S-Class (W221) 2007-2013: S 320 CDI, S 350, S 450, S 500, S 550, S 420 CDI, S 600

Blown Fuel Pump Fuse

Old May 22, 2011 | 06:22 PM
  #1  
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S550 4MATIC W221, W222, Lotus Elise
Blown Fuel Pump Fuse

Car stalled while driving on the local road. Turned out to be a 30A fuel pump fuse blew (Fuse #118), benind the rear seat armrest.

Replaced fuse and car started up. After few miles driving fuse blew again. Now I'm thinkng there is something wrong and car is not safe to drive.

Could be fuel, pump, wire or relay caused this? If you had same issue before, please share the fix.

Also, does anyone have pump replacement procedure / diagram? Car has 39k mile on the clock and out of warranty.

Thanks

Last edited by mb1000; May 22, 2011 at 10:03 PM.
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Old May 23, 2011 | 06:38 AM
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Originally Posted by mb1000
Car stalled while driving on the local road. Turned out to be a 30A fuel pump fuse blew (Fuse #118), benind the rear seat armrest.

Replaced fuse and car started up. After few miles driving fuse blew again. Now I'm thinkng there is something wrong and car is not safe to drive.

Could be fuel, pump, wire or relay caused this? If you had same issue before, please share the fix.

Also, does anyone have pump replacement procedure / diagram? Car has 39k mile on the clock and out of warranty.

Thanks
IMO that's a safety issue that should be addressed immediately by someone who knows what they're doing.Unless you're a true expert this isn't a DIY job.
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Old May 23, 2011 | 09:35 PM
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Originally Posted by listerone
IMO that's a safety issue that should be addressed immediately by someone who knows what they're doing.Unless you're a true expert this isn't a DIY job.
You are right, it is a safety issue. It's like a car ran out of gas when fuse blew and I had to apply brake harder to stop the car. I'm not going to drive the car till it is fixed

After replaced another 30A fuse, the car runs fine from test drives. There is no code or message there. The problem now is how to reproduce the issue. I tested that the current is around 9-10A at 2-4000 RPM now. I can use my engineering background with some help or bring car to dealer if issue reproduceable.
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Old May 25, 2011 | 09:12 PM
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Update

Looks like this is not a common problem as there is no response with same issue.

I got feeling that bad gas can be the cause (water, particles, etc).

I ran car at idle and burned all gas. Bought a pack of 30A fuses, filled up with different brand gas, drove 200+ miles without an issue. It is still hard to tell though. If fuse blew, I can prove the problem still there but not the other way around.

Searched internet and there were some reported issues. After replaced fuse, their car run for 2+ years and do not have problem. Anway, move on and prepare for stop.
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Old May 26, 2011 | 03:53 AM
  #5  
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Originally Posted by mb1000
Update

Looks like this is not a common problem as there is no response with same issue.

I got feeling that bad gas can be the cause (water, particles, etc).
You don't say if the steps...and conclusions...you've specified were done/reached by an expert (dealer,Indy shop) or by you.I hope it was the former.However I,a non-expert to be sure,am having trouble imagining "bad fuel" causing a fuse to blow....more than once.

Well,hope things are now back to normal.
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Old May 30, 2011 | 07:21 PM
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Blown Fuel Pump Fuse - found problem

After I opened the cover of the fuel tank where fuel pump is in, I found there are wires to the fuel pump and the red one got cut! I can see the burning marker on the wire.

That's it. There is a very sharp edge on the top portion in the fuel tank where wires go through. If I keep driving the car, sooner or later the fuse will blow again and can catch fire.

I made a quick fix by routing wires through a gas resistant plastic pipe and rerouted wires a little bit. Feel much safe now.

I think this is definitely a design or manufacturing issue and should warrant a recall. Don't know how many W221 out there like this.

I took good pics and will send to MB and report to NHTSA.

Last edited by mb1000; May 30, 2011 at 07:36 PM.
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Old May 31, 2011 | 02:52 PM
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Originally Posted by mb1000
I took good pics and will send to MB and report to NHTSA.
This,IMO,is clearly a serious safety issue and if yours wasn't a "freak" occurance then a mandatory recall certainly could be called for.
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