Fuel smell when brake are applied.

[geno]

On my 85 Riv. with a 307 engine, I get a fuel smell after the car has been driven for a few miles and after I set at say a traffic light for a minute or so with the brakes applied. I have check an replace vaccum lines, replaced TPS purge that goes to the canister The caniseter appears to be OK also. The oder goes away after I start to drive agan. There also not any codes set.

Any one have any ideas?

[Dave@Moon]

You may have a simple fuel leak and the action of moving down the street is enough to dissipate the odor. I'd carefully inspect the fuel lines and injector connections for residue/leaks. If you have a fuel pressure guage, attach it to the schraeder valve and see if the pressure in the fuel rail drops rapidly at shutoff. That would be a dead give-away.

I just had to replace the fuel rail on my dad's Dodge 3.3L ($220!!!) when it began to leak through a seam. In that case the leak was barely noticable on a Tuesday (weak odor in turns and at stops), and by Friday there were large puddles of gas on and under the engine!

Good luck!

[geno]

Dave@Moon

That was the first thing I check out. the 85's were still carburated and ran at low fuel pressue. I might also add if I shift into neutral of park and take my foot off the brakes, the smell is not as pronounced. This lead me to think it might be vaccum related. Carb has new float and at the correct hieght also.

Thanks for the reply,

[rocketraider]

Check condition of the rubber fuel lines at the tank end. If either the fuel return or canister vent line are bad, you'll get fuel odor at standstill that will dissipate when moving.

Also- here's a long shot but I've seen it happen. The power brake vacuum source hose has a filter in it between engine and brake booster (round black plastic device mounted vertically in the line). It was originally installed in the mid-70s cars to eliminate a problem they were having with gasoline fumes getting from the intake manifold into the brake booster, where they condensed back into liquid gasoline and rotted the brake booster diaphrams with resulting loss of power brakes. That filter may have gone bad.

[Guest]

Gene,

This sounds dumb but its true. I had a terrible fuel odor on my wife's car (it was not a Buick so its not worth mentioning), anyway all I had her do was fill up at a different gas station and the odor went away. My best guess is she got a bad batch of gas. I never had the problem return.

[Guest brh]

Forgot to log in!!!

[geno]

Thanks for the replies.

This has been hapening for a little while now so I don't think it is the gas and we fuel all 5 of our family cars at the same place. I think I'll give rocketradier's idea a try.