Smelling gas
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Freshman User
Joined: Feb 2004
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Smelling gas
I opened the hood today on my 72 F100 w360 and the first thing I smell is gas. The closer I get to the carb the worse it is. I have the 2100 2 barrel carb and was curious why it is dumping gas into the carb when it is not running? It has been running worse lately and I am thinking it may be flooding or something. Any help on this would be appreciated!
Elder User
Joined: Mar 2004
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From: SOUTH CAROLINA
your float may be sticking or have a pin hole in it which makes it fill with gas and sink so you dont stop the gas from entering the bowl. it probably then exits through the vent so you smell gas. or you got a leak. either way a kit wouldn't hurt it.
Posting Legend
Joined: Nov 2001
Posts: 36,506
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From: Grapevine, TX
You might want to check your fuel lines too. I had a couple leaks at the connection to the fuel pump and also in the line between the pump and the carb. You could smell the gas pretty strong under the hood, even though it wasn't leaving a puddle anywhere.
Cargo Master
Joined: Sep 2004
Posts: 2,687
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It wouldn't dump gas into the carb when not running and it's easy as pie to rebuild. The kit comes with a diagram so you'll know how to put everything right back where it goes. Since your truck has been running poorly lately my guess is that the problem is your accelerator pump. Here's how you test it. The accelerator linkage attaches on the front of the carb to a square housing with a screw in each corner. Inside of that housing is the accelerator pump which is nothing more than a spring loaded diaphram. Actuate the accelerator and if you see gas seep out the weep hole the diaphram is bad. You can buy an entire rebuild kit for $12-15 or you can get just the accelerator pump in the HELP! section of a parts store for $4. Swap in the new pump and you're off to the races. If the truck had been running good until the smell of gas then I'd only replace the pump.
Posting Guru
Joined: Mar 2004
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From: Destin/Ft. Walton Beach,
Sorry qman, but yes it can dump gas when not running. It's called residual pressure. The pressure caused by the fuel pump doesn't go away, just because you shut the truck off. Unless your fuel pump is bad, or if you have a leak in the fuel line, the fuel at the feed line to your carb is always under pressure. If you don't believe me, shut your truck off, and then unhook the fuel line form your carb. Better have something there to catch the gas.
Elder User
Joined: Mar 2004
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From: SOUTH CAROLINA
so i guess that the fuel pressure magically disappears as soon as the engine stops running. thats a new one on me.
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Cargo Master
Joined: Sep 2004
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Who said anything about fuel pressure disappearing. I didn't see any such thing. And yes, that would be a new one Einstein.
And you're right steve, there would still be pressure there and if the needle valve wasn't doing it's thing then it would keep coming. But only for a moment until the pressure was released. I thought he was saying that fuel just keeps on coming and coming. And if his float is not operating correctly, or has come unclipped from the fuel inlet or the needle valve tip has wore off then yes it could keep on coming. But I was thinking that if that was the case then he would have it spewing all over the place when the truck is running. When I rebuilt mine I forgot to clip the float onto the fuel inlet and when I started the truck fuel came blowing out of the carb body like a fountain and the truck ran fine.
I've seen in these forums where the accel pump has been the culprit many, many times. Mine was one of them. These are the reasons I said what I did.
And you're right steve, there would still be pressure there and if the needle valve wasn't doing it's thing then it would keep coming. But only for a moment until the pressure was released. I thought he was saying that fuel just keeps on coming and coming. And if his float is not operating correctly, or has come unclipped from the fuel inlet or the needle valve tip has wore off then yes it could keep on coming. But I was thinking that if that was the case then he would have it spewing all over the place when the truck is running. When I rebuilt mine I forgot to clip the float onto the fuel inlet and when I started the truck fuel came blowing out of the carb body like a fountain and the truck ran fine.
I've seen in these forums where the accel pump has been the culprit many, many times. Mine was one of them. These are the reasons I said what I did.
Last edited by qman; Jan 24, 2005 at 06:29 PM.
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Thread Starter
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Freshman User
Joined: Feb 2004
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i think qman may be on to something. it was running great before i started smelling gas. i will try replacing the pump first and see what happens. thanks everyone, i'll let you know how it goes!