I have had ongoing issues with heavy gas smell. Not make you pass out smell but when you go for a drive you smell and the car stinks up the garage when you park after a drive. 350 2bbl Rochester. I've read many past posts. I have checked all the fuel connections and found no leaks and all the lines seem ok with no obvious leaks.

First thought was car was running rich. I adjusted the carb and found both idle screws out at least a full turn too far. Now set to about 2 1/4 turns each. Idled well but border line when in drive. As in almost stalled. I adjusted the main idle (throttle) up a bit and seems much better. Test drive seems fine. BUT this thing still stink like gas.

The engine compartment smells bad which I believe is venting into cabin. But no obvious leaks. Trunk smells fine. Exhaust smells but not smoking once warm. Light smoke when cold.

I'm thinking maybe fuel pump is next try? Maybe bad seal or leaking into gas. Oil didn't seem too bad at last change though. While doing this will replace line to carb and fuel filter in carb.

I had the same problem on my Studebaker many moons ago...last year had same problem on my ALFA, both times it was a leaky fuel pump....I would guess that's your issue too....but wont guarantee it...good luck

Fuel pump, float level too HIGH...

Do you have the proper vented gas cap?

'67-'68 do not have a vented cap. Also, I think there was an 'early' 69 version of non-vented. (not positive, but I think I remember that from somewhere)

You been stiffing too much gas .. lol

67,68 have vented gas caps. It has "VENTED" right on the cap. 69's vent in the truck thru a special line.

https://www.firebirdcentral.com/1967_1968_Firebird_Fuel_Gas_Cap_Correct_p/fue-2058n.htm

Based on the way the gas cap fits on I would say its vented even if it isn't supposed to be! lol Looks original. I'm gonna do the pump and go from there. Best case all fixed. Worse case is I'm replacing at least a 20 year old pump. Pretty cheap either way. Will put an inline filter in while I'm at it. Maybe some nitrous or a blower... or both while I'm at it!!

just bought a new pump last night at auto zone. $20

bill v

That's what happens when you answer questions when you are only half awake! Ugh!
Or like when I argue with my wife. I am usually half right, but it's ALWAYS the 'wrong' half!

After looking to order new pump I have two options: with or without vapor return line. How do I know if I need a vapor return pump or not?

Just look at the pump, if it has one line in and one line out, then you don't have the vapor return...and I don't think the 350 2bbl had it anyway, unless maybe A/C equipped cars.

There will be 2 lines back to the tank for vapor return, a total of 3 lines.

don't use those see thru plastic (or old glass) filters, use a metal....cause if the plastic cracks....you may need a fire extinguisher

X2 400 engines get vapor return

used clear plastic gas filters without issue for years

Where did you put filter in? I'm thinking right before the carb? That would mean cutting the pipe and using "rubber" fuel line to connect each end... leaving the screw in connection to the carb?

The best place in my opinion, is right before the fuel pump, you already have a filter in the carb inlet. This keeps any trash in the gas tank out of the pump. Remember these pumps are just diaphragms, any rust or debris can shorten there life and/or cause leaks.

My 69 350 high output has two lines to the tank. Also the vent in the fill neck with a non vented cap. Often when the pump diaphragm begins to fail fuel can leak from a vent hole in the pump housing.???

To be honest, I like the clear plastic filter near the carb so I can see if gas is in there when debugging problems.

My current car is a collector so I have too maintain stock configuration.

For a driver it would be fine.

Be careful using rubber hoses on your gas lines. Rubber breaks down over time and then you can get leaks. If you cut the fuel line you should flare the ends so that the hose fits tightly to gas-line. Those fuel clamps you get with the filter should be used and NOT gear clamps. People over tighten the gear clamps and thus crack and leak in the future. If the hose will not fit tight with the proper clamp then reconsider your options, If it needs a gear clamp then you are probably not doing it right.

http://www.firebirdcentral.com/1967_1981_Fuel_Gas_Hoses_Set_3_8_Inch_Clamps_I_p/fue-54.htm

I used plastic for years also, but was advised by my mechanic once to replace it with metal.....BTW, I had 'mental issues" with the plastic one once also...when hot, and car running...you could se no gas in it...seemed like it vaporized before going thru...I kept looking at it and saying, "theres no gas going thru, how can the engine be kept running"? lol...

That was one of the requirements at the track. Had to be metal. No plastic or glass filter. Nothing that could crack or break i guess.

Your allowed to install an inline filter with rubber lined
at a race track?

I saw somewhere that you should not install an inline fuel filter before a mechanical pump? Anyone ever heard that or had any problems with that? Seems like the perfect plan to me but... I was hoping to hide one somewhere along the way before the pump.

Also any tips on fuel pump swap. Seems like pretty simple deal to me but will admit have not done one.

Yes its pretty easy, but can be difficult to get the rubber hoses on. I find using new hoses helps as they are softer and more pliable. Also don't over tighten the bolts, the aluminum timing cover is real easy to strip.

