Shawn K

I just checked the fuel pressure , it shows 37PSI,
and as soon as I turn off the car, pressure gauge drops to zero,
I have these problmes too :
1- I have hard start problem , it takes unusual time to start
2- My Car shuts off with half gas tank . replaced both fuel pumps, may be related to fuel pressure in tank.

Please let me know if you have any idea.

mlee1951

I never had any problems with the fuel level......most of the time, I run the gas tank down to 1/8th. of a tank or the gas warning light comes on. Since it is not winter, the car runs perfect. BTW, the dealer did mention that the MAF needs to be replaced, I had the mechanic clean the MAF, rather than replacing it for less than $50 bucks.

Shawn K

your problem It should be fuel filter, cheapest way to start for diagnose.
my problem is really complicated.

Shawn K

please check fuel pressure in fuel lines.

mlee1951

one of the first thing my mechanic checked was the fuel pressure.....he didn't notice any drop during the overnight test. he chalked it up as a lazy fuel pump. someone mentioned that they had the software updated and it resolved their problem. when i brought my C240 back to the dealer, i asked them to check for updates......which i doubt they even looked.

mlee1951

If you found a solution, drop me a note. thanks....
My 2004 C240 will be hassle free for another 4 months or so. Then I will start adding a fuel cleaner (Sea Foam) to the tank every month or so. It seems to help.

mlee1951

BTW, when I serviced the car when this cold start problem surfaced, the fuel filter was changed, along with new plugs, fluids, and replacing the Crank Position Sensor plus the Cam Sensor.

I am thinking it has to do something with the winter blend gas. I even tried all the top tier gas and it didn't help. Only during the cold winter months is when I have a cold start problem. During my last service about 6 months ago, I had the mechanic clean out the MAF.

Khris999

I left my car parking for about 3 weeks,

When I returned from where I had gone, the car started as normal. I drove about 10km, and stopped to get something at a Mall. I got back and hopped into the car I tried starting but it kicked and Rev didn't come up, tired so many times with no avail. I had to put on neutral and rolled it yo tat starting, it eventually started. But the next day, same problem, the car rushed starting. I went online and came across ur post.


To cut the story short, I almost removed my fuel pump and filter, I even cleaned the fuel nozzle but no change happened.

Some Auto electrician traced and found the prothem to be from the fuel control module under the right rear passenger seat. It had some corrosion in the terminals and preventing the pump from working well. The terminals were cleaned and car started immediately.

mlee1951

Thanks for the suggestion.....nobody seems to know why during the winter months, I have this cranking problem. I have suspected that the winter blend gas had something to do with it because this long cranking problems only occurs during the cold winter months. During the spring, summer and fall months, the 2004 C240 runs fine.

Even at the MB dealer, the mechanic was guessing the fix......and no guarantee the fix will resolve the problem. I wasn't going to spend a few thousand dollars on guess work.

paulzale

Any updates on this issue? I am having similar cold start problems.

Car will crank over, engine stumbles a second or two during the starting cycle. I have been able to get it to start by tapping the throttle pedal a few times during the next cycle and the car will start. After car starts, its good for the day. If temp is colder, below 30F, it does the same thing only working the pedal won't help get it to start. I did notice the smell of fuel (which makes me believe it is flooding the engine). So I pulled the fuel pump fuse and tried again, it fired up immediately and ran for a moment then died (used up the fuel in the rail). So I inserted the fuse again, primed it, pulled the fuse, it fired up and I quickly put the fuse back in before it could die. Car runs fine all day, on off, etc. until next overnight cold situation. I've got a temp sensor, but the gauge and the digital readout seem to be accurate.

mlee1951

The 2004 C240 problem never went away.......I can only suggest adding a bottle of Sea Foam to the car every 2-3 fill-ups, it helps during the winter months.

paulzale

I've been using Techron and Seafoam about 1/month without resolution. This is very odd in that the system floods when cold and can be resolved by removing the fuse, starting, then quickly putting fuse back in. I will change the temp sensor to see if that resolves the issue, but very very odd, especially after getting going in morning I can leave it sit for several hours and it restarts no issue!

mlee1951

Please give me an update if the temperature sensor replacement helps. Thanks.

