Fuel Overflow Leak - PeachParts Mercedes-Benz Forum

tobybul · #1 06-29-2006, 07:13 PM

85 300D
I just noticed that fuel is draining/leaking from the drain which I believe comes from the fuel fill drain towards the rear. My tank is 3/4 full right now. I just filled yesterday. It appears it has been draining/leaking as I smell fuel when I stop.

Could it be that the fuel is foaming and thus overflowing?? I can't imagine having a tank leak as its well protected behind the rear seat.

Any thoughts????

TheDon · #2 06-29-2006, 07:21 PM

is it visibly coming from the rear tank? sure no leaking return supply lines on the injectors? or on the underside of the tank the short rubber pieces become brittle with age and will leak

tobybul · #3 06-29-2006, 08:17 PM

Quote:

Originally Posted by TheDon

is it visibly coming from the rear tank? sure no leaking return supply lines on the injectors? or on the underside of the tank the short rubber pieces become brittle with age and will leak

Its obvious that it is draining from the rubber hose coming from the fill cap area. I opened the back panel in the trunk and traced it. I noticed the draining stopped a few minutes after I opened the fuel fill cap. It was kinda damp in the fill area initially.

tangofox007 · #4 06-29-2006, 08:49 PM

Is it possible that your fuel cap was on properly secured? Like one of the tabs not engaged?

I made a left turn one time on a full tank. The police car behind me turned on the blue lights. I was certain that the light was still green. The officer said that I had not done anything wrong, but he observed gasoline spilling from my fuel tank when I turned. (I assured him that he did not see any gasoline spilling from a 300D!!!) But I did find that the fuel cap was only partially engaged, and fuel was in fact leaking out of the filler neck.

tobybul · #5 06-29-2006, 09:01 PM

Quote:

Originally Posted by tangofox007

Is it possible that your fuel cap was on properly secured? Like one of the tabs not engaged?

I made a left turn one time on a full tank. The police car behind me turned on the blue lights. I was certain that the light was still green. The officer said that I had not done anything wrong, but he observed gasoline spilling from my fuel tank when I turned. (I assured him that he did not see any gasoline spilling from a 300D!!!) But I did find that the fuel cap was only partially engaged, and fuel was in fact leaking out of the filler neck.

Its possible. Although that was the first thing I checked. But I'll see how it goes tomorrow.

I also just changed the fuel filter (nothing to do with the other issue). I started the car and it seems to be chugging a bit. May be cuz I didnt tighten the primer handle? Does some air in the line affect the fuel delivery? can't seem to help not getting air in there after priming....

tangofox007 · #6 06-29-2006, 09:32 PM

Quote:

Originally Posted by tobybul

I also just changed the fuel filter (nothing to do with the other issue). I started the car and it seems to be chugging a bit. May be cuz I didnt tighten the primer handle? Does some air in the line affect the fuel delivery? can't seem to help not getting air in there after priming....

I highly recommend the new Bosch primer pump.

tobybul · #7 06-29-2006, 10:03 PM

Quote:

Originally Posted by tangofox007

I highly recommend the new Bosch primer pump.

what is a primer pump? is this an external pump tool or a replacement to the car's primer?

KylePavao · #8 06-29-2006, 10:08 PM

This new Bosch primer pump replaces the one currently installed on your car, which tend to leak and let in air. The plastic handle that unscrews, and then gets pushed down to prime is your primer pump. Luckily the 115's (my car) have a simple one that just presses down.

KPMB82 · #9 06-29-2006, 10:19 PM

could be your vent line is clogged. as the day gets hot the tank is pressurized. and will vent out the filler cap if the vent is clogged. vent line runs under the car and comes out by the frame rail on the left side under the rear passenger floor. you should be able to blow air in the vent line.if you haven't already I suggest you replace the flexable fuel lines.

tobybul · #10 06-29-2006, 10:22 PM

Quote:

Originally Posted by KylePavao

This new Bosch primer pump replaces the one currently installed on your car, which tend to leak and let in air. The plastic handle that unscrews, and then gets pushed down to prime is your primer pump. Luckily the 115's (my car) have a simple one that just presses down.

so whats the diff betw the bosch and whats in da car?

KPMB82 · #11 06-29-2006, 10:33 PM

new type does not have a screw out cap/pump. has a button on the end.

tobybul · #12 06-29-2006, 10:42 PM

Quote:

Originally Posted by KPMB82

could be your vent line is clogged. as the day gets hot the tank is pressurized. and will vent out the filler cap if the vent is clogged. vent line runs under the car and comes out by the frame rail on the left side under the rear passenger floor. you should be able to blow air in the vent line.if you haven't already I suggest you replace the flexable fuel lines.

thanks. this may be it. if the vent is clogged, what would clogg it? and what would blowing it do. i realize it should clear ir but if the clogg is something solid.......

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