I smell gas from my 6 banger

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cudajim

cudajim

cudajim
Joined
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Grass Valley, Ca.
I have a 225 slant six on my 67 Barracuda and smell gas under the hood (much more than normal). I smelled it both before and after I rebuilt the 1 bbl holley carb and I don't see any obvious signs of gas anywhere. Any ideas where to look? I'm also getting really crappy mileage but it runs fairly well. It's got a Chrysler orange box for ignition. Any ideas?
 
Just a thought,, on a trip across the country with my 67 Dart I was smelling gas while driving. When I would stop, open the hood, nothing.no smell everything dry. I would check it when hot, cold still nothing.What was happening was as rpms were up while driving the fuel pump was leaking. By the time I'd stop the engine heat and shutdown the gas would evaporate.Drove me nuts for 2400 miles.Should have known because the fuel milage was off. Just last week it happened to my truck(318) but I caught this one.After start up I got stuff out of the bed and when walking back to the truck I noticed a few drips so I opened the hood and sure enough the pump was wet.My shop is 3 miles away so when I got there,poped the hood and it was dry as a old bone.One was on the shelf so on it went.Again just a thought
 
I thought about the pump too but it's new, as is all rubber gas lines. I will check it again this weekend while it's running.
 
As soon as you shut your engine off quickly open your choke and see if you see gas dripping into your intake from your Carb it could be draining your gas bowl . just a thought, my one barrel I was running did this..
 
Well it don't run on fritos.
 
memike said:
As soon as you shut your engine off quickly open your choke and see if you see gas dripping into your intake from your Carb it could be draining your gas bowl . just a thought, my one barrel I was running did this..
Click to expand...

Ok, so what was the fix? I'm suspecting a high float level.
 
cudajim said:
Ok, so what was the fix? I'm suspecting a high float level.
Click to expand...
Could be the accelerator pump plunger you see on top of the carb could be rotted , If the float was set wrong it would flood all the time. in the carb is a plunger and a check ball inside the carb, we have way better tec's here to help you on this then me..
I hope one jumps in and helps you out..
 
Of course you smell gas! What do you think this car runs on, COAL?!!!
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memike said:
Could be the accelerator pump plunger you see on top of the carb could be rotted , If the float was set wrong it would flood all the time. in the carb is a plunger and a check ball inside the carb, we have way better tec's here to help you on this then me..
I hope one jumps in and helps you out..
Click to expand...

There is no plunger on top and no check ball that I am aware of. The plunger is on the side and it's a diaphram not a plunger.
 
Memike had a Carter BBS carb in mind, not your Holley 1920, when he wrote about the plunger.

Make sure the manifold heat control valve is free and working correctly, not stuck or hacked by someone who didn't understand why it's there and why it should be kept in working condition.

Do the Fuel line mod. Put in a new float (the float on the 1920 is made of nitrophyll foam and will absorb gas and grow heavy, so even if it's set at the correct height you'll have a borderline flood condition). Use a quality carb kit with a good inlet needle/seat such as the one from www.daytonaparts.com -- good luck setting the float with the completely inadequate dumb little strip-of-paper-ruler "float gauge" all the kits come with these days. :roll: Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download.

Make sure you're using the correct 3/8" thick carb base (to intake) gasket, not the 1/8" thin one. If you've been running with the thin one, and you install the thick one, you'll need to readjust your kickdown linkage (if the car has an automatic transmission), making it longer to account for the carb having been lifted.

If that doesn't do the job, make a heat shield for the carb like the factory '80s item, see here.

Be advised that you will smell gasoline from any pre-'71 car (pre-'70 in California) because of the open carb bowl and fuel tank vents that just dump directly to atmosphere. The post '71/'70 cars have closed vent systems that dramatically reduce the amount of fuel vapor released to the air, and one of the benefits of that is much, much less fuel stink.
 
By the way, If your fuel contains 10 percent ethanol your fuel hoses should be replaced with barrier lined fuel hose.

The talk of 15 percent ethanol coming will play havoc on our fuel pumps causing the 'rubber' parts to fail.

Time to think about electric fuel pumps and related electrical circuits with a oil pressure switch wired to the relay to shut down the pump when the engine dies but the key is on.

Or think about a Holly TBI fuel injection system with O2 sensor for closed loop operation and better milage and performance. No laptop required.
 
Closed-loop operation is terrific, and a good TBI system is definitely better than a carb, but Holley's TBI system is overpriced junk. Active thread on the subject of TBI retrofit is here. Replacing all the fuel hose with fuel injection hose (labelled "30R9") is an excellent idea; make sure to use fuel injection hose clamps (with rolled edges). I don't agree that an electric fuel pump is necessary or desirable on a carbureted vehicle; they tend to cause more problems than they solve (see here).
 
Thanks for the replies - I am already running with a thick gasket and my float has been replaced. The heat control valve is loose and working properly. I also recently rebuilt the carb. The gas smell was there before I rebuilt it and is still prevalent. I've owned old Valiants in the past and they never smelled this bad. I also replaced all rubber gas lines recently. I guess I'll have to dig deeper into this.
 
Darter6 said:
Just a thought,, on a trip across the country with my 67 Dart I was smelling gas while driving. When I would stop, open the hood, nothing.no smell everything dry. I would check it when hot, cold still nothing.What was happening was as rpms were up while driving the fuel pump was leaking. By the time I'd stop the engine heat and shutdown the gas would evaporate.Drove me nuts for 2400 miles.Should have known because the fuel milage was off. Just last week it happened to my truck(318) but I caught this one.After start up I got stuff out of the bed and when walking back to the truck I noticed a few drips so I opened the hood and sure enough the pump was wet.My shop is 3 miles away so when I got there,poped the hood and it was dry as a old bone.One was on the shelf so on it went.Again just a thought
Click to expand...

Had the same thing happen last year. Although I filled the crankcase with gas. I thought it was the carb so I rebuilt it. Changed the oil (mostly gas) and drove it a few days only to fill the damn crankcase again!

Then a good fellow here suggested the pump was leaking into the engine. Never crossed my mind that it could do that.

My 225 should be nice and clean for a rebuild... cause it sure smokes alot now :banghead:
 
I don't think gas in the crankcase is a problem but I will check it carefully. The last time I checked the oil it was clean and not discolored or too full etc. The mechanical fuel pump is also new.
 
the accelerator pump will leak not into the carb, but out a weep hole in a crease of the carb casting: left side, between the bowl casting and the venturi casting. Gets a little dangerous if its spewing gas onto the hot intake/exhaust logs!
 
Update - I was able to drop the tank this past weekend and replaced the donut at the filler tube. The old one was split and was seeping just enough to cause a problem but not enough to cause a major drip. Anyhow, the smell went away so it's fixed.
 
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