paulzale

Was a pain to change, only because it is a 17 year old car and the old one was stuck in the hole! The old sensor was also brittle and the plastic crumbled as I was unplugging the connector, so I was hopeful, but unfortunately it didn't solve the hard starting issue. I will be replacing the EGR soon and resetting that code, when I do, I'll update here.

mlee1951

Thanks.......amazingly, no one can point the finger to the cause for the cold "winter" start issue. Even the mechanic at the MB dealer is just guessing.

paulzale

Yes, I spoke with a mechanic and he said this was VERY uncommon and didn't have any thoughts beyond what has been discussed in this thread. I asked about the ECU thinking it has E85 and he said that is more common in newer models, but I'm wondering now. I've never used E85, but maybe winter gas confuses the ECU? Grasping at straws now.....

paulzale

I have changed the EGR and all CELs are gone, car runs great and no other issues other than first "cold" start in the morning. Pumping the pedal doesn't work consistently, but what does is removing the fuel pump fuse and the car fires up. I need to quickly reinstall the fuse within a few seconds or car dies, then I repeat until started. Once engine warms it will start consistently all day long even if left a few hours. I am thinking it maybe the length of time the car is left sitting vs temperature, but it isn't warm here yet.

paulzale

OK, still having the starting issue, seems to happen under 70 degrees. I get a CEL every now and then for P0172 and sometimes P0175. I clear codes and they don't come back for a while, but will pop up randomly. I know this is a rich condition, primarily bank 1 and sometimes (rarely) bank 2. I change the MAF to a new bosch unit from FCP Euro and new air filters. Still not fixing the issue. Any thoughts? injector(s)?

tkid

I had a similar issue on a turbo sports car many years ago. I had to remove the fuel pump fuse to get the car started!
It turned out to be corrosion on the temperature sensor terminals in the engine bay. The corrosion increased the resistance the ECU was reading, making it think the engine temp was -50'C! Hence, flooding the engine when trying to start!
Once the terminals were cleaned, it started no problem.
I would suggest checking the terminal connections of all temp related sensors.?
Do you have an OBD reader, that would help identify if any unusual temp readings are being made?..
Also, maybe try giving the fuel injectors a clean out, if that hasn't been done recently?..

paulzale

I changed the temp sensor 6 months ago. ObdII scan has no temp related issues I can see, dash Guage seems accurate for temp. I get P0172, which is bank 1 rich. I'll check all temp sensors again and clean. Leaning toward injectors or O2 sensor???

tkid

Did you replace anything around the engine before this started happening?..
I would check all connectors for signs of corrosion. Spray some electrical cleaner just to ensure good connectivity?..
Worth cleaning out the injectors as well, if that hasn't been done before?..
How old are the oxy sensors?

paulzale

Hard start issue started last spring.
Got worse this fall, changed temp sensor, no change.
Long time check engine light for EGR.
Replaced EGR 2 months ago, CEL went away for a few days. Came back with P0172 and P0175.
Changed MAF and Air filters. CEL stayed off a few days.
CEL came back w P0172.
Runs fine, can clear CEL and will stay off for 3+ hours Highway drive or around town then will pop up randomly.
Still hard/no start in morning unless I remove fuel pump fuse. Will start fine rest of day after running 5 minutes from initial start.
Car is 2004, 190k miles, O2 sensors original.

tkid

Did you check all the hoses feeding into the EGR valve? Possibly congested with carbon build up?..
The oxy sensors are quite old; could be suspect as well?.. at least remove them, inspect and clean?..

paulzale

All hoses feeding EGR were replaced or cleaned, dumped 2 bottles of fuel injector cleaner into tank and drove on highway 3 hours yesterday. Will monitor and move to 02 sensors next then injectors themselves if not resolved.

paulzale

Finally got around to replacing injectors as I believe those (driver's side) are leaking down causing the hard start and rich condition on bank one. It wasn't hard to replace, but a little bit of a pain, clips on injectors are "tight" to get on and off with those metal clips. Fuel rail with injectors are "tight" in the intake due to age +/-18 years! Two of the plastic/composite o-ring retainer clips on injectors fell off (I used a scope to look in the intake without seeing them). Decided not to take off the intake and take my chances. Easier start this morning, no CEL, will monitor and report if this solved the issues. Also, took a while to start after reassembly with a lot of CEL codes, remember there will be a lot of air in the fuel lines that has to be displaced.