1995 c280, engine cranks, cranks, cranks and cranks but does not fire in the morning. it starts after 4-5 attempts, each attempt with waiting at key position 2. when it starts, it drives perfect like, well, benz. never any problem with warm start. warm start always on first attempt. changed ovp relay, no relief. changed camshaft position sensor, no change. changed fuel filter, no difference. my next step is to get fuel pump changed by mechanic. anything else, i need to do prior to fuel pump change??

no cel, went to autozone and scanner revealed 2 codes - P0400 Exhaust gas recirculation flow malfunction and P0505 Idle control system malfunction. today is the first time i had appropriate experience with cold start after egr valve cleaning yesterday. i recorded in mp3 format. http://www.youtube.com/watch?v=WDrQCmD3tio first sound is when i wait at position 2 (first 4 seconds) second sound comes from passenger side rear end that starts at 7th second into this audio clip and ends at 10th second. sometimes i don't hear second sound. car does not start if second sound is absent. at this moment i have no idea what these sounds mean. hopefully, some of you will be helping in this regards.

Put in a new fuel pump relay?

__________________
1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra

hello vaidlookman,

before you start throwing parts at your benz, if i were you , i would do some research on this forum. there's a ton of information, along with good people who are willing to help , just be patient, and i'm sure you'll resolve your problem.

for starters, your benz has the M104 engine with the 2.8L displacement. your engine(M104 2.8) and the M104 3.2L are essentially the same engines, i'm pretty sure the only difference between the two engines is that they have different displacements. So, any info that you find on here regarding the M104 3.2L pertains to your engine as well.

Check out the following link (it be smart to add this to your favorites): http://www.peachparts.com/shopforum/showthread.php?t=219192&highlight=m104

Although your benz is not suffering from a missfire, there are a series of tests provided by Mr. Dalton which can be of much use to you.

I would take a close look at page 1, post#6:

" But fuel pressure is a next step.
On the top of the fuel rail, you will see a test port cap..That is where you can hook up a gauge. That fitting is the same as an R12 fitting, in case you do not have one.
So, first check is to start the engine and let it idle..now, pull the vac line at the regulator and see if any gas is shooting out that port on the reg. There should be none and if there is, the diaphragm is leaking and you need a new regulator. [ raw, unmetered gas getting sucked intio intake.]. Also check for any evidense of fuel in that vac line..again, you want none.
If all is well, then hook up gauge and do this simple 3 part test.
1-Engine @ idle, Vac line ON-- FP should be 3.2-3.6 Bar
2- " " , Vac line OFF-FP should jump to 3.7-4.2 Bar


3-Engine OFF , wait 30 min. -FP should maintain at least 2.5 Bar
*** I believe if it fails this test, your check valve may be failing. The job of the check valve is to maintain the fuel pressure between the fuel rail and fuel pump*** NOTE: the red text, is info i have added, and i might be wrong, so do the research

*Bar = 14.5 PSI... [ you already know that, but this winds up in archieves]"

Sorry for the long post, but hope you find at least some of it useful.

good luck

thanks for the suggestions
yesterday, i cleaned maf, egr switchover valve, and idle rasonance valve. no difference. idle @ 1500, i can live with it for now, but cold start problem is my concern. i have apptt scheduled with independant mechanic who will charge me $35 to check fuel pump, vac lines, and diagnostics. and $85 to replace fuel pump, if needed. i will keep updating, so that other forum members can benefit from my experiences.

3 attempts this morning, and car started at idle 1200. runs smooth, no misfire, no stalling at stop sign, no idle up and down. this morning, i disconnected vacuum line from fuel pressure regulator, idle increased a tad bit and engine sound changed. when connected, engine sound changed back to normal, ie fuel pressure regulator is ok. i am learning from this forum.
thx timmyr and mpolli

helllo again,

i recently checked out your youtube video, and noticed that you mentioned the sound heard (enhanced) from 7 to 10 seconds coming from the rear passenger side. this sound is most likely your fuel pumps.

under your youtube video you mentioned that the car does not start when you do not hear the sound from seconds 7-10 of the video. like mpolli suggested earlier, before you replace the fuel pumps make sure that your fuel pump relay is properly functioning.

good job with egr fix.

i didnt understand what you meant by "car started at idle 1200." how does the idle behave after the engine has warmed up? do your rpms still stay above 1000rpms?

For the record you can test the fuel pump relay theory by jumpering around the relay. But I don't usually mention it since people seem to find it to be mind boggling and would rather just buy a new one.

__________________
1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra