Raw fuel smell

[Bowtied13]

Hey guys I'm new on the forum, I was just a lurker for quite a while. So hopefully I'm doing this right. Here's a picture of my truck. It's a 1984 C10 Silverado, sb350 with a 700R4.

Over the last while when I drive my truck it smells like raw fuel really strong in the cab. I could never pinpoint where it was coming from. Well today I jumped in the truck to go somewhere. Before I started it I depressed the brake pedal, as I did it made a hissing noise (like air leaking) and suddenly I was hit with a pretty strong smell of fuel. I took my foot off and did it again. Same thing happened. It's been happening for a long time but I just now was able to connect it with the brake pedal.

I don't know if it's some sort of vacuum leak with the brake booster or something. Has anybody experienced anything like that?

[Dead Parrot]

A booster leak should not cause a gas smell. Booster leaks suck air in, not let gas out. Still worth checking the booster out. Bad brakes can lead to large fuel spills when you smash into the thing in front of you.

A little gas can create a lot of smell. Had a similar issue a while back. Turned out to be a small leak on the mechanical fuel pump. Never enough to drip on to the ground, just enough to make the pump damp when cool.

Other suspects: bad gas tank vent system, slow carb leak(every Q-jet I have owned has leaked out of the fuel filter casting plug after a few years.)

[tucsonjwt]

I would check to see if the gaskets on your Qjet look wet, indicating a carburetor leak. Also, I would also crawl under the truck and check all of the rubber fuel lines and check to see if the vapor recovery canister smells like gas. The recovery tanks load up with fuel after a while and need to be replaced.

[Bowtied13]

Thanks for the input. I'll take a look at it this evening. If it helps I'm running a Holley 650 Cfm street Avenger

[Bowtied13]

Upon further inspection it appears that the vapor recovery canister had been removed from the truck in the past. I did an engine swap on it about 6 years ago (from the original 305 to my built 350) and may have unknowingly taken it off.

From what I have researched the vapor canister should look like the top picture.

What is this ball looking thing that's bolted to the firewall in the second picture?

[tucsonjwt]

That is a vacuum canister (reservoir) which stores up vacuum to assist HVAC and cruise control, etc.

I don't know if the evap system has any vacuum associated with it - I have never had an evap equipped truck.

http://www.classicindustries.com/pro...ts/ap7330.html