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Crank But Won't Start - Going Crazy...

Apology guys, I had to start a new thread on this topic since others are a bit old.

My car C240; W203; 2002; Odometer reading: 205,000 miles. Next A Service, at least 5,000 miles.

Last week without warning the car stuttered on the freeway, started to stall. I cleared to the shoulder, the car failed completely. It cranked but refused to start. Warning light displayed alternator not charging. So I towed car home. Jump-started with powerful battery charger, car cranked but still refused to start. Here is a timeline of parts I replaced:

1. New alternator replacement - 2 and half years ago (professional installation)
2. Replaced Crankshaft Position Sensor (Bosch) - exactly 1 yr ago - from Amazon
3. Replaced Serpentine belt - exactly 1 yr ago
4. Replaced Belt Tensioner - exactly 1 yr ago
5. Replaced Belt Idler Pulley - exactly 1 yr ago
6. Replaced all 12 spark plugs (Bosch) - 4 yrs ago (Average 7k miles/year since replacement)

After car failed on freeway last week, I did the following:

1. Checked alternator, pulleys, belt tensioner, battery, all ok - last week
2. Replaced serpentine belt again, anyway - last week
3. Cleaned MAF sensor with professional MAF sensor cleaner - last week
4. Installed new Fuel Pump - yesterday
5. Tested Schrader valve with Injection Pump Pressure Tester, passed at 55-60psi - tested yesterday.

I should mention here that car initially did not start even with new fuel pump, until I added more fuel to tank from 1/8 to quarter tank. Fuel pump tester also showed zero pressure reading before I added more fuel.

Car started today, I drove only three miles, car sputtered and died again in front of Walmart. Crank pretty good but no start. Towed car home again, second time in one week. Here's what I did today when I got home:

1. Tested Schrader valve with pump tester, zero pressure reading.
2. Poured small quantity of gas directly into MAF sensor opening, car started, ran for a few seconds, then cut out.
3. At ignition position 2, fuel pump initiates for a few seconds, then stops.

I am at my wits end. What is the problem? Car is too old to take to dealership and spend gazillion dollars. I did everything above by myself, except alternator replacement done by a certified Benz mechanic. I bought iCarsoft MBII OBD scanner and scanned for codes, but I'm still learning this scanner and can't decipher the numerous codes. There's no code specifically for fuel system, or at least I can't tell. How do I test or read fuel-related codes on this gizmo?.

Can anyone tell me what's going on with the car? Much appreciated, thanks!. So so sorry for the very long statement.
 

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2. Replaced Crankshaft Position Sensor (Bosch) - exactly 1 yr ago - from Amazon
These are classic symptoms of CPS failure. I would never buy name-brand critical parts from Amazon or eBay - there are a lot of fake parts for sale on those sites.
 

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These are classic symptoms of CPS failure. I would never buy name-brand critical parts from Amazon or eBay - there are a lot of fake parts for sale on those sites.
Thanks... Would you know of a credible source for Benz OEM parts?
 

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The OP already said that he tested the fuel pressure and it was zero. Pouring gas in the MAF got it runninng and then died. Plus he just recently replaced the CPS with a Bosch unit (same thing FCP sells). In my mind he's already proven the CPS is in working condition.

Moving on to solving the real issue here. This model is know for electrical issues with the fuel pump. There are a couple of areas where the wires will burn. There are 2 fuel pump senders, one on each side of the fuel tank. Lift up the bottom of the back seat and check the condition of all the connectors. The problem will be very obvious when you find it. One of the connectors will be burnt. Also check the connector at the fuel pump. Let us know what you find.
 

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The OP already said that he tested the fuel pressure and it was zero. Pouring gas in the MAF got it runninng and then died. Plus he just recently replaced the CPS with a Bosch unit (same thing FCP sells). In my mind he's already proven the CPS is in working condition.

Moving on to solving the real issue here. This model is know for electrical issues with the fuel pump. There are a couple of areas where the wires will burn. There are 2 fuel pump senders, one on each side of the fuel tank. Lift up the bottom of the back seat and check the condition of all the connectors. The problem will be very obvious when you find it. One of the connectors will be burnt. Also check the connector at the fuel pump. Let us know what you find.
It makes sense that since car can start with little gas poured in MAF, CPS is unlikely to be the cause. Zero fuel pressure seems to point at fuel circulation system as the problem. However, I've just checked both connectors on each side of tank, no burn signs are visible. The connector at fuel pump itself is also ok - it purrs at ignition position #2.

I've checked all fuses in the system - all ok. Only thing remaining to do with fuel line is filter replacement, which has never been done. I wonder if bad filter can fail gas supply to engine. In another forum, someone suggested that since I changed out fuel pump, there may be huge air pockets somewhere and I need to fill up tank to max. This is hard to do with car disabled.

Next, I'm replacing fuel filter this afternoon since it's long overdue anyway. I also have a spare Bosch CPS as a last resort. Will be back.
 

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Have you tested to see if power is being applied to the fuel pump? Also be sure to check the ground wire too. I've seen those fry as well. Remember to be careful because you're working around gasoline and you don't want any sparks to happen
 

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My belief is that if and when the CPS fails to send a signal when the engine is cranking ,the ECU will stop sending power to the fuel pump.

Check for code P0335. Bad Crank Position Sensor.

If the one you bought was a fake it could be faulty..
 

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Check fuel pressure on the rail when initially turning the key to position 2. If you have pressure then, but it drops to zero when cranking, then it's most likely the CPS. And just because a CPS is sold as "Bosch" does not make it so. I think many of the Bosch labeled parts on Amazon and eBay are fakes.
 

