This 2006 Sprinter lost all power over 50 mph but would restart fine. Replaced fuel filter, no help. By the time it got home, it wouldn't go over 20 mph. We had been noticing a loud and worsening "growl" from the fuel pump over the past weeks. (Fuel pump had been "replaced" fourteen month ago at a shop. $900.00 +)

Following the manual suggestions found that the pump pressure (static, no flow) was over 50 psi (manual said pump "OK") while the pressure with flow to the injector pump/regulator dropped to 30 psi (no mention in manual).

Following suggestions from these pages and the mercedes pages, ordered up a fuel pressure regulator from Europarts of SD (great service) . Using the very small hands of a girlfriend, managed to get it in without having to remove the injector pump (it is on the bottom of the low pressure side). HOWEVER, problem did not resolve!!!!!!

The manual did make one passing mention of the flow rate, about 3qt/min (actually xxx gal/hour) so I tried that and found only 1pt/min actual flow. Dropped the tank, removed the pump module but, being a wkend was unable to source a replacement. I tried to find the problem but the module was "NON-REPAIRABLE! I managed to get it apart without damage.

The real problem was/is that the DESIGN ENGINEERS placed a screen on the bottom of the fuel pump, inside the "non-repairable" fuel pump module, a $400.00 PLUS part that requires dropping the fuel tank to replace. This module sits in a sump at the bottom of the tank and has a "gravel strainer" molded into its base to exclude anything over 1/16th inch. Inside the module, located about 1/4 " above the bottom (snapped over the end of the pump) is a flat screen (about 2 1/2" dia) of fine mesh, not much larger than tooth brush bristles.

This screen was completely loaded with gunk. The pump was passing only 1 pint of fuel a minute and the growling noise was the pump CAVITATING!!!!!!

I cleaned the screen (used a fine tip screwdriver gently scraping with hot water and dish soap, then a stiff toothbrush) and reassembled the module.

The pump is now quiet and pumping 3 quarts of fuel a minute. The SPRINTER is back on the road.

To open the module: Near the bottom end of the rod having the long spring is a "crimp" or "teat", placed there to prevent dissassembly. I ground it off using a small hand grinder (dremmel tool) and, noting how things went togather, took the module appart. Turns out that the crimp is not really needed once the fuel lines stiffen with age.

While this fix may not be cost effective at the dealer, given today's shop rates, it certainly is very cost and time effective for the home or inhouse mechanic since the dissassembly and fix took only an hour after the tank was on the ground. No special tools were required either.

DON'T forget to clean out the bottom of the tank!