HI,

Need some quick advice regarding fuel pumps (external) for my 928 S4. It's become quite noisy especially on warmer days sitting in traffic. I recently refreshed fuel dampers and regulator and filter. At the same time I removed a dead internal fuel pump and simply replaced with the Porsche recommended filter/strainer i.e. no internal fuel pump.

Now the MY87 & 88 S4's did not have an internal fuel pump with the internal fuel pump being intro'd (re-intro'd) from MY89 onwards - at least in Australia. The MY87 & 88 (non-internal fuel pump) are speced with a different fuel pump to that of the S4 models that have an internal fuel pump i.e. MY89 onwards.

The S4 non-internal fuel pump spec (MY87-88) is Porsche P/N 928 608 104 02/Bosch P/N 0 580 464 045 flows 141L per hour. The MY89- is Porsche P/N 928 608 104 03/Bosch P/N 0 580 464 057 and flows 147L per hour. Both are rated at 4 bar pressure. It has been suggested to replace my external pump with Bosch P/N 0 580 464 045 (141L per hour) given that this was the Porsche spec without the internal fuel pump.

What are your thoughts? Why do you think Porsche speced two different fuel pumps with different flow rates?

Thanks in advance

 

Are you sure that the noise you here isn't something running on the pump/filter area's cover? It's common.

 

Both pumps are practically identical apart from a slight difference in fuel flow. I doubt this makes any difference at all under all the different driving conditions our cars see Worldwide. Different ambient temperatures and altitude to name a few.

For those customers that delete the in tank pump and use the strainer I have always recommended the 87/88 pump as it meets the exact same setup. In hindsight now that the 89 plus pump is cheaper it may be better to use that one.

 

i just replaced my external fuel pomp. My car is a euro s4 '88 and had the original 045 pump installed, so that is what i bought again. My car does not have an internal pump.