Fuel filter before or after fuel pump on 1972 280SE?
I have what is probably a silly question, but since I have completely torn my fuel system apart, I thought I would ask...Should the fuel filter be before or after the fuel pump? The manual I have does not have a diagram, and the on-line fuel filters have different fittings than what I took off. What does the fuel filter screen out, since there is another filter in the gas tank? I would have guessed the filter should be before the pump, but on mine there is a larger hose on the fuel pump that was hooked to the tank, and a smaller hose off of the pump that went to the fuel filter. Is that correct?
I'm still can't get fuel through my fuel regulator, even though I have replaced the gas tank filter and the fuel regulator. I've now taken the sysem completely off of the car for testing. The pump starts sucking gas up to a certain pressure and then you can hear it slowing down. I was about to install the inline pressure gauge to see what pressure I was obtaining, before trying to maybe adjust the new Bosch regulator, when I saw this configuration that looked strange to me. What purpose does the fuel filter AFTER the fuel pump serve?
On my car, the fuel filter and fuel pump are located in a single bracket assembly behind the left rear tire.
I broke the system down to it's most simple components. I took the fuel pump with an intake and output hose over a container of gas with a detached car battery. While the pump initially pumped fine, it would start to slow down to a stop. If I drained the pump and let it sit for a while, it would start up fast again and then slow down again. So, there is something wrong with the pump. It did pump out some small particles. I'm assuming the pump can't be repaired, but must be replaced. One more piece in the puzzle.....
Ah, you've changed cars on us. It was a 280SE, now it's a 280SE 4.5 -- whole different ballgame, and yes, the filter is now next to the pump. We get $179 for the pump, and we sell quite a few of them.
Is the fuel filter suppose to be between the tank and the pump, or after the pump? They are mounted with the fuel filter above the pump, but I would have thought the fuel would go through the filter first. However, my existing hoses won't work that way.
Is there a difference in the different brands of fuel pumps available?
And, do you have a recommendation for who sells a replacement fuel tank since mine has a pile of rust particles in the bottom?
The correct fuel pump is Bosch. No one sells new fuel tanks (try a dealer?). Best thing is to have yours vatted. If it isn't up to, you'll probably need to buy one at a salvage yard and have it vatted.
Thank you for the picture! It was connected correctly, with the pump before the filter, but somehow particles still got past the tank screen filter and into the pump.
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