Hard starting / long cranking - fuel pressure regulator?
Thread Starter
MBWorld Fanatic!
Joined: Jun 2010
Posts: 2,755
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From: Emmett, ID, USA
2007 GL450
Hard starting / long cranking - fuel pressure regulator?
OK, MB wizards
About 10k miles ago, my 07 gl450 started cranking longer to start. This happened rather abruptly. It now takes 3 seconds or so to fire.
If I turn the ignition on, and wait for 10 sec before cranking, the engine starts quicker. Can't really tell but it seems about like it was before.
Not many comments on this out there, but it seems like this is a symptom of a leaking fuel pressure regulator - it releases the line pressure when the ignition is off.
If so, advice on replacement?
If not, where else to look?
About 10k miles ago, my 07 gl450 started cranking longer to start. This happened rather abruptly. It now takes 3 seconds or so to fire.
If I turn the ignition on, and wait for 10 sec before cranking, the engine starts quicker. Can't really tell but it seems about like it was before.
Not many comments on this out there, but it seems like this is a symptom of a leaking fuel pressure regulator - it releases the line pressure when the ignition is off.
If so, advice on replacement?
If not, where else to look?
MBWorld Fanatic!
Joined: Dec 2004
Posts: 4,268
Likes: 253
Your rail pressure needs to be read and determined if low/ rising slowly during crank, etc.
Too many variables to just say what is wrong with it
But I would start by pouring some chevron techron in the tank
Too many variables to just say what is wrong with it
But I would start by pouring some chevron techron in the tank
Thread Starter
MBWorld Fanatic!
Joined: Jun 2010
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From: Emmett, ID, USA
2007 GL450
I put in a bottle of Chevron fuel injector cleaner every 1k miles. Also about half my gas is Costco, which is Top Tier where i get it.
Thread Starter
MBWorld Fanatic!
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From: Emmett, ID, USA
2007 GL450
Pretty sure it's never.
Mostly it runs just fine, but there was recently a jerking / hesitating in the first 30 seconds of driving. Didn't recur.
I'll go pull OBD2 codes and see what's in there.
I'm seriously tempted to just throw parts at it, that is if the replacements are not too expensive. Couldn't find the pressure regulators online, tho.
Mostly it runs just fine, but there was recently a jerking / hesitating in the first 30 seconds of driving. Didn't recur.
I'll go pull OBD2 codes and see what's in there.
I'm seriously tempted to just throw parts at it, that is if the replacements are not too expensive. Couldn't find the pressure regulators online, tho.
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MBWorld Fanatic!
Joined: Dec 2004
Posts: 4,268
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dont touch it is my recommendation.
have somebody with star/ das take a peek at your fuel rail pressure during start.
dont throw parts at it. forget money- nothing is more disheartening than replacing a part and finding out that was not the problem.
have somebody with star/ das take a peek at your fuel rail pressure during start.
dont throw parts at it. forget money- nothing is more disheartening than replacing a part and finding out that was not the problem.
Thread Starter
MBWorld Fanatic!
Joined: Jun 2010
Posts: 2,755
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From: Emmett, ID, USA
2007 GL450
I ordered an icarsoft. Hopefully it will give me fuel pressure readings.
Thanks again. Always appreciate the wisdom. You once said, that truck ages well, and it's very true and has helped me through dark times.
Newbie
Joined: Apr 2016
Posts: 10
Likes: 2
From: SW PA
2011 GL550
Does it crank longer every time you go to start, or only XX% of the time?
Does it sound like it is cranking slower than prior to this happening?
I have had a couple random weird cranks on my rig and was more curious about what you are experiencing. Maybe I am slowly having this same issue. I would describe what I have as a noticeable slow crank compared to the normal crank. Almost seems like the engine has gotten way higher compression. Then, the other weird thing would be cranking really long without starting. I actually had that happen last night after fueling up. I would say less than 7 times have "odd" cranks happened in 5 months, so it is super random.
Does it sound like it is cranking slower than prior to this happening?
I have had a couple random weird cranks on my rig and was more curious about what you are experiencing. Maybe I am slowly having this same issue. I would describe what I have as a noticeable slow crank compared to the normal crank. Almost seems like the engine has gotten way higher compression. Then, the other weird thing would be cranking really long without starting. I actually had that happen last night after fueling up. I would say less than 7 times have "odd" cranks happened in 5 months, so it is super random.
