560SEL Fuel Smell

[Mikebear79]

I can't take it anymore. My garage smells of a light odor of fuel, it's in my sinuses and my clothes even smell like it. My mechanic tightened the banjo bolt next to the fuel pump which was moist, but it didn't take care of the smell. I have noticed that when I release the gas cap, there's a big hiss that escapes (or gets sucked in, not sure) from pressure. Also, there's a pretty strong fuel smell right around the gas cap area. I just had an emissions test done last week and the cap is one of the things they tested and it passed. Not sure what else to do. I read that there's a pressure release valve that can go bad, but it seems like there's two on the parts websites. Which one do I buy? I guess it's the one that goes in the fender from what I've read. Pic attached. - Mike

[Hit Man X]

Check the EHA o-rings.

[MCallahan]

Yup, if it's got the CIS injection, check the EHA for leaky rings or to see if the EHA itself is going south.

[hapaschold]

I think there s 2 of those fuel system pressure relief valves.

doubt neither still works properly after 27 years

[Mikebear79]

I ordered both EHA rings and both types of purge valves (one for next to the gas tank and one against the left front fender). I'll let you guys know if it makes a difference. - Mike

[Mikebear79]

I ended up replacing the EHA green o-rings, the purge valve under the rear axle and the vacuum-connected purge valve that leads to the charcoal canister in the left front fender. I am still detecting a bit of fuel smell through the vents when I drive around, but that may be due to some residual fuel that sprayed onto the hood pad when I loosened the small bolts on the EHA. I also just last night replaced the oxygen sensor (what a pain!) and have ordered a new OEM gas cap just to make sure. From what I can tell, the exhaust smell seems to be less intense last night and today since new oxygen sensor went in. - Mike

[MCallahan]

Check the EHA again to see if it is drooling fuel out of the little weep holes. If so, you need a new one.

[Duke2.6]

Originally Posted by Mikebear79

I have noticed that when I release the gas cap, there's a big hiss that escapes (or gets sucked in, not sure) from pressure.
Attachment 147130

That means the fuel vapor recovery system should be okay - holds about 1-2 psi pressure or vacuum, but there should be no fuel odor near the cap unless it's been recently removed. Keep checking from the tank exit to the fuel pumps/accumulator cluster under the floor pan and then on to the fuel distributor to the injectors. Let your nose be your guide and look for signs of seepage.

A leak from the PCV system could also produce the odor, so check it thoroughly. Any oil seepage at the oil fill port means the gasket is old, compressed, and needs to be replaced for a good seal.

I'm surprised it would pass a field emission test if the tech detected a fuel odor during the visual inspection.

Duke