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Lou P. master tech
Lou P. master tech, Mercedes Technician
Category: Mercedes
Satisfied Customers: 3739
Experience:  15 years master certified 100% fix rate and have access to factory radio codes, wiring, and instructions.
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2000 s500 200,000 miles. Cranks starts then shuts off. Runs

Customer Question

2000 s500 200,000 miles. Cranks starts then shuts off. Runs for 2-3 seconds....if I play with the throttle pedal and turn key on and off it will sometimes run fur about ten seconds. I hear the fuel pump. I haven't checked fuel pressure.
Submitted: 3 months ago.
Category: Mercedes
Expert:  Lou P. master tech replied 3 months ago.

Hello, my name is***** and i will do my best to assist you.I am going over your story now and will reply back soon with some info,thanks!

Expert:  Lou P. master tech replied 3 months ago.

Ok John, well the first thing i need to know it , what is the fuel pressure when the key is first turned on, and how long does the fuel pressure remain when the key is turned off, do you have access to a fuel pressure gauge? and also when the car does run, does it run good or bad and misfire ?

Customer: replied 3 months ago.
I will have to borrow a fuel pressure gauge and get back to you....it sounds good when it does run.
Expert:  Lou P. master tech replied 3 months ago.

ok good deal, so heres what we need to do to save some back and forth

Expert:  Lou P. master tech replied 3 months ago.
  1. connect fuel pressure gauge to tip of rail on front of passenger side of engine
  2. with key on the pump should build pressure above 55psi
  3. if the pump does not build that much pressure then i suggest you pinch off the hose on the fuel filter that is the return line to the tank, the fuel filter has 4 lines,, the feed line from the tank on the bottom of the filter and then the output , those are about the same size, then it has a smaller line in the center of the filter on the output side that is the vacuum for the internal pressure regulator, at the opposite end is the return to the tank, if you pinch that off and pressure skyrockets then the fuel filter is the issue if it does not then the fuel pump is the issue,, i may have my lines crossed but you should be able to tell by following the lines and the arrow on the fuel filter. arrow points toward engine so the line we need is on the opposite end.
  4. if pressure does not change then the fuel pump is the issue

let me know if this helps and if you need more help, i will be available most of the day . Please take a second and click the STARS above and rate my service 4 or 5 stars if you feel I have been helpful and please request me in the future. Keep in mind that when you rate it does not end our conversation, you can still return here to me for follow up information if needed, Thanks for choosing just answer. Also , if you feel i deserve one , BONUSES are GREATLY APPRECIATED! Thanks again , Lou P.

Customer: replied 3 months ago.
The fuel pressure does not build with the key in the run or on position. When cranking and while the engine is running fuel pressure is 55psi plus. The engine dies and fuel pressure remains 55 slowly dropping .
Expert:  Lou P. master tech replied 3 months ago.

Ok that sounds good so far. Next thing I would do is unplug the mass air flow sensor and see if the car still runs. Keep in mind it will set off the check engine light but won't hurt anything. The mass air flow sensor is the big plastic intake pope that the air filter housing connects to. It has a 5 pin connector they plugs on the side of it.

Customer: replied 3 months ago.
That's actually one of the first things I did. It did not change anything...check engine Light already on. My scan tool won't read the Benz ecm. I'm not a mechanic, but I have done some GM ls swaps into jeeps.. I have some experience with trouble shooting
Expert:  Lou P. master tech replied 3 months ago.
Ok cool sounds good. Next step is to loosen the exhaust off the manifolds. There are only 2 bolts per side. So loosen them enough to get some space between the manifolds and the exhaust pipes. Let's make sure the exhaust is not clogged. Since you can feather the throttle and it stays running tells me they the engine is healthy. It's a issue that is affecting airflow in or out. Or fuel injection control.
Customer: replied 3 months ago.
It does not stay running by feathering the throttle. If i give it throttle while the key is on and then start it , it Just runs a little longer maybe 10 seconds instead of three. It does not run long enough to attempt to give it any throttle ....also when it starts the exhaust note/sound sounds very good. It was running and driving one day. Then nothing the next are you thinking clogged catylitic?
Expert:  Lou P. master tech replied 3 months ago.

it can be a clogged exhaust, the internals loosen up and can jam into the pipe causing a clog, so to rule that out we loosen the exhaust at the manifold to allow air to escape and see if it helps .

also do you have any fault codes?

Customer: replied 3 months ago.
Can't read the codes with my tuner/scanner....my scanner doesn't recognize the Benz ecm
Customer: replied 3 months ago.
Will I need new gaskets if I pull the manifolds away from heads?
Expert:  Lou P. master tech replied 3 months ago.

you must have not read my post correctly................. we are loosening the pipes from the manifolds, 4 bolts total, 2 bolts on each side, NOT the manifold to the head.

Expert:  Lou P. master tech replied 3 months ago.

any luck?? i have not heard from you ?

Customer: replied 3 months ago.
No. Room in my shop right now. I will keep working on it when i CAN. Let you know
Expert:  Lou P. master tech replied 3 months ago.

ok Jay, let me know when ready Please take a second and click the stars at the top of the screen to rate me so i may receive my credit , 5 stars is ideal , please request me in the future.
Keep in mind then when you rate it does not end our conversation. you can still return here to me for follow up information if needed, Lou P.

Customer: replied 3 months ago.
I was just trying another scan tool with no luck.....but I did discover that the engine does stay running if I feather the throttle...exhaust smells bad like rotten gas. Then it spits and sputters and dies. Fires right back up.
Expert:  Lou P. master tech replied 3 months ago.

ok did you loosen the exhaust at all?

Expert:  Lou P. master tech replied 3 months ago.

next is, do you have a machine that we can run the engine off of, so we can rule out fuel? also get a fuel sample.