faulty fuel pressure regulator?
 

The fuel pump in my '95 E320 wagon started making noise recently. In general, no noticable drivability problems with on exception. On right turns, the engine will stumble as if starved for fuel for a couple seconds then clear up and be fine.

I started by changing the fuel filter...same thing. Next I changed the fuel pump...again, same thing. Can a faulty fuel pressure regulator cause the fuel pump to work hard enough to vibrate and make a loud buzzing noise? If not, what else should I be looking at?

Car is a W124, 3.2 M104. 177,000 miles.

Thanks!

Fuel pressure on that should be 55-60psi...IF the pressure is too high then you should have a check engine lamp & drive-ability problems...also the fuel mileage should be WAY down...

Have the fuel pressure & delivery volume checked..very easy..about 5-10 minutes

Sounds like fuel contamination to me.

No CEL but there is a stored code 4 in the diagnostics module.

Also pin 14, gives codes 5 and 11.

I'll try to check fuel pressure this weekend...