least so you can compare with what you've got. Oh, and if you do remove the filter, be very careful when re-installing the filter cover, the threads can be "tender"...

Been searching for a picture of the filter but no joy yet..

Thanks for all the answer !

The diagnose with the empty Float bowls, sound solid. in the beginning i had some problem with the car would drown it self, if i turn it on and start it right away, i had a friend tune the choker and it help on that problem.

34_40: I will look around for the little filter/valve, should it stay on the fuel line, or attached to the carb itself?

Overall i think i eventually will change the carb to a rebuild one, just to see if it help out every problem. I don't think i will do a rebuld myself right now, but maybe as a winter project

Again, thanks alot for all of your help, I really appreciate it

The fuel filter itself has the check valve

Originally Posted by 34_40

The fuel filter itself has the check valve

...and it's behind the fuel line connection at the carb. Like Mike says, be very, very careful with that fitting. There's not many threads in the carb body, and they're soft. There's been a lot of fuel line connections ruined on QJ's over the years by getting them cross threaded and turning them in with a wrench. Start it by hand, and run it in by hand, then snug with a wrench.

Arhh I see, so if the filter not look like this:
Googles billedresultat for http://www.vetteprojects.com/kstyer/images/qjet/thumbs/sm-vette1_038.jpg
Googles billedresultat for http://www.vetteprojects.com/kstyer/images/qjet/thumbs/sm-vette1_087.jpg

I need a replacement ? Is there anything I need to know/be aware before remove the filter ? :-)

Originally Posted by Sherlock_Holmes

Arhh I see, so if the filter not look like this:
Googles billedresultat for http://www.vetteprojects.com/kstyer/images/qjet/thumbs/sm-vette1_038.jpg
Googles billedresultat for http://www.vetteprojects.com/kstyer/images/qjet/thumbs/sm-vette1_087.jpg

I need a replacement ? Is there anything I need to know/be aware before remove the filter ? :-)

The biggest danger is in putting the fitting back into the carb body - steel fitting into the pot metal body, and very easy to cross thread. You may get lucky and fix your drain back problem with a new filter/check valve, but the QJ's were known to leak down through the plugs in the bottom of the float bowl, too. See the link I gave you earlier, and scroll down to the "known troubles - leaking plugs".

I see you found a picture with the check valve in the filter also.. great.

There's a bunch of videos on you tube - search for quadrajet.

Thanks for Your post !

The valve, is it the little shine thing inside the filter, seen from above ? :-)

And if I just want to check out if My own filter look like that, do I have to change any gasket or so While remove it and put it back together ?

The picture you have in the second link shows the check ball inside the filter.

Googles billedresultat for http://www.vetteprojects.com/kstyer/...vette1_087.jpg

if you remove the fuel line, but not the filter housing.. you may (with the help of a mirror) be able to peer inside and see if there is a check valve.

Seems to me It's better to accurately trouble shoot the problem, then replace the defective part.

Try this: run the car a bit, then shut it off. Crack line at the carb, fuel should squirt a bit. If it does, then you know three things: pump works, pump check valve and float valve hold pressure ( at least short term ).

I'm going to assume you do get a squirt. So next, to figure out if the fuel is leaking past the pump check valve. Start the car to pressurize the fuel line, then shut it down. Disconnect the fuel line feeding the pump and plug it. Clamp a small length of fuel hose to the pump, and puttthe other end in a bowl on the floor, let it sit overnight. If you have fuel in the bowl the next morning, then the problem is in the pump.

34_40: thanks for clarification !

Firebird: let me understand correctly. Shut the engine, remove air intake, squeze the fuel line and it will squirt in the carburator ?

2. Disconnect the fuel pump, plug the fuel hose, and let a hose from the fuel pump to a bucket ?

An easier "test" is to go out five minutes early in the morning, after the car's sat idle over night. Take off the air cleaner, boost yourself atop the engine so that you can see down the primary venturi's and pump the throttle with your hand to see if you get a pair of strong squirts of fuel. I'll venture a guess that there will be none.

As for the hose from the pump into a bowl, I'd be concerned that you've changed the hydraulics of the system, opening up the pump suction to atmosphere vs the small amount of suction head on the pump from the tank, and that it will almost certainly drip fuel due to the difference in head from the line, alone, without even considering the fuel in the bowl. With the line in place, if the fuel drains back from the engine, emptying the fuel line, it has to over come the system pressure back to the tank. My guess it leaky plugs in the bottom of the float bowl, but then I may be all wet, too. Given the appearance of that carb it hasn't had any attention for a long, long time....

An area that others haven't mentioned-----The exhaust systm should have a valve on one of the manifolds to close and make the warm exhaust cross over to the other side thru a passage under the carb mounting base that heats the carb and CHOKE bimetal spring in the little tin house on the right side of the carb/manifold. This subsystem not working will cause the problem/symphone as your stating them about car dying when you put it in drive after a cold start---in post #11

Roger's sugestion about the leaking plug under the the bottom of the carb is most likely to be the problem from all complaints. Remove carb J.B. weld the plug and reinstall carb. While have carb off check bimetal to make sure it is connected. One last thing to check if all the above fail is to remove intake and check heat passage in manifold to make sure it is not plugged with carbon