Main.TrailIndexPage | Fuel System | Eliminating Fuel odor in the trunk

Eliminating Fuel Odor from the Trunk

Fuel is dangerous! You can kill yourself. Be very careful and take sufficient precautions when doing anything with the fuel system.

This section is part of Fuel systems. This section is copied from the now defunct Pagoda113 group. It needs editing and clearing up.

Symptoms

I have had a strong petrol odour not only in the boot, but also throughout the interior everytime I filled up the car. I had my 280SL checked out at a Mercedes dealership - they told me I had a leak in my tank and the tank would have to come out and be repaired, so I had since been only filling to the halfway mark to avoid the petrol headaches I was getting.

Solution

Pagoda expert Gernold Nisius of SL-TECH (http://sltechw113.com) says:

On models up to late 1969 with the small vapor tank on the right side of the trunk, the source of gas smell is most often the connection of the metal pipes to the gas tank or the connection to the vapor tank itself.

Remove the filler neck cover and expose the pipe hook up, replace hoses if they are still original. Also check the escape pipe for the vapor tank which runs through the trunk floor and comes out next to the rear muffler and should have a rubber funnel on the end. The funnel was designed to create a vacuum and draw the fumes out,sometimes this pipe is bent, cut, scraped or the funnel is clogged with dirt.

On models late '69 to the end of production the gas tank was plumed into the positive crankcase ventilation system by means of a plastic tank, one way valve and a plastic pipe going forward to the engine. This pipe is connected to the engine just above the ignition pointer on the front of the crankcase with a banjo fitting and draws the vapor stored in the plastic tank into the crank case through engine vacuum. The one-way valve closes the system during low vacuum conditions. The vapor tank is connected to the gas tank with two plastic pipes running along inside the rear body panel and hooks to the gas tank next to the filler neck just like the earlier system. This system has two common problems, number one the vapor tank started leaking fumes because of aging, number two the plastic pipes running through the inside of the rear panel got damaged during body work. On models with this set up it is recommended to replace the vapor tank which comes with new pipes going to the gas tank. The two way valve is rarely the cause of any trouble and is no longer available in the old style. The new style is taken from later models where the valve mounted on the under side of the car.

More general causes which apply to all models:

  • Rusted gas tank along the seam or on top
  • fuel sending unit leaking
  • holes drilled through the trunk floor for accessories and drilled right through the gas tank
  • Also take a closer look at the fuel pump, fuel lines and hoses any leaks here will produce smell and be drawn into the trunk.

Hose replacement

After reading this article, I thought I'd have a look. Sure enough, not only were the old hoses cracked, but one end was completely off at the tank, so petrol was being thrown out of the back of the tank into my boot everytime I planted the foot. So yes, for a few dollars I fixed it quite easily, filled the tank and so far no smell!

Only comment I have is that I bought 1/4" hose and it was a touch too big, I'd go for something slightly smaller in diameter (it looks like normal vacuum hose size to me - but make sure it can withstand fuel).

Another good idea is to check the condition of the three 5" rubber and mesh hoses that connect the vapor circulation pipes to the vapor tank. You'll find them on the inside of your trunk on the right hand rear wall. These hoses....separate from the filler-neck hoses....were original and were sweating gasoline. I replaced them with 3/16 gas-resistant rubber hose and my trunk smells fume-free. Very quick, easy to check and, if you share the problem I had, it costs a dollar to resolve.

My trunk absolutely reeked. I checked around the fuel filler neck and found a puddle of varnish; it's been leaking gas for a while.

I replaced the fossilized hoses coming from the fuel tank as shown below, with 1/4" hose & clamps from the local auto parts shop. That should take care of the leak, but I still need to go through the rest of the vapor evacuation system because it's blocked. My gas cap goes "pssht" every time I open it to fill up -- lots of vapor pressure build-up.

My trunk had a minor gas smell. I saw this article so I pulled off the cover and found that the connecting hoses were damp on the outside from gas. Replacing the hoses and installing clamps cost $3.00. This was a great tip.

Had the same problem, suggest using VW (yes) fuell or vacuum hoses. They are fabric coated on the outside, don't need clamps, (if you don't believe me, try to pull one off, after you pushed it on).
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