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Also check the main filter and sock filters on the pumps as they get blocked
That relay and socket look very familiar...
Agree on the filters; I replaced my pumps and filters at 92,000 miles (I will not make that mistake again!) and the sock filters were showing significant contaminants. Tank was clean but then again, the pumps and filters were 10 years old.
When I replaced the relay two years ago I took some temperature measurements using an IR thermometer. In each of the following cases, I took temperature measurements on two consecutive days.
May 2015: 40-amp relay case temperature approximately 55 degrees F above ambient trunk temperature. i.e. 117 degrees in trunk, relay case measured 171 degrees.
May 2017 (two years and 32,000 miles): 40-amp relay case temperature approximately 70 degrees F above ambient trunk temperature.
June 2017: 70-amp relay case temperature approximately 42 degrees F above ambient trunk temperature.
I'll see about taking a few more readings but eventually I'm going to want to replace the side cover in the trunk....
After a week of checking relay temperatures daily, I will say I recommend upgrading the stock 40-amp relay to the 70-amp relay with 9.5mm power lead connectors.
Relay temperature is consistently 40-42 degrees F above ambient; significantly lower than the temperatures measured with the smaller relay.
If your relay goes bad, go ahead and obtain an 80-amp socket with the 6.3mm and 9.5mm copper connectors, and a 70-amp relay. Be sure to crimp the connectors securely and solder. The carbon assembly paste will not hurt while you're in there. Or...just replace the stock relay with the upgraded relay as preventive maintenance; it only takes an hour or so.
It's time for me to put the panels back into the trunk.
Out of curiosity, I inspected my fuse and relay today (11/04 built MY05)
At 88k miles, the pump is original (42nd week '04), but the filter must have been changed as it's dated 21st week of '07.
At idle and a very low level in the tank it's pulling 20.2A
No signs of any overheating of the fuse/relay, however the connector at the pump has been hot.
I intend changing the in tank filter and rechecking.
Out of curiosity, I inspected my fuse and relay today (11/04 built MY05)
At 88k miles, the pump is original (42nd week '04), but the filter must have been changed as it's dated 21st week of '07.
At idle and a very low level in the tank it's pulling 20.2A
No signs of any overheating of the fuse/relay, however the connector at the pump has been hot.
I intend changing the in tank filter and rechecking.
That amperage doesn't look right but it would only be conjecture on my part to hypothesize why it is so low compared to the current pump...the latest pumps pull 12-13 amps each (24-26 total) when wired correctly. If one pump is pulling 12 amps and the other 3 amps, someone forgot to install the adapter cable and the lower amperage pump is running backwards.
I recommend you change your fuel pumps and filter now. If possible, upgrade to the latest parts to include the adapter cables (one for each side). Multiple posts on this. If you can find "new" old stock with the obsolete part numbers, you may be able to save a few bucks with them.
If original, the pump part number would be a 211-470-17-94. It has since been replaced but the new pump requires an adapter cable since the power and grounds are reversed compared to the old pump. Newest pump is a 211-470-00-00.
Ditto for the newer fuel filters; the third version 211-470-64-94 requires the adapter cable. The two previous versions do not.
You cannot mix and match obsolete and latter versions of the fuel pumps and filters; the fuel line connectors are different on the pumps' internal connections. So...if you are going to replace the filter, you might as well get the latest and replace the fuel pumps at the same time. The connector in the photo looks pretty ugly...do it once and do it right.
Thanks for your input.
I'm surprized you considered 20.2A to be low.
I thought I had read where you wrote in another thread that WIS states to change the filter if the pump current exceeds 20A at idle, so wouldn't >20 be considered high?
As an experiment, I fitted a R2432P filter in the LHS filter assembly.
This filter is 3-4mm shorter overall that the original, but the length of the spigots inside the assembly are more than long enough to make up for this. It fits very nicely, but does have reduced surface area when compared to the original.
Pump current remained at 20.2A afterwards.
I guess there are a couple possible reasons for this.
1. the pump sees the new filter as being an equal restriction to the old one because; a) the reduced surface area; or b) the old one wasn't that badly blocked and both filters flow as much as the pump can push.
2. the restriction in my case may be the sock on the suction side of the pump.
Thanks for your input regarding the part numbers.
Does anyone know if the rebranded Airtex E8572M pump is interchangeable for the old or new MB part number pump?
Thanks for your input.
I'm surprized you considered 20.2A to be low.
I thought I had read where you wrote in another thread that WIS states to change the filter if the pump current exceeds 20A at idle, so wouldn't >20 be considered high?
