-88 560 fuel pump unstable

Hi,

today I heard my fuel pump running uneven. It runs fine for 2-4 seconds, then it stops for 1/10 seconds and then continues. The interval varies of course. I have not heard this before.
My wife filled the tank completely with 95 unleaded, but I cant see that should be a problem for the pump?

Is my pump approaching its retirement?

Hi Erik,

I guess Erik is your first name, wou!d be good if you sign your posts.

I believe that there is no issue with your fuel pumps (you have two pumps) but with your fuel pump relay, which is located behind the glove box.

The relays are known to have issues with the soldering points. If there is a contact issue the pump stops working like you described but may stop working at all.

This may also cause the issue you described in your second post. If the pumps have just short outages the fuel pressure may not be sufficient to allow proper funcion of the fuel injection.

Regards,
Ralf

Hi Ralf,

ok, thanks for the tip. This could explain both issues. I will wait and see how it develops.

Rgds Erik

Hi Erik,

I would not really wait. If the fuel pump relay is the issue it will stop working completely sonner or later which would require you to call road assistance. It could also overheat if it has contact issues and cause serious damage on the relay socket.

Regards,
Ralf

Hi Erik,
as Ralf described, change the Fuelpump Relais for save. Tis is the QuickTime and cheapescway to test if your Problems an missfirings gets solved. If not, you have to Look further on.

Hi Erik,

take an easy approach. Have a 4 mm short cable with 2 4mm banana plugs and a fuse in between. Pull out fuel pump relay and read pin 15 and 87. Connect both. Now fuel pumpt should run when ignition is on. If you can drive now without any hickups, you know that FPR is your problem.