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Check fuel pressure on the rail when initially turning the key to position 2. If you have pressure then, but it drops to zero when cranking, then it's most likely the CPS. And just because a CPS is sold as "Bosch" does not make it so. I think many of the Bosch labeled parts on Amazon and eBay are fakes.
At position 2 fuel pressure is 0. Also 0 when cranking, needle does not move at all. I replaced fuel pump relay at rear SAM, no luck. Getting ready to change out CPS today.
 

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My belief is that if and when the CPS fails to send a signal when the engine is cranking ,the ECU will stop sending power to the fuel pump.

Check for code P0335. Bad Crank Position Sensor.

If the one you bought was a fake it could be faulty..
I have an iCarsoft MBII OBD, have navigated the entire menu but can't figure out how to test CPS or fuel system. So I chose comprehensive diagnostics of all components and tried to read through entire results, still no luck. A search for P0335 in onboard library simply describes how CPS works, but not how to diagnose or test it using the device. Sucks.
 

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Have you tested to see if power is being applied to the fuel pump? Also be sure to check the ground wire too. I've seen those fry as well. Remember to be careful because you're working around gasoline and you don't want any sparks to happen
All visible connections are ok, unless it's fried somewhere hidden. I changed out relay at rear SAM, no luck.
 

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You should have fuel pressure at position 2,,ignition on ...even with a bad CPS. So maybe the CPS is ok ...

Have you replaced your fuel filter yet ?

Any check engine lights ,,? a basic scan for errors should show P0335 if it was bad,,,

I would also put more fuel in the tank ,,use a jerry can.
 

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It most likely cannot be a problem with the CPS. He already proved it works by pouring fuel into the intake and starting it up. Your confusing him with this bs about the CPS, so please stop that and let's keep this thing on track. Often times this type of problem is caused by the owner not changing the fuel fiter and it puts extra stress on the pump and wiring. Don't get ahead of yourself and start guessing. It's usually something very simple and easy to fix.

Did you actually use a multimeter to test for 12 volts at the pump itself while trying to crank it? Also, use a multimeter and test for continuity to make sure you are getting good ground at the pump too! I've seen either of these as a problem on some W203's. Don't skip these steps because it might cause a lot of heartburn and later on you'll wish you had done it. Buying a good multimeter is a good investment if you don't already have one. It will pay for itself in no time.
 

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If you have power and ground to the pump and still no fuel. Try loosening the input to the fuel filter, turn on the ignition. If no fuel sprays out you need a new pump, if it only drips out there is not enough pressure to get through the filter.
 

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It most likely cannot be a problem with the CPS. He already proved it works by pouring fuel into the intake and starting it up. Your confusing him with this bs about the CPS, so please stop that and let's keep this thing on track. Often times this type of problem is caused by the owner not changing the fuel fiter and it puts extra stress on the pump and wiring. Don't get ahead of yourself and start guessing. It's usually something very simple and easy to fix.

Did you actually use a multimeter to test for 12 volts at the pump itself while trying to crank it? Also, use a multimeter and test for continuity to make sure you are getting good ground at the pump too! I've seen either of these as a problem on some W203's. Don't skip these steps because it might cause a lot of heartburn and later on you'll wish you had done it. Buying a good multimeter is a good investment if you don't already have one. It will pay for itself in no time.
Finally changed fuel filter (and that was no fun). Still crank but no start. So I bought a multimeter and tested everything from relays to fuses and connectors. Fuel pump relay tested ok. So I opened up fuel pump compartment again to test voltage to pump while cranking. I got 10.5 volts, maybe due to all the cranking. Continuity also ok.

But I noticed that a supply hose had come off the fuel pump. The hose is a supply line from inside the tank connecting to a valve on top of new fuel pump. I suspect it's because the valve is top center of new fuel pump and does not have a direct alignment with hose slot running along its side, which would enable hose to fit snugly into pump valve. This misalignment created a pulling force that separated hose from valve, probably when I test-drove car with new pump. The old pump that came with vehicle is properly aligned. See attached picture.

So, I'm returning new fuel pump and getting another brand, Bosch. Additional cost of using after-market fuel pump: $65 in towing costs, hours of labor, one week without a car (so far). I will update when new pump is installed.
 

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Hello!

I have the EXACT same issues with my c-class sport coupe 220 cdi , i have no clue where to begin with, the car never stalled while running though it cranks and doesn't start anymore (it always took some revs cranking before starting but now it's plain dead ...)
No warning lights on dashboard, and no dtc's pointing to CPS, i don't know even where to begin with, but since i have no idea when filters were last changed i think i'll go from there...

It scares me to hear you have done so much and no luck yet, so if you see the light, please give me some hope, i'm getting desperate working on foreign country and stuck with no car to move arround, and not much of tools and knowledge...

Thank you, good luck!
 

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Hello!

I have the EXACT same issues with my c-class sport coupe 220 cdi , i have no clue where to begin with, the car never stalled while running though it cranks and doesn't start anymore (it always took some revs cranking before starting but now it's plain dead ...)
No warning lights on dashboard, and no dtc's pointing to CPS, i don't know even where to begin with, but since i have no idea when filters were last changed i think i'll go from there...

It scares me to hear you have done so much and no luck yet, so if you see the light, please give me some hope, i'm getting desperate working on foreign country and stuck with no car to move arround, and not much of tools and knowledge...

Thank you, good luck!
Sure will let you know. I've just ordered a Bosch fuel pump. I hope yours will be less hassle to fix.
 
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