Truck Smells Like Gas

[FordFarmer]

After shutting down the truck smells like gas. Cant really smell it from the cab but from outside you can. Been that way since I bought it a couple months ago. No apparent fuel leaks. Stock 302 with a 2100 on top. Going to start by checking fuel pressure at carb. Any other ideas?

 

[70_Steve]

Stock 302 with a 2100 on top. Going to start by checking fuel pressure at carb. Any other ideas?

What year? Pre-sometime_in_71 the gas tanks used a vented cap. The vent was only one way, allowing air into the tank but nothing back out of the tank. This allows pressure to build in the tank depending on the situation. A cool evening and a warm day will allow the vapor to expand. Almost every time I refuel, when I pull the cap there's pressure in the tamk. So, if the cap doesn't seal tight, you will smell the gas vapor.

Also, from what I remember the 2100 fuel bowl vent was open to atmosphere.

 

[patterdale]

I'm going to vote for dirt on top of the rear tank causing rust/leak. I had it on our 76 years ago.

 

[76Broncofromhell]

What year? Pre-sometime_in_71 the gas tanks used a vented cap. The vent was only one way, allowing air into the tank but nothing back out of the tank. This allows pressure to build in the tank depending on the situation. A cool evening and a warm day will allow the vapor to expand. Almost every time I refuel, when I pull the cap there's pressure in the tamk. So, if the cap doesn't seal tight, you will smell the gas vapor.

Also, from what I remember the 2100 fuel bowl vent was open to atmosphere.

This is where the terminology gets confusing. "Vented" in older cars (Pre 1970) meant that it would quite literally let fuel vapor escape to the atmosphere. It was vented both ways. Later model caps have a check valve in them to prevent most tank emissions. This is what the smog stations test - to make sure the cap is not venting to the atmosphere but still allowing air past to keep the tank from collapsing. Chances are you have bad seals on your gas caps.

 

[notagain]

Check the hoses to the gas tanks. Sometimes they look OK but if they're in really rough shape sometimes they weep and it's tough to see.

 

[broncnaz]

X2 check your hoses, filler cap gaskets ect. As was said all gas caps were vented just early ones had the 2 way vent all later ones had the one way vent.

 

[jckkys]

In a place with no moving air the fuel vapor will flow like a liquid because it's heavier than air. By getting underneath you can use your nose to track down the source.