So My girlfriend has a 79 Trans Am with the Olds 403 in it. Yesterday it just died on her in the parking lot. It would not start back up. I pulled the spark plug and seen spark. Moved the throttle and the accellorator did not pump any fuel. Checked the gas gauge and we're good there Removed the fuel line to the carb and I'm getting fuel. Removed the month old fuel filter and tried to start it. Still no gas in the carb and wont start. So I poured some gas down the carb and it idled for a few seconds. I'm assuming something is blocked inside the stock 4bbl carb. Prior to this the car ran normal. I think it's the rochester quadrajet. I'll check out WAC for a manual for instructions. I plan on taking it apart this weekend. Any ideas on what's causing it to not start?

 

Dirt in the inlet? Float stuck?? Choke hung? As you stated probably in carb.

 

I was thinking the float might be stuck. When I removed the fuel line it seemed to let off pressure. Is opening the top of the carb the only way to check/fix that? Choke seemed fine. Might be dirt or something clogging it somewhere. Filter was clean.

 

Best way to check it would be to take the top off the carb. Has it ever been rebuilt? It's probably due. I'd guess either your needle and seat is stuck or the acc pump cup blew apart.

 

Get a kit, just in case, and pull the top off the carb, carefully.
Look at the needle valve, and I'll bet the little spring clip that holds it to the float, either came off, or broke!
Bad thing is it doesn't come with most kits, and you'll need another carb to get it from, if it broke!

 

Not sure the history of the carb. Probably has not been rebuilt. Car only has 66K miles on it. I'll get a kit and check it out. Thanks guys. I'll see if I can rebuild it.

 

I always just buy a Holley....quadrajets are fine carbs when they are fed fuel regularly...but become troublesome after years of use.
Holley's usually run perfect..right from the box.
Just a thought.

 

New paper filters have check valves which I have heard sometimes fail. This could be the problem, a bad spring loaded check valve on the fuel filter.... just a thought.

 

It is hard to beat a properly set up Quadrajet for the street. But if you are going to tear into one, make sure you know what you are doing. Doug Roe wrote an excellent book years ago, and Cliff Ruggles wrote and even better one a couple years ago. With ethanol and other additives in todays gas, some of the parts store kits are junk. Get a good kit from www.cliffshighperformance.com and do it right. He also will have any and all other carb parts you need. His kits contain a lot more than parts store kits and the rubber parts are impervious to any crap in the gas. My 3 cars with Q-jets start, idle and run perfectly all day, every day.

 

Cliff is back logged for years...guys waiting for him to rebuild stuff..says something about the quad.
The kits are excellent...but the carbs are problematic...if you have no experience.
Another vote for the book.

 

It is almost impossible to tell if a fuel filter is plugged just by looking at it! Did you try leaving the filter out? The bronze sintered filters can be plugged solid but still look new. And as mentioned earlier, the paper filters can have a bad check valve. Before you rip the lid of that Q-Jet, replace or bypass the filter and see if that cures the problem!

 

Check out Sparky. He did mine and stands by his work.
http://www.sparkyscarbs.com/

 

Yeah I mentioned that I removed the fuel filter. It's the paper type and it's only about a month old. Still no fuel with the filter out but I can always try that again. Much easier than taking the top off.

 

How about a little trouble shooting 101 before tearing the carb apart or (God forbid) buying a Holley? Since the car started when you poured gas in the carb (that was step one), it is CLEARLY a fuel delivery problem. Step two is to disconnect the fuel line from the carb, direct it into a cup (you may want to clamp a length of rubber hose over the end of the metal line to make this easier) and crank the engine for a few seconds to see if you get fuel in the cup. If you do, it's time for a carb rebuild. If not, you either have a bad pump, a cracked rubber suction line between the tank and the pump, or crud in the tank that's blocking the inlet screen. Explore each of those to find the problem.

 

And in a testament to the advertising software on this website, as soon as I submitted my post above mentioning Holley carbs, an ad appears for carbs at Summit...

 

I turned it over with the fuel line off and it pumped gas. I still have not tore apart yet but plan on trying some last minute stuff this week before taking the carb top off. I want to keep it stock since it's a low mileage stock car that's pretty nice. So a Holley is out of the question.

 

Q-Jets aren't that hard - just intimidating!
With the kit there should be a sheet showing pictures of all the parts, and where they go.
Like I said - the clip for the needle 'hanger' to the float bowl would be the first place I'd look, and if that's O.K., the float itself may have filled with fuel, and they can be ordered.
Just look real hard for hidden screws while disassembly, and they must go back in the same holes.
Apon reassembly, I try to snug all the screws the same, and tighten in a criss-cross pattern.

 

So I pull the fuel filter out and crank on it til it starts to slow down then the darn thing starts. I guess when I tried it before I did not crank enough. I was in a parking lot and could not get my car next to it to jump it if needed.

 

That is good news! I have rebuilt my share of carbs and the Q-Jets are always tough, but they are good mixers!

Keep an eye on it though. Many years ago my ex-wife was having car troubles where her car would die at random but when I would get there it would start and run fine. Turns out the fuel pump was intermittent!