Thanks for your input regarding the part numbers.
Does anyone know if the rebranded Airtex E8572M pump is interchangeable for the old or new MB part number pump?
I remember posting that; that info I obtained off the Internet and it did state to change the filter if the pump current exceeds the 20 amps. I went back and relooked it and document's attached photo shows what I now know to be the PWM control modules for an E63. So, it looks like what I wrote then should apply to the E63 and not the E55.
I would posit that the PWM controllers on the E63 are "smart" compared to our relay-controlled E55 so the E63 controllers ramp down the amperage at idle. Since the E63 has a fuel pressure sensor and the E55 doesn't I'm somewhat comfortable with my conjecture; I'll need to see if I can find some more info on them.
I built a dual ammeter that plugs inline with my E55 fuel pumps. I've never had them run at less than 13 amps each (except for the time one pump was wired backwards and only drew 3 amps).
I did see your gadget to measure pump current. (I've read every single E55 fuel pump/filter thread the internet has to offer :-)
I'll tear into the other side and see if I can measure individual pump currents.
My primary concern is starving the motor at WOT and hurting a piston. I have a spare WBo2 setup, so I'll probably install that when time permits.
Just posting the schematic plus color and wire size info for the relay replacement. EDIT 30 July 2020. Revised schematic is here: https://mbworld.org/forums/w211-amg/...ml#post8120332
Erroneous schematic previously located here is now deleted. Apologies for any confusion. My bad.
Last edited by bbirdwell; Jul 30, 2020 at 11:07 AM.
So does the Airtex pump have the same fittings as the old MB pump, or the new MB pump?
From photos it appears that the fittings for the Airtex are compatible with the old MB filter/regulator (aka "Delivery Unit" #55) P/N 211-470-24-94 which was superseded by P/N 211-470-51-94.
Both of the above were superseded by P/N 211-470-64-94 which has different fuel fittings and is not compatible with the Airtex.
Last edited by bbirdwell; Oct 15, 2017 at 08:38 PM.
From photos it appears that the fittings for the Airtex are compatible with the old MB filter/regulator (aka "Delivery Unit" #55) P/N 211-470-24-94 which was superseded by P/N 211-470-51-94.
Both of the above were superseded by P/N 211-470-64-94 which has different fuel fittings and is not compatible with the Airtex.
I'm revisiting this issue as my 4 year old 36,000 mile "new" fuel pumps that were replaced with the complete tank are starting to show signs of overheating- the typical browned areas around the connectors on the fuel tank plate and darkened female pins on the car side of the harness. I've already upgraded to a single heavy duty 75 amp relay and replaced the wiring from the rear power distribution block with 8 gauge wire. The small female connector pins simply cannot handle the constant amp draw and I'm struggling to find a permanent solution. I think the male pins are ok, it's the female pins not allowing 100% surface contact that creates the heat. Soldering wires directly to the fuel hat pins would probably not be a good idea...if they were to overheat the solder could melt- let alone the fact there's many gallons of gasoline underneath.
Did you check the amp draw and or fuel pressure?
You could have gotten the bottom of a dirty tank from a gas station and your filter is plugging. May want to do a visual on paper element. Also might want to try that Carbon Conductive Assembly Paste Barry posted early in the thread.
Okay, I thought about the pros/cons of going to a three-relay system. I've decided to instead go with a higher-capacity relay.
Thoughts:
- Prior to 1 June 2005, E55s used one connection from the rear SAM to activate one relay. The relay coil resistance indicates the relay needs about 0.3 amps from the rear SAM to trigger.
- On and after 1 June 2005, the E55 used two connections from the rear SAM to activate two relays (one connection per relay). This implies the drivers in the rear SAM can only support the 0.3 amps (plus safety margin) each relay requires. Having two connections implies connecting two relays to one activation line would draw too much current (~ 0.6 to 0.7 amps to trigger two relays from one line) and could potentially burn out the driver chip in the rear SAM.
- The fuel pump relay in the pre-1June 2005 E55 is rated at 40 amps resistive, 35 amps inductive. The fuel pumps draw approximately 27 amps through this single relay. Call it 67% of rated load carried constantly. (FWIW, I measured the temperature of my relay at 148 degrees F on the outside of the case today.)
- The fuel pump relays in the post-1 June 2005 E55 are also rated at 40 amps but only have to pass through approximately 13 amps each. Call it 33% of rated load carried constantly.