Well... nothing is ever easy! Removed old lines and pump without issue other than the pleasant smell of gas. Discovered one of the pump bolts had been replaced with a larger one, must have stripped. Not huge deal except needed to drill larger hole in pump. Snaking pre-bent line through is no picnic either. Finally with some gentle "massaging" it went through. Then I dropped the new fuel filter and it rolled under the carb. 15 minutes later... Napa was kind enough to not give me the 3/8 fuel line I asked for so had to clean up and make a 2nd trip to store. I had removed PCV vacuum lines to more easily deal with the fuel line and of course the old lines cracked. Took divine intervention to get the PCV valve in the new grommet! And to cap it all off I couldn't get the fuel line/pump connection to stop leaking, BUT eventually it did! Went for a ride and noticed a difference. Also noticed a warning light.
Turns out I broke the wire off the water temp senor! Ugh. Too early to tell if my fumes are better as too much spilled gas and such but I'll report back.

That sounds like a typical day in the garage. Just be thankful you don't have to spend the fare and six hours getting off and on ferries to get to the parts store and back.
Real aggravating when you find the part number on the box is not the same as the part number of what's inside.

These pumps are better at pushing fuel than they are at pulling fuel which is why it's not recommended to put a filter between the tank and the pump. But I can see no problem with putting a large capacity filter before the pump. I have a plastic one before the pump on my truck and have recently bought a 100 micron inline for my bird.
Both have mechanical pumps. A large capacity filter has very little pressure drop at rated flow and almost nothing at street/highway use. I like the plastic on the truck as I can see inside to check for debris or water.

Last year one of the five valves in my fuel pump failed, I had starvation while booting it up a large hill in second gear with the rears smoking, rather embarrassing. I took the pump apart and found fine particles lodged in the one valves holding it partially open. A filter before the pump may have prevented that. Could have dirty fuel or,most likely, the 49 year old tank is getting rusty. I haven't had a chance to drop the tank and check.

Sure. As long as it's not glass or plastic. I guess they figure the metal ones won't crack or break as easily.

After new fuel pump, new fuel line from pump to carb, a carb adjustment (was way rich), several new vacuum lines and new PCV, I have run the car several times to see if my gas fumes issue is any better. I think... it smells less. It seems to run smoother, that is to say a bit less growl and a smoother idle Honestly hard to tell much difference.

I had a heck of a time getting the fuel line to seal to carb inlet. It wanted to be very tight which made me nervous but not leaking now. Brass fitting that holds filter also also leaked. Got the brass fitting so that it just weeps ever so slightly and only when running. Doesn't even form a drip but I can see a bit of wetness. I don't dare tighten it anymore and moving it might move the fuel line so I'm just gonna leave it for now.

There is also a couple rubber lines between the sending unit and the metal gas lines. Might want to check them to see if deteriated and allowing gas order through. Also fill up hose from filler cap and tank. Any old rubber may be allowing fumes if deteriated.

Most gas fumes I ever experienced come for the gas cap. I know this was mentioned earlier, but check the seal and get a new cap if you need to. The fumes coming from back there circulate the car and you can smell it all day long. Focus on the cap!

Gas cap is vented. Doesn't that mean it doesn't seal?

supposedly only vents "in"....if it works right

its supposed to let air in to fill void from used up gas...so otherwise tank wont implode..or starve gasoline

I once had an issue with venting not working/plugged on one of my 69s. The vacuum in the tank would become so great that the bottom of the tank would "oil can" and have a "whoosh" of air into the tank when removing the cap. Eventually causing the tank to crack along one of the stamped reinforcement ribs on the bottom of tank. I now know to confirm that the venting is working correctly. Had to replace that tank.😢

I'm happy the gas cap doesn't fall off! If you told me it was supposed to seal I would be worried but venting is not its problem. I was suspect that the tank might have issues. After going for a ride I opened the trunk and smelled around. No issue with fumes in the trunk, and in a couple places you can see the tank. In fact the trunk didn't smell fumy at all.

I am beginning to think I had/have a combination of issues. Worn out fuel pump and hoses. Makes oil gassy and everything smelly. Many small oil leaks, main seal, valve covers etc. Probably some small exhaust leaks too. Not to mention lots of greasy build up on everything. When it all gets hot and flowing it all adds up: running rich, gassy leaking things + oily grease + exhaust = old car smell. I'm going to degrease things as much as possible and give it a good spray this weekend and change the oil now that the fuel pump is replaced. I ordered new valve cover gaskets and replaced the PVC and valve cover grommet . Hopefully that all makes things more pleasant.

Are the oval cover plates in your trunk deck installed?

Yes but there are several small spots where it is rusted through.

I would replace them cover plates and any missing cover panels located behind the back seat next to the speaker tray. Fumes from the tail pipe will travel anywhere there is passage even to the front.

I have few of the factory cover plates if you need them,, otherwise the repo's. Are cheap at classic ind.