Has anyone replaced their fuel pump on the C32 with a better pump? I heard a long time ago there some of the early fuel pumps were could not supply the engine with enough fuel at high RPM ranges for a sustained period of time. Would an E55 fuel pump fit?

As an aside... how do you search for phrases? I tried searching for "fuel pump" but of course all the results were about the I/C pump.

 

I believe the C32's fuel pump is integrated into the fuel tank. To replace the pump, you replace the entire tank. Therefore, I can't see any way to upgrade the fuel pump.

 

ScottW911 is, of course, correct. On the US version of the C32, the fuel pumps are only available as a complete assembly which (ostensibly for evaporative emissions concerns) includes the tank as well. The ROW market variants have pumps which are available separately. I’d have thought that the Stuttgart anti-Autobahn factions would have addressed any potential unburned HC sources with the same zeal as our regulatory authorities. Alas, such is not the case. When mine fails, I’ll catch up with MBenzNL for some Euro upgrades so that a second mortgage won’t be necessary.

Based on A/F readings, my relatively stock configuration supplies more than sufficient fuel to the engine to allow the DME to adjust its directives accordingly. It has never run lean. During extended WOT sessions, it’ll dump extra fuel through to help cool the pistons and reduce its proclivity for pre-ignition. It runs too rich at times, even with the OE pump. If it’s functioning properly, the stock pump is more that sufficient for ~300 WHP.

The good news is that because you are piloting a SLK32, your pump setup is entirely different from what’s essentially the same drivetrain as is in our taxis. Your pump is external and therefore readily accessible. Since the R170 forum in not exactly a hotbed of activity, please know you are always welcome to post here. If you do indeed need additional flow and/or pressure, the Walbro pumps are highly regarded among high-performance aftermarket tuners. Due to copyright restrictions, I’m unable to include the appropriate schematics from M-B’s EPC, but take comfort in knowing any necessary pump replacements will be as easy as swapping the fuel filter. PM me if you care to receive even more worthless information.

 

I was told that the fuel pumps are separate ie outside the fuel tank on W203 starting 2003.

 

Thanks for the info. What if the car has considerable more than 300 whp? I already have Renntech pulley, ECU, cams, and larger SL55 intake. I've having custom headers/exhaust built now as well has getting a larger heat exchanger. I'll get dynos but I expect have at least 350 whp.

With some of the mods on to some of the C32s on this forum, I would expect some to running at least that much power so I thought this might have been visited already.

 

i would suggest running an inline external pump if you are only looking to make a small deal more power

do not confuse this with a "booster pump" cuz those things are garbage...

 

If you just want to increase flow, use a FMU, not a boost a pump. Boost a pump just regulates power going to the pump, it doesn't actually increase flow.

 

I believe there was another fuel pump that AMG installed on the cars when the limiter was raised from 155 to 176.

If I could get my hands on this offering at a reasonable price I would be very interested in it. I would prefer to take this route than a band aide approach.