d1no

Ah screw it, its hard to get those damn black lock rings without hitting it with a hammer and screw driver, I dont feel like taking it out unless I necessarily have to replace the fuel pump. Can anyone else chime on on the fuel pressure test I did and what that noise in the video is?

cpbeasley

didnt john just go through this same thing? read through his efforts. theres a tool you ca purchase to make a quick job of the lock ring

d1no

Not quite the same thing but yes he did replace his fuel pump. His failed to start the car at all so he had no choice. My car still starts and its been like 2 months with this problem. It just has a hard start, so it may not be the fuel pump. but I am sure its something fuel related. The tool cost 140 from the dealer, its stupid because that thing cost like 5-10 bucks to produce but w.e. I can do it with hammer and screwdriver

d1no

OK so when I put the key in ignition to pressure system the psi on gauge go to about 20-30 and i can hear the fuel pump prime but then the psi on the gauge drop immediately. Then I start the car and the psi go up and down on the gauge till it starts and it stays at 32ish psi. Turn car off and psi goes back to 0 immediately. The way I understand it is that it shouldnt drop the pressure this fast at all? What problem would this point to?

cpbeasley

why dont you PM John or Glyn since you arent getting an audience

d1no

^ I was hoping they would see the thread but I guess ill pm them.

Xhale707

When did you replace ur fuel filter?

d1no

At the same time I did the spark plugs, so like 3k miles ago or 4-5 months. I did it toward end of summer maybe september. Problem started 2 months after that when it got cold out.

Glyn M Ruck

d1no - sorry for not being on the board - have friends out from Canada. You have insufficient fuel pressure. The injection system on a 230K is different to the V6 but you must have adequate pressure & the injectors must have full pressure at start up or the vehicle will not start.

Xhale's comments are correct. First suspects are the fuel pump, strainer, & filter with pressure regulator.

Your video is indistinct but that high pitched whine sounds like the fuel pump screaming it's lungs off & cavitating. Listen to it with the back seat out - you should be able to easily hear the pump. It will cavitate/have trouble reaching pressure, if it is worn or the strainer is blocked.

Good luck & let us know - your problem is fuel.

johnand

+1. Also want to comment, that my late W203 is different than yours. Mine has the pump on the passenger side with integrated sending unit. On the drivers side is the other sending unit and integrated fuel filter. The way I understand it, your fuel pump is on the driver's side with integrated sender, and the passenger side is the other sender. Your pressure regulator is built into the fuel filter that is located on the driver's side of the tank.

I would suggest you replace the fuel filter again to eliminate the pressure regulator. If you still have inadequate pressure, your fuel pump is on the way out. If you want a brand new OEM fuel filter, I will send you a brand new one for cheap, as I can't use it on my car.

Glyn M Ruck

Correct John - d1no's car will have the old US set up & location of items as you have listed. I would do filter first as it was the last thing disturbed. Check piping to filter for dirt or internal delamination.

d1no

Ok guys thanks for replies. As of yesterday I took the back seat out and all the insulation and cover and have been driving like that. Holy crap car is loud now. The pumps makes so much noise, fuel sloshing and just road noise. Its amazing how the insulation and back seat dampen everything.

Glyn on the noise I was asking about its not from the fuel pump area its more like a buzzing from the ecu/maf/air intake location. Could it be the supercharger when the car is turned off? I assume its normal maybe im just more sensitive to it now.

Also on a side note, temp has been in the high 50s and the problem is still there on startup so deff not temp related.

John I pmed u on the filter.

johnand

I like Glyn and a few others are VERY sensitive to noises and am in tune to very subtle changes in sounds. Up until it's demise, I NEVER could hear my fuel pump. When I replaced the fuel pump and fired up my car, WITH THE BACKSEAT AND INSULATOR PAD REMOVED, I still could barely hear the pump. The VDO pump in my car is EXCEPTIONALLY quiet.

The noise you are describing coming from the engine is probably the coolant recirculation pump. Mine was CLEARLY audible when I was troubleshooting the fuel pump. My wife kept saying she could hear the fuel pump, because she was mistaking the sound of the coolant recirculation pump running.

d1no

The fuel pump is not that loudd when the car is idling but as soon as I take off the noise gets louder due to pumps working, road noise etc. But I guess I will try out the fuel filter and then move on to pump.. I should be able to get away with just replacing the main one behind driver side right? Sender level pump should be fine right?

johnand

Yep, there is only one pump. All the W203's have senders on both sides. Your car has the sender and pump assembly on the driver's side.

pcy

Cars need one fuel pump and one fuel level sender unit. I wonder why MB put 2 fuel level sender units. Is the second fuel level sender unit supposed to be redundant? If one of the sender unit fails, the other will ensure we get the fuel level? If Mb wanted to cut cost of the car, they could have removed the second fuel level sender unit; I wonder why they didn't.

d1no

I thought it was to transfer fuel from one side of tank to other? Or maybe because MB likes to overengineer their stuff to complicate things

cpbeasley

ya the tank is damn near chopped in two thanks to the driveshaft tunnel that cuts right down the middle of it.

pcy

I think you are right (to transfer fuel from one side to the other).

Glyn M Ruck

2 senders to average the content of the two saddle tanks - it's overkill but it's a Benz. I think John has hit the nail on the head. I think you are hearing the coolant recirculation pump up front.

I'm pleased to hear that John's VDO pump is quiet - because the Bosch pumps make an angry little buzz that I am aware of - as is Chris Brown & others. My car's pump, like splinter's & John's, is on the other side of the car. Older US cars have it on your driver's side.

It certainly sounds (& measures) as though your fuel pump is having a hard time. Now we need to find out why - blocked filter/bad pressure regulator, strainer or piping. Or the pump itself. I have a horrible feeling it's the pump but let's go through the system in systematic fashion & fix it once and for all so you can get on with life.

johnand

Filter sent today via priority mail. Should be there by the end of the week. Hope that solves it.

d1no

What isn;t overkill on a Benz lol.. But ok the circulation pump makes sense since its just before the engine gets started. My pump makes a angry little buzz too I think, with the seat and stuff removed everything is very audible.

If the filter comes in by sat I will do that and report back with my fuel pressure and starting. I really hope my last fuel filter was somehow defective and this new one fixes it but it will probably turn out to be somethin more expensive . But thanks for helping guys

mlg

had a horrible time with engine sttering and dedcreaqse power aqnd occas stalling, added 3oz of stabil in 1/2 tank of gas and now runs like a freight train, prior to this i disconnected the battery, ran a bottle of techron thru tank, and cleaned maf, i could not beleive the results, but the proof is in the pudding good luck

d1no

OK whew I finally changed out the fuel filter with the one John sent me and holy crappp it was my 4 month old Purolator fuel filter that was causing all these problems. Once I replaced the fuel filter the fuel pressure shot back up and its at 55psi with the car running and stays there after i shut the car off. When the fuel pump is priming the fuel pressure doesnt drop either. I cant beleive a fuel filter could cause all this.. WORD OF ADVICE. DONT BUY PUROLATOR BRAND FUEL FILTERR. ONLY BUY THE OEM MADE IN GERMANY STUFF.

On a seperate note I got a Check engine light could that be from changing fuel filter?

BTW thanks alot John for selling me the fuel filter for a discount

johnand

Awesome news, glad I could help Glad you don't need a new fuel pump.

You have found what a lot of us have found, and non-OEM parts on these cars are not worth the hassle.

Should have not got a CEL from just changing the fuel filter. Grab an OBDII scanner, or stop by an autoparts store and have them scan it for you and post the code here, so we can figure it out.