Longer than usual starting times....troubleshoot help.
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Joined: Nov 2007
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2015 ML350
Longer than usual starting times....troubleshoot help.
So my 2015 started to take a few seconds longer than usual to start. Always did it on the first crank or so with no hiccups. Now (sometimes) it takes a few extra cranks and few extra seconds. Also it seems to be more of an issue if it's cold and been standing for a while. If it was used recently, it will fire right up.
1) Tested the battery for low voltage. 12.55 volts. So that's not it.
2) Checked the OBD for codes, nothing. Not a single code.
So now I am not sure if something is *actually* wrong (or in the process of breaking down) or just growing pains now that's a few years old.
This is my wife's daily and I don't need it failing to start at the kid's school or something while I am away at work.
Any ideas?
Thanks
1) Tested the battery for low voltage. 12.55 volts. So that's not it.
2) Checked the OBD for codes, nothing. Not a single code.
So now I am not sure if something is *actually* wrong (or in the process of breaking down) or just growing pains now that's a few years old.
This is my wife's daily and I don't need it failing to start at the kid's school or something while I am away at work.
Any ideas?
Thanks
MBWorld Fanatic!
Joined: Mar 2004
Posts: 1,175
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From: Boston, MA
'14 ML350, '13 C220 CDI, '07 C280, '98 ML320
I am just thinking out loud here...
There is a check-valve in the fuel delivery system that ensures fuel pressure is maintained while the vehicle is just sitting there. If that check-valve is letting the pressure go while the vehicle sits for few hours, then, I can see how the startup can take few additional seconds while the fuel system is pressurized.
You can test and see if that is the scenario in your case. After the vehicle sat in the garage over-night, when you get in the car in the morning, put the key in the ignition (but don't start the engine), Turn the ignition to position 1 (instrument cluster lights up). Let the fuel system pressurize for few seconds, then turn the key to start the engine. See if you notice any difference in the symptoms of the problem you mentioned.
There is a check-valve in the fuel delivery system that ensures fuel pressure is maintained while the vehicle is just sitting there. If that check-valve is letting the pressure go while the vehicle sits for few hours, then, I can see how the startup can take few additional seconds while the fuel system is pressurized.
You can test and see if that is the scenario in your case. After the vehicle sat in the garage over-night, when you get in the car in the morning, put the key in the ignition (but don't start the engine), Turn the ignition to position 1 (instrument cluster lights up). Let the fuel system pressurize for few seconds, then turn the key to start the engine. See if you notice any difference in the symptoms of the problem you mentioned.
Thread Starter
Member
Joined: Nov 2007
Posts: 167
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2015 ML350
No dice. Started right up in the morning. Then later in the day tried to crank for a few seconds. And fine again later after that. Basically, when it's normal, it fires up on the 2nd crank when speedo is just starting to sweep up. When it has issues, it takes about 5-6 times, the same amount of time it takes the dash speedo and tach to sweep all the way up and back down.
MBWorld Fanatic!
Joined: May 2017
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From: Montreal/Cape Coral FL
2012 X6 35i Sport, 2013 ML 350 BT, 2019 4Runner TRD Pro, 2020 CRV-AWD
Dunno if this is pertinent on these german vehicles, but pcy is possibly on the right track.
I don't know if this is still the same, but on older American cars, they had a failsafe fuel-pump feed to the pump. This was in case the fuel pump relay took a dump. The symptom was longer cranking times before starting. It would take time for the oil pressure to build up in the engine, which then actuated a pressure switch which in turn fed 12v to the pump directly. If this is your scenario, could be that the signal to the fuel pump is intermittent, which would explain why sometimes it starts right up and sometimes not.
Just a thought...
I don't know if this is still the same, but on older American cars, they had a failsafe fuel-pump feed to the pump. This was in case the fuel pump relay took a dump. The symptom was longer cranking times before starting. It would take time for the oil pressure to build up in the engine, which then actuated a pressure switch which in turn fed 12v to the pump directly. If this is your scenario, could be that the signal to the fuel pump is intermittent, which would explain why sometimes it starts right up and sometimes not.
Just a thought...
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From: The Great White North
W204 C63 Coupe, W166 ML350 BlueTEC, 928GT, Taycan GTS Sport Turismo, C5 Z06 & IS300 race cars
No dice. Started right up in the morning. Then later in the day tried to crank for a few seconds. And fine again later after that. Basically, when it's normal, it fires up on the 2nd crank when speedo is just starting to sweep up. When it has issues, it takes about 5-6 times, the same amount of time it takes the dash speedo and tach to sweep all the way up and back down.
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Newbie
Joined: Jul 2010
Posts: 11
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From: Sydney Australia
Mercedes ML350, A170 and Vito
My ML350 Diesel W166 had this problem combined with sometimes not wanting to go into drive in the morning. Long story but replaced the main battery and all is well.