- I located a 70-amp resistive rated relay that uses 9.5mm connectors versus the stock 40-amp relay 6.3mm connectors. So...I need to remove the connectors from the stock relay socket, insert the 6.3mm trigger/ground connectors into the new socket, cut the 6.3mm power leads from the fuel pump circuits, crimp and solder the 9.5mm connectors onto the power leads, insert 9.5mm connectors into the new socket, then insert the new 70-amp rated relay. Now I should be looking at 39% of rated load carried constantly.
- Proposed relay has a slightly higher coil resistance that indicates approximately 0.25 amps current required from the rear SAM to trigger the relay. So...rear SAM should be safe.
Parts ordered today. I'll see about making time in the next 2-3 weeks to adapt the larger relay (I don't have to deal with the bean counters trying to save $2 to $5 per car) and post results. If this doesn't work, I'll fall back on the three-relay design.
I'm still bothered by having a 30-amp fuse on a circuit that draws 24-27 amps. The E63 stepped the circuit up to a 40-amp fuse. I'll have to look at the wire gauge to see if it can support a 40-amp fuse without melting insulation. That would be a "bad thing".
EDIT: for the fuel pump relay, the rear SAM does not source current, it "sinks" it; i.e. it connects the circuit to ground. See the schematic for the relay later in this thread.
Do you recommend upgrading the relay's if the vehicle is an 06 model year then or does it seem like they've solved the issue by having two relays?
Do you recommend upgrading the relay's if the vehicle is an 06 model year then or does it seem like they've solved the issue by having two relays?
Negative on the upgrade for an '06 model. I would personally trust the 2006 model's two relays to prevent the earlier model meltdown. When I sell my '05 I'll be looking for an '06 or later E55 or E63.
Negative on the upgrade for an '06 model. I would personally trust the 2006 model's two relays to prevent the earlier model meltdown. When I sell my '05 I'll be looking for an '06 or later E55 or E63.
Cool, thank you for the information and research you've done.
Admittedly, I looked into this due to some posts I've seen on e55's combusting into flames due to fuel issues. That has made me feel really uneasy about owning this vehicle and carrying my kids around in it. This specific issue is just related to the fuel relay's going bad and no longer letting the fuel pump function right?
Do you have any knowledge about the fuel system malfunctions causing fires in these vehicles?
Just some FYI of what I did that could help some one.The over heat is due to the return less system that runs high pressure all the time. Although I converted to a return less system and a Kenne Bell boost a pump, I run a separate 75 amp relay that is triggered by the fuel pump supply power wires so the load is now on the 75 amp relay that is wired to the battery only, not the factory power supply. Still works as it should safety wise with the key and will shut off in an accident as well since factory wiring is still active.
Has anyone purchased the relay socket pack mentioned earlier and have a spare they're willing to sell? I just started having issues with my relay needing to be re seated and I'm assuming it's due to how burnt up the socket is. Looks like the specific socket is not available on Amazon or anywhere else that I can find other than from China and I don't want to wait a month to get it. I did some searching but couldn't come up with anything other than lower amperage sockets. Thanks
Or I guess better question this socket should work with the flosser 2270, right? Terminals are 6.3 and 9.5
Has anyone purchased the relay socket pack mentioned earlier and have a spare they're willing to sell? I just started having issues with my relay needing to be re seated and I'm assuming it's due to how burnt up the socket is. Looks like the specific socket is not available on Amazon or anywhere else that I can find other than from China and I don't want to wait a month to get it. I did some searching but couldn't come up with anything other than lower amperage sockets. Thanks
I have several spare sockets and connector packs. PM me your mailing/shipping address and I'll drop a socket with the connectors in the mail tomorrow. These are the same that I posted earlier in the thread.
I PMd you Barry but also posting this here in case anyone else has come across it or will in the future:
I got everything wired up with the new relay but the car isn’t getting power to the pumps. When I jump the fuel pump circuit pins 30/87 or manually apply 12v to pin 86 the pumps run fine, so I think I can eliminate the relay and actual fuse pump circuit as being the problem. But for good measure I replaced the 30amp fuse (this is on the fuel pump circuit and not the trigger circuit right? Or no?) and tested the spare relay I got with no change. When I hook a multimeter up to the trigger circuit pins 86/85 it reads 0 and jumps to .06mv when the pumps should be running, basically nothing. Fuse 43 is not blown and I replaced it anyway for good measure. Anyone have any ideas on what I could try next?
Last edited by corvettekyle; Jul 30, 2020 at 08:03 AM.
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