E21 Fuel tank cleaning

[petroscf]

Hey, is there anyone having any idea about if and how can one clean the fuel tank?
My car is having various problems (starting cold, but also even when driving and the temp is at normal levels the car may turn off!!) which I have noticed that exist when the fuel in the tank is at 1/2 or lower, and disappear when the tank is full.
So I was thinking that these problems might be due to various little objects such as mud or other, that have been getting into the tank with the fuel (not all gas stations are selling very clean fuel...)all these years (my car is dating from 1977, so 32 years, almost 33)...One may reply that this is the job that the fuel filter does, but isn't there any chance that some object may be so small that are able to pass the filter?)
I think that if I cleaned the tank completely from everything and re-fill it once, all the problems of this type should end...
Any ideas???

[3050rpm]

My 2-cents worth is that if you've had this car for nearly 33 years, you're obviously taking care of it, including changing the fuel filter on a regular basis. True, gas at the station can be contaminated, but aside from moisture contamination the filter should take care of that. Rather than go through all the trouble of cleaning the fuel tanks, consider that what you're experiencing might be due to fuel pumps that need replacing. The E21 has two pumps, a main one and a kind of "pre-pump" located in the fuel tank itself. My guess, and it's just a guess, is that the pre-pump is worn, and needs to be replaced. I don't know what the diagnostics are for checking it out, but I suggest doing that first before more dramatic measures.

[petroscf]

Thanx, really!! I'll try to check this out!