2012 Mercedes C250 1.8l turbo - check fuel pressure
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2012 Mercedes C250 1.8L turbo
2012 Mercedes C250 1.8l turbo - check fuel pressure
My wife's C250 (120,000km) currently has trouble starting (sometimes). No check engine codes. Most times it will start perfect. Sometimes it will crank for 5 seconds and then give up. It used to have a P0340 code but that went away after I replaced the cam position sensor. Once the car is running it runs perfectly fine, great idle and normal acceleration.
Things I've done recently... replaced battery, new air filter, recent oil change, new air filter, removed and cleaned MAP sensor (with electrical cleaner), remove and cleaned throttle body.
Since the air intake system is clean I'm suspecting fuel delivery. But don't want to just start replacing parts.
From what I understand there is a low pressure fuel pump and filter located under the rear seat and a high pressure fuel pump on the rear of the engine. Is it possible to check the pressure for both of these? I was hoping to find 1 or 2 schrader ports I could hook a gauge up to so I can check using a tester.
I also have a OBDII reader and Torque Lite. Maybe these would give me fuel pressure readings?
My wife currently uses 91 octane fuel. But I'm also going to try a highest octane I can find (95?) and see if that helps.
And here are the readings using Torque Lite when the car is 1st started and idling.
Vacuum - 7.1 in/Hg
Timing - -17 degrees
Intake - 11 PSI
Intake (another gauge - not sure what the difference is) - 67 kpa
Vacuum (another gauge - not sure what the difference is) - 18.6 in/Hg
Richard
Things I've done recently... replaced battery, new air filter, recent oil change, new air filter, removed and cleaned MAP sensor (with electrical cleaner), remove and cleaned throttle body.
Since the air intake system is clean I'm suspecting fuel delivery. But don't want to just start replacing parts.
From what I understand there is a low pressure fuel pump and filter located under the rear seat and a high pressure fuel pump on the rear of the engine. Is it possible to check the pressure for both of these? I was hoping to find 1 or 2 schrader ports I could hook a gauge up to so I can check using a tester.
I also have a OBDII reader and Torque Lite. Maybe these would give me fuel pressure readings?
My wife currently uses 91 octane fuel. But I'm also going to try a highest octane I can find (95?) and see if that helps.
And here are the readings using Torque Lite when the car is 1st started and idling.
Vacuum - 7.1 in/Hg
Timing - -17 degrees
Intake - 11 PSI
Intake (another gauge - not sure what the difference is) - 67 kpa
Vacuum (another gauge - not sure what the difference is) - 18.6 in/Hg
Richard
Last edited by Richard Koop; Aug 11, 2019 at 08:12 AM.
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'14 ML350, '13 C220 CDI, '07 C280, '98 ML320
Typically, these cars have a valve at the end of fuel rail for checking fuel pressure. You should be able to attach a pressure gauge to that valve.
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Keep in mind that without an OEM specific scan tool, you cannot retrieve the MB specific DTC's. A P0340 is a code retrieved thru Global OBD2. I strongly suspect that you still have a cam adjuster problem; they tend to be intermittent at first and the CEL will come on/off. If you scan the car using a higher-end scanner, you may find a P034062 fault code.
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2012 Mercedes C250 1.8L turbo
Thanks for the info. I'll take a look.
Last time I had it checked their reader said it was the camshaft sensor. But after reading a lot and having it replaced, that can mean that your timing chain is loosening or the camshaft adjusters are going. Want to try to fix it before things go really bad. Just have to get the b*lls to do the job.
Richard
Last time I had it checked their reader said it was the camshaft sensor. But after reading a lot and having it replaced, that can mean that your timing chain is loosening or the camshaft adjusters are going. Want to try to fix it before things go really bad. Just have to get the b*lls to do the job.
Richard
