300SE fuel pump replacement

When inspecting the SLS in my 300SE, I noticed that the fuel pump was seeping fuel.    It wasn’t enough to smell fuel, so I am not sure how long it had been like that.   I’ve owned the 300SE for about four and half years and have not done the fuel pump replacement job.

300SE fuel pump replacement

As I keep a spare Bosch fuel pump and filter, I figured I should change it ASAP.   In my view, it makes little sense to change out the pump and not do the filter at the same time.   I changed the filter when I did the accumulator about four years ago, and it was very dirty.   I think my car sat for some time, so the tank is probably a bit dirty.

My 300SE is an 86 model, so it has the single pump setup.   Obviously the first thing I did was disconnect the battery before working on the pump.   This job is not difficult but hard to do without spilling fuel everywhere.   I own some fuel line clamps, but of course I forgot to use them and sprayed myself with fuel.   This was rather uncomfortable as it soaked into my socks.    Its important not use vice grips here, as they will chafe the fuel lines.   I was able to push the handle of my ratchet into the fuel line to keep the stream of fuel at bay.

fuel pump replacementI am glad that I decided to change the filter.  After four years and about 12,000km, it was filthy.  I think this is also the reason why my fuel gauge flickers at lower levels.   I suspect after sitting for a while there is debris in the fuel tank.   This filter was not as bad as last time though.   Its also not been bad enough to affect the running of the car.   In my old 1988 560SEC, I ran out of Petrol.  The didn’t run properly until I changed the filter.   Given the debris in the bottom of the 300SE tank, I shouldn’t ever let it get too low.

fuel pump replacementFuel pump replacement is one of my least favourite jobs.   I’m glad its sorted out, but I really don’t enjoy doing this one.   I’ll probably be doing the filter again in a couple of years to see if there is still debris in there.

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