Fuel Flow Problems

[ctaylor738]

Recently, I saw a post about fuel flow problems in a 280SE.

MB 280SE Coupe idles ok, no pull

I was having a similar problem in my 280SE, and I fixed it. I think my experience will be instructive for the 108-114-115-116 crowd, or anyone having flow problems with a fuel system that has the inverted cone tank strainer.

Just above the threads in the strainer, there is an approx 2.5 mm groove with four slots in it. The fuel flows through the strainer and through the slots. If you go to one of the online places and pull up a picture of the fuel strainer, you will see what I mean.

There is a similar groove in the tank just above the threads. The outlet tube is fed through that groove. So the fuel flows through the strainer and slots in the base, into the groove (half in the tank, half in the strainer assembly) and out the tube.

What had happened to my car was that what looked like a combination of old fuel and rust had accumulated in the groove in the tank, effectively blocking the flow. This was nasty stuff. I had to dig, and I mean dig, it out with a bent piece of coat hanger. I took me at least a half hour and a good part of a can of brake spray to get it all out. Fuel flow is excellent now.

You might be able to blow some of it out, but that would probably only affect the area near the exit tube. It would be difficult to clean it out with the tank in the car because the fuel drips forever when you remove the strainer.

[cth350]

i have a completely clogged up gas tank sitting on the side of the house I pulled from a 6.3. I took the easy way out and got a spare take off ebay for 35$ plus shipping.

I guess it's about time to pull the drain plug on the original. When I siphoned the 11 year old gas out of the tank using a length of 1/2" hose and a drill-mounted pump, the rust clogged up the hose. There's a ton of crap in that tank.

There's a shop near me that I'm friendly with that will boil the tank out. Given the amount of crud from the tank, I don't know if the walls are so badly pitted that this would be a waste of time and effort. If he has to spend a few hours bead blasting the inside of the tank to clean it up, it won't be worth the effort. (I'd rather spend that cash recoring the very tired radiator).

BTW, to pull that drain plug, you need a 24mm allen key. When I first did this ages ago, I went to the MB dealership and they sold me a tool for 20$. It was a really big bolt with two nuts jammed together and held with a small tack weld. I laughed when I saw the tool and complemented some unseen engineer for the simplicity of the solution. I then realized I could make my own for one quarter the price, so I was out lots of cash. Oh well.

-CTH

[Arthur Dalton]

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The plug is 22mm and a Tech trick is to use an inverted 1/2 drive spark plug socket.. you put a 1/2 drive extension into the plug socket from the socket opening end and use the hex head of the socket as the allen hex..then just use a regular 1/2 drive ratchet/breaker bar on the extension..You all have these in your tool box.