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Just wanted to get second opinions.
I believe it is probably CPS. I just got to work so I haven't been able to connect up my STAR/DAS yet to look for any codes,and won't be able to until I get home this afternoon.
I was on my way to work this AM running about 85 mph, when all of a sudden I lost all power, throttle input had the opposite response as you would expect, it bogged. I basically realized the motor was still spinning because of transmission.
I rolled over onto the shoulder and car fully died all lights lit on dash. tried restarting car and it just spun without trying to catch. waited there about 5 mins while on hold with AAA, and tried it again and it fired right up. so went ahead and drove to work this all sounds like symptoms of CPS. My only exception is I have owned a good number of M112 and M113 powered cars this is my first M113K, and I have never had a CPS failure happen while underway. It has always happened at idle in the past.
Pull the panel in the trunk and look at the relay. Personally, I'm going to say the relay melted due to bad pump(s) and/or clogged fuel filter. DAS will not show any codes for this failure.
An important clue is the engine quitting, turning over but not starting, and then, after cooling for 5 to 15 minutes, the engine will restart. This will only get worse rapidly.
Last edited by bbirdwell; Oct 23, 2017 at 04:45 PM.
Reason: description of failing pump/relay sub-system
I had the exact same symptoms with my w220. It was the cps each time (had a cps failure 3 times over 2 years). If you have an OBDII, it most likely will show a stored error code for CPS (not always though). Now I keep a small kit with the torx bit, wrench, CPS, and a few extra torx screws after I dropped one and took me an hour to find it. I wouldn't lose too much sleep over it, swap it out and i think you'll be back to normal. There are a few youtube videos on how to do it, first time is a little tough since there isn't much room for your hands but after that you'll be a pro.
For a car that won't start....CPS (crank position sensor) vs Fuel pump; Remove the air filters exposing the throttle body, spray a little carb cleaner and try to start the car. If she fires, it's fuel. If she just cranks, maybe CPS. My money is with Barry. Check the fuel pump 30A Maxi fuse in the spare tire compartment, to be followed by FP relay inspection, followed by the filter in the sender, followed by the primary fuel pump. Have you had the fuel pump and sender replaced under the recall? If not let MB pickup the tab. If yes how many miles ago was it done? I just went through this myself.
A car starts and runs intermittently, CPS. I do CPS on all my MB's as preventative maintenance.
So was able to drive home that day after sitting for 10 min. Changed CPS and all was good for until today. It stalled on me twice and the fired again after a few mins. Currently waiting on tow truck. Fuel pumps and tank we're changed a little less than 2 yrs ago due too the recall. Will check relays when I get home.
so just pulled out the relay, it is somewhat melted and the white part of the harness is also melted.
Do I just replace the relay? can I also get the white part of the harness? is there something else I should be checking to see why it obviously overheated. could my pumps/filters already be failing. It has been just shy of 2 years and about 40K miles since everything was replaced. Fuel tank and pumps. Also this relay was by itself next to the air tank. I don't have a spare, so is the fuel pump fuse in the fuse block by the battery?
so just pulled out the relay, it is somewhat melted and the white part of the harness is also melted.
Do I just replace the relay? can I also get the white part of the harness? is there something else I should be checking to see why it obviously overheated. could my pumps/filters already be failing. It has been just shy of 2 years and about 40K miles since everything was replaced. Fuel tank and pumps. Also this relay was by itself next to the air tank. I don't have a spare, so is the fuel pump fuse in the fuse block by the battery?
Do I just replace the relay? Ju$t.....surley you je$t You haven't been under the seat yet to inspect the pump$ and $ender unit.
obviously overheated. could my pumps/filters already be failing.... Ye$$ the primary one for sure,
It has been just shy of 2 years and about 40K miles since everything was replaced. Fuel tank and pumps.......That's about 10k more than whats called for a filter change on most cars. I suspect there will be more victims on MB replacement tank and pumps having failures. Unless they monitor pump current draw ( as per BBirdwells slick little tool) and or change the sender filter on a proper schedule.
Also this relay was by itself next to the air tank.......Only one relay behind the Rt side trunk liner on a 2004.
so is the fuel pump fuse in the fuse block by the battery......Yes,It's on the front of the spare tire well
Resolved. Fuel pump relay and socket remove and replaceRemoved and replaced the fuel pump relay and its socket. Appears that a dirty fuel filter plus partially-clogged pump inlet screens caused an overcurrent condition of the fuel pump motors. Fuel pump relay overheated and literally melted the socket.
I cut out the old socket, crimped and soldered new connectors onto the wires, and installed a new relay.
FWIW: I also learned that only one of the two relays is for the fuel pumps. The other relay is for the electric pump located under the left-front headlight.
For reference, here are the part numbers I located.