Thread Starter
MBWorld Fanatic!
Joined: Jun 2010
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From: Emmett, ID, USA
2007 GL450
Sometimes it struggles to get through a rev. Then it picks up again. Overall, I'd say it's somewhat slower, but not by a big amount.
I have had a couple random weird cranks on my rig and was more curious about what you are experiencing. Maybe I am slowly having this same issue. I would describe what I have as a noticeable slow crank compared to the normal crank. Almost seems like the engine has gotten way higher compression. Then, the other weird thing would be cranking really long without starting. I actually had that happen last night after fueling up. I would say less than 7 times have "odd" cranks happened in 5 months, so it is super random.
I got the iCarSoft the other day, and I'll see if it can tell me anything about what's going on, and will report back.
Junior Member
Joined: Jan 2018
Posts: 23
Likes: 1
From: Toronto
2012 GL550
I'd say it's like 90%. There does not seem to be a consistent pattern. Sometimes it's slow to crank when it's been sitting for just a few minutes.
Sometimes it struggles to get through a rev. Then it picks up again. Overall, I'd say it's somewhat slower, but not by a big amount.
Sounds like we are having the same symptoms, just that mine are much more regular.
I got the iCarSoft the other day, and I'll see if it can tell me anything about what's going on, and will report back.
Sometimes it struggles to get through a rev. Then it picks up again. Overall, I'd say it's somewhat slower, but not by a big amount.
Sounds like we are having the same symptoms, just that mine are much more regular.
I got the iCarSoft the other day, and I'll see if it can tell me anything about what's going on, and will report back.
Thread Starter
MBWorld Fanatic!
Joined: Jun 2010
Posts: 2,755
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From: Emmett, ID, USA
2007 GL450
Nothing new. I never got around to researching whether I can view the fuel pressure. I'm distracted by what appears to be a failed injector.
The symptoms are now very consistent: Struggles on the first rev or two, then normal cranking for an excessive time (1-2 seconds) before normal start.
I suspect it is two problems: Low initial fuel pressure plus fatigued starter. I'll get the beast up and running and then change the starter.
The symptoms are now very consistent: Struggles on the first rev or two, then normal cranking for an excessive time (1-2 seconds) before normal start.
I suspect it is two problems: Low initial fuel pressure plus fatigued starter. I'll get the beast up and running and then change the starter.
Junior Member
Joined: Jan 2018
Posts: 23
Likes: 1
From: Toronto
2012 GL550
Thread Starter
MBWorld Fanatic!
Joined: Jun 2010
Posts: 2,755
Likes: 628
From: Emmett, ID, USA
2007 GL450
Nothing new. I never got around to researching whether I can view the fuel pressure. I'm distracted by what appears to be a failed injector.
The symptoms are now very consistent: Struggles on the first rev or two, then normal cranking for an excessive time (1-2 seconds) before normal start.
I suspect it is two problems: Low initial fuel pressure plus fatigued starter. I'll get the beast up and running and then change the starter.
The symptoms are now very consistent: Struggles on the first rev or two, then normal cranking for an excessive time (1-2 seconds) before normal start.
I suspect it is two problems: Low initial fuel pressure plus fatigued starter. I'll get the beast up and running and then change the starter.
Seriously, it's like in one revolution.
Newbie
Joined: Jun 2021
Posts: 2
Likes: 0
2011 ML350, 2011 C300, 2005 C230 kompressor
Thanks bro. When the parts are cheap, there is logic behind throwing parts at it. But you're right - the fuel filter & pump are like $400 for parts plus hours of labor. That's not a throwaway job.
I ordered an icarsoft. Hopefully it will give me fuel pressure readings.
Thanks again. Always appreciate the wisdom. You once said, that truck ages well, and it's very true and has helped me through dark times.
I ordered an icarsoft. Hopefully it will give me fuel pressure readings.
Thanks again. Always appreciate the wisdom. You once said, that truck ages well, and it's very true and has helped me through dark times.
Super Member
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From: San Francisco Bay Area
2006 R500
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From: Allentown, PA
'08 GL 320 CDI
