mAMG

Ive changed the fuel sending unit today. The car worked fine and everything was normal.

Once I tried to start it after couple of hours, i heard something blown in back seat. Car dyied. Now it cranks but never starts.

- CPS changed a month ago.
- Fuel pump changed one year ago.
- Fuel pump comes on when key on positon 2.
- Before changing the sending unit it was working fine.
- After changing the sending unit it worked fine till I reached home.
- Tried to pull codes but nothing is stored ...

Is it possible that the mechanic did not re-install the fuel pump correctly when he changed the sending unit ?

.....

Denroll

Did you check the fuses/relays in the trunk?

You can do a visual inspection of the pumps and sender to see if everything looks OK. Access is really easy. The rear seat can be removed in 10 seconds. There is one metal tab on the bottom of each side that needs to be pressed, then the whole cushion lifts right out. You will see the pumps on one side and the sender on the other. If the collars aren't over-tightened, you can use a flat tip screwdriver and a hammer to take them off.

mAMG

Checked them. Everything looks normal. I can feel the pump working when I turn the key to position 2.

novae500

Any chance that the wiring harness didn't "click/snap" snug when reattaching them?

Denroll

Maybe it's just a loose connector. If you pull the seat cushion, you can see the connectors without having to remove the collars.

mAMG

Checked. Everything looks normal.

I remember the click on the pump wire is broken so it doesn't click anymore. But it has been working for a year normally. Even after the sending unit changed it worked fine and was pulling hard.

Even now when i put my hands on the pump when i turn the key to position 2 can feel something vibrating/turning on ...

211.070

Open the tank back up, and make sure that one of the lines did not come off of the pumps. Just open the pump side.

menace2sobriety

^^ THIS - This is exactly what happened to mine, where the sender lines clip into the pump(s) you should push them down until you hear them snap into place, initially I pushed mine on tight (no snap) and car ran and idled for a couple of minutes and then I heard a pop, and the car died and wouldn't start again, opened up the pump side to find the lines had popped off

Takes 5-10 minutes to remove everything to check, that's where I would start

sexyxe

100% agree with the above posts. I drove my car for a day or two before mine popped off. As you say, car will crank but not start. You will hear and feel the pumps working, but they aren't sending any fuel. Gotta pull the rear seat out, take off the cover, then it should be obvious if the line has popped off. Car will then start up straight away.

mAMG

Thank you everyone.

The problem is fixed. It was as mentioned above the line popped off. Now it works fine

jhk777

similar problem. 2007 C280. Very low fuel pressure at rail. Changed fuel pump (passenger side in my car). Car started right up, ran great for 10 minutes. I shut off, then tried restart-----crank but no start. I don't have the loaner fuel pressure tester any longer but fuel is a trickle at the Schrader valve on the fuel rail, even with the key in #2 position.
I can barely hear the fuel pump activate with key at #2 ( but currently in the middle of noisy thundershowers). looked again at fuel pump---fuel line connection is intact, and 4 prong electrical connector plugged in fully.

Any thoughts here?? Disconnect at the (driver side) sender unit? Fuse is good, and relay clicks when energized. Switched it with an identical relay in engine compartment fuse box and no difference.

Bad new fuel pump?

Appreciate any ideas.

hayseed

iTrader: (2)

maybe starving fuel from dirty/clogged filter or the pickup is dirty,,,, unlikely bad new pump but it happens

jhk777

I replace both the fuel pump (passenger side) and the fuel sender (driver's side) and still have an intermittent no start. Car runs great when it does start.
Now at an Indy shop---they want to replace the crankshaft position sensor with an OEM part (mine was from Autozone as I replaced this on a Sunday).
Indy shop says the ECU needs to reprogrammed--obviously I don't have the software or hardware for this.
Hope this fixes it.

C32owner

Flip hope you come right, very interested to hear your fix. I am going through similar problem right now.. And have replaced like everything but still no joy... This is 1 month in to the issue now... Loosing my mind

jhk777

My indy shop just called ----the OEM crankshaft position sensor didn't change anything. Technician was able to reproduce the intermittent no start. He traced it down to no voltage to the fuel pump when the ECU is warm. Says it needs a new ECU--reportedly a TSB on this ECU malfunction when ECU gets warm, but I haven't found it yet.
Car runs great when it does start----not sure why the fuel pump would still function when driving for hours and ECU obviously warm/hot.

ECU $1500 plus $150 labor. ouch!!

C32owner

Cool thanks for the update. My secondary pump just won't switch on when required think at about 3000rpm or something.. It initially runs when ignition turns on to prime the system then turns off after a few seconds. It won't switch on again when needed and also gets no voltage.. Apparently my indy says had the ecu checked but showed no problems..think I must ask again. Glad you came right eventually.. Hope it definitely is the ecu

jhk777

Apparently, the technician said there was a voltage drop in the signal to the fuel pump fuse or relay as the engine and ECU got warmer---at least that is how he explained it. I read that some on this site have their ECU "flashed" or "reflashed." I think mine has a fault that needs replacing.
If anyone comes across the TSB for this problem I would be interested.

C32: hope you can sort out the issue.

jhk777

found the TSB thru my local library online resource.

DTB
Date:
March 17, 2009
Order No.:
S-B-54.21/215a
Supersedes:
S-B-54.21/215 dated Feb. 11, 2009
Group:
54
Revision History
Revision
Date
Purpose
a
3/17/09
Technical Content Revised
-
2/11/09
Initial issue
SUBJECT:
All Models Equipped with Engine M272 and M273
Engine Cannot Be Started When Engine is Hot but Will Start After Engine has Cooled
If you receive customer reports in the above model vehicles that the engine cannot be started when the engine is hot but will start after the engine has cooled and there are no Diagnostic Trouble Codes stored in the ME control unit, check the signal that activates the fuel pump from the ME Control unit by monitoring pin 17 + and pin 4 on the small socket of N3/10 ME Control unit:
1. With the key in position 2 there should be 12 volts present across the pins, if not check the wiring from the ME control unit to the fuel pump relay or the fuel pump control module.
2. When cranking the engine, the 12 volts should go to 0 volts, if not it may be due to an open circuit in the ME control unit. In this case, replace the ME control unit and retest the signal to the fuel pump relay or the fuel pump control module. Refer to EPCnet for applicable part number. Note: A copy of the short test and all tests performed must accompany returned parts. If the documentation is missing or does not support the diagnosis, the warranty claim may be debited. Note: The following allowable labor operations should be used when submitting a warranty claim for this repair. This information has been generated on March 17, 2009. Please refer to Netstar �� Star TekInfo �� Star Time for the most current labor time allowance

Rudeney

I've never seen anything like that paste on a CPS. Maybe there is a tiny leak seeping from the rear seal and it's combining with metal filings form the starter gear? Or, maybe someone replaced the starter and though it would be a good idea to grease its gear?

layzie12g

Why didn't you just take the car to the dealer and get a whole new pump and tank for free under the recall???

Strigoi

This thread was posted 2 years ago and OP isn't in the US. I don't believe the tank replacement applies to people in other countries.