Terminals (purchased locally at industrial electric supply house but available through mouser.com):
10-12 gauge 0.250” (6.3mm) female,quick-disconnect, non-insulated with locking tab.
14-16 gauge 0.250” (6.3mm) female,quick-disconnect, non-insulated with locking tab.
Note: the relay coil ground wire is18 gauge and must be doubled over to use the 14-16 ga terminal.
You will need a good wire crimp tool.
Relay positions in the photo are reversed from the OEM factory position. You should ensure which relay powers which circuit before performing any work.
Ok so went to dealer that did my tank and pumps. They looked at records and said the relay wasn't replaced when they did it. I purchased 2 new relays (to have a spare) and inquired on the fuel filter. Ouch $798@ dealer. I am going to order one along with new connector. I installed relay with some dielectric grease, as this is 1 of our 2 dailies ( and only 4 door) took it for a good 20 Mile drive when I stopped I took temp of relay (80 degree ambient) the area at the connector is about 109 F and the top of relay is about 127 F. Could it be the relay had overheated with previous pump... And it just took this long to fail?
Ok so went to dealer that did my tank and pumps. They looked at records and said the relay wasn't replaced when they did it. I purchased 2 new relays (to have a spare) and inquired on the fuel filter. Ouch $798@ dealer. I am going to order one along with new connector. I installed relay with some dielectric grease, as this is 1 of our 2 dailies ( and only 4 door) took it for a good 20 Mile drive when I stopped I took temp of relay (80 degree ambient) the area at the connector is about 109 F and the top of relay is about 127 F. Could it be the relay had overheated with previous pump... And it just took this long to fail?
" Could it be the relay had overheated with previous pump... And it just took this long to fail?" I guess that's possible? Maybe the relay welded itself closed when it got cooked and it finally let go. Interesting that the 30amp maxi fuse did not blow this time around?
Wow!, that's some schloky work preformed by the dealer. What is there work warranty time?
I would at least look at the plug ends on the top of the pump and connector to see if they are cooked. It's not that hard to remove the back seat bottom and the inspection lids to check the connectors. Also would like to know the current draw to the pump. Sounds like you need to find an independent mechanic. That $798 quote is installed correct? the whole sender can be had for around $500 and for those with wrench ability the paper filter can be had for about $40
BTW the sender unit R&R is about 15 to 30 min FWIW
That $798 quote is installed correct? the whole sender can be had for around $500 and for those with wrench ability the paper filter can be had for about $40
BTW the sender unit R&R is about 15 to 30 min FWIW
No that is just for the part, not installed. I do all my own wrenching.
I am going to go ahead and have a look at the pump plugs to see if they are Burnt. The wire side of the relay connector looked fine with no scortching. Also I took relay cover off the only issue I saw with it internally was one of the magnetic coil leads looked burnt.
So just looked at the pump and sender/filter. the connectors still look brand new.
Here's some more info for you. So long as you are replacing the relay and socket, I'd recommend installing a 70-amp relay in lieu of the stock 40-amp relay.
Also, since your car has the fuel pumps ending in part number 00-00, ensure you have the adapter cable. Old pumps had power (striped wires) on pins 1 and 3. New pumps have power (striped wires) on pins 2 and 3. It has been known for dealer mechanics to fail to install the adapter cable; in that case, one pump runs backwards.
FWIW, most plastics will melt around 300 degrees Fahrenheit....
Here's some more info for you. So long as you are replacing the relay and socket, I'd recommend installing a 70-amp relay in lieu of the stock 40-amp relay.
Thanks Barry, I think I will go ahead and order those.
Originally Posted by bbirdwell
Also, since your car has the fuel pumps ending in part number 00-00, ensure you have the adapter cable. Old pumps had power (striped wires) on pins 1 and 3. New pumps have power (striped wires) on pins 2 and 3. It has been known for dealer mechanics to fail to install the adapter cable; in that case, one pump runs backwards.
Yes it has the adapter cable
Originally Posted by bbirdwell
FWIW, most plastics will melt around 300 degrees Fahrenheit....
I currently only replaced the relay because it is a daily, so I will watch the temps for a few days while I wait for the 70 AMP parts. Just drove for an hour in both stop and go 75+ mph highway traffic. When I got to my destination the temp at base of relay was 125F and the top of relay was 151 F
No that is just for the part, not installed. I do all my own wrenching.
So just looked at the pump and sender/filter. the connectors still look brand new.
That dealer is too expesive...
My pins were fine also, but my filter was black. I kept blowing the maxi fuse, cause the primary pump was shot, from trying to pump through the filthy filter. Might want to take some fuel pressure readings.
Yeah I would never buy that from the dealer. I just wanted to see what their price was. I will probably buy from FCP. They aren't the cheapest. But I have utilized their lifetime replacement for all parts, and since these should be replaced often, then I think it's a good idea. My Maxi fuse looks fine, it was a pain to pull.
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