theoneuafter

I recently had my ml diagnosed at mercedes and they determined the fuel pump was bad because of the level sensor reading wrong and creating a no start condition. They wanted $2000 to install the pump and I about fell off my chair!

I put in a new fuel pump and now the pump will not prime. if i put 12 volts directly to the pump it works and if i spray starting fluid in the intake it starts right up.

I checked the fuse and installed a new relay and still no go. At the plug that goes into the fuel pump, i tested it for voltage and I get 10.37 volts with the key on.

I was also told to put a new crankshaft position sensor in and try it, but i put a new one in about a month ago. Could a bad crank or cam sensor cause the pump not to prime????

I would really appreciate the help, I've been at this for a few days now and I really need to get this up and running!

eeferber

$2000

had a problem like this on my old '99 ML430. Ended up the pump was fine, it was a sensor of some sort. $200 fix

junior22g

I put in a new crank sensor tonight and nothing.
Still won't prime.
Any other suggestions?

davey one

If you have power up to the pump and you know it runs, try another earth from the pump, the other thing is there is a timer that runs the pump for only 10 seconds(with ign on) if you do not start the engine ,in case of fire in a head on crash.

avks

same issue, any luck?

theoneuafter

Yes it is fixed. My family and I were leaving for Disney days after my last post. I had no choice but to let the dealership fix it. They did however cover half the cost. My part was $1037.00

It turns out there are two pumps, one on each side. When I found this out I got a little pissed because my service advisor told me there was one. I just didnt have the time before we left to do the proper research on this. I definitely could have fixed this myself.

The level sensor on the driver side was bad, The advisor said there was only one pump behind the passenger side seat.
Now I want to punch him in the face. lol. jokes.

I went to pick up the truck when we got back, and I went in there very firm. I noticed a copy of the service record for my truck, The one that says all the work that was done since day one.

I told him the least he could do was let me have that copy for all my trouble. He haphazardly agreed and I took it. the receptionist was pissed that I took it. she was throwing her phone on her desk and shuffling things all around in an angry manner. didnt phase me on bit.

Now I know how to fix this issue and may be able to help someone else.

I told them also I wanted all the old parts. They had the nerve to charge me a parts disposal fee. lol I had them remove it.
any questions you guys may have, post them up. I will help as best I can!

avks

Ahh, I was getting the same run around. Mercedes of Manhattan was telling me there are two and the one in Queens was telling me there is only one.

I wound up replacing the pass side pump but when I check with a volt meter it looks like I'm not getting 12volts to the cable when the key is switched on. The relay is working and fuses are fine so it's driving me nuts!!

Did yours stop starting all of a sudden? I never had an issue while driving but one night I suddenly had a problem where I turned the car off and it wouldn't start. It was random at first but now it's been a week and it hasn't started.

Only works with the starter fluid.

Any idea how to access the driver's side pump? Under the seat I think there is an amplifier so not sure if we gotta pull all that out to get to that.

theoneuafter

I will also add that after our ml was rear ended, the replaced the front differential out of warranty totally free, so I guess all is not lost.

theoneuafter

yes I had the exact same issues you are describing. I tested the power to the passenger side pump and got 10.25v
the driver side pump comes out the same way as the passenger side. you must remove the cover and swap that one out too.

it is a saddle tank with reservoirs on both sides. the pumps work in unison to keep equal amounts of fuel on both sides of the tank.

theoneuafter

mine also.started randomly and then not at all. fuses relay and everything all good.
Started right up with starting fluid as well!

avks

Hmm, I guess the only difference I'm having is I'm not getting the power to the pump. Also, did you test the power by taking the plug out from the top of the pump and using an altimeter? I think white/red was positive and the orange was the ground.

I'm a little surprised that the pump wouldn't turn on because of a faulty level sensor...you should've still heard the pump come on when turning ignition to on- no???

theoneuafter

I thought I wasnt getting power. but I got around 10.25 or 10.37v at the pump. I unplugged the plug at the top of tbe pump and tested that with the key on. I cant remember which colors were witch. I still have the pump in a box. I can take a look.

I think the pumps work together in some way. after I put the new pump in, I wouldnt prime.

avks

Hm, yeah, I tested the same cable with the key on and have been getting 0 but am getting 12v at the fuse and I can hear the relay click (and have changed it). The only thing that's driving me nuts is why I'm not getting any power out of that cable.

Can you post the part number for the driver's side one when you get a chance? I can't find it online anywhere.

theoneuafter

the part # of the pump I got myself turned out ti be the same one the dealer used. I had them replace both. the part # is A 164 470 19 94

I looked at the pump too on the new pump the red wire is positive and the ground is brown.
they ar right next to each other on the pump. if you are looking at the plug on the pump straight on the red wire is the right most wire. The brown one is on the left right next to it.
you can match it up that way to test yours again.

if you want pm me your cell# and I will text you a pic of the new pump I have. it is the same one the dealer put back in there.

Vimototv

Hi i own a merc w203 1.8 kompressor, so ralay and fuse is ok, if i remove the pump on passenger side and i test it conecting a battery neg and pos, fuel pump works very good, but if i put it back to the tank and connect it then no prime, i seta volt meter on the red and black wires unattached from pump and it reads 10.40 as soon ai i connect them back to the pump terminals it reads 0 nada!!.

for your experience you say that a sensor on the drivers side is the problem? what is the sensor you are talking about? the level lever with the float?

my cel is +527225651966 whatss app too i will preciated your sugestions to fix my problem

Maj. Dundee

You are on the wrong forum.

https://mbworld.org/forums/c-class-w203-3/

C230 Sport Coup

So what was the resolution to this issue?
Our ML refused to start this morning,
just checked the fuel pressure.
Nada. Now determining where the fuse and relay are.

What next? Replace both pumps at once?
Will that fix it?

EDIT: After doing some reading, I'm not seeing that theres 2 pumps.
One side has the pump, the other the 'sending unit' with the filter.
Since mine has never been replaced, thinking of doing both? Yes?
Is there really another pump somewhere?

Flex9

Hi, I noticed your attention to detail in your posting and hoped you or someone would be able to lend a hand with a similar problem that was noted in the forum. My car has a no start condition (it cranks). There is no fuel pressure at the Fuel Rail Test Port. There is no power at the Rear Cargo Fuse Box, fuse 57 (20A). Fuse is good. Removed the Fuel pump relay KO) and I strangely find B+ at pin 5 (87) with key off. I also find B+ at pin 1(86) with key on. Pin 2 has 3.85 volt with Key on. Not sure why this is? When the vehicle shut down and failed to start, the codes registered were: 0341 CMP position sensor A; 0337 CKP Low input & 0120. Is it possible that these strange readings and lack of fuel pressure could be related to the timing sensor codes (CMP & CKP) causing the Fuel not to operate? I cleared these codes and cranked the vehicle 5 diff times. I rescanned, but did not get a return of these codes. Any help would sincerely be appreciated.

Juicyvic

I already tried replacing sensors and nothing. But its a 2015.