Fuel pump fault - Mercedes Benz SLK Forum

SLK R170 General Discussion SLK 200, SLK 230K, SLK 320, SLK32 AMG

 
LinkBack Thread Tools
#1 Old 10-15-2012
Registered Users
 
Join Date: Jun 2012
Location: Norfolk England
Vehicle: SLK 200 R170
Other Toys: Triumph Tiger 1050, Teal type 35
Posts: 23
Country:
Chats: 0
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 4
Thanked 4 Times in 4 Posts
(Thread Starter)
Fuel pump fault

Hi All,

I have a 2003 200K with 80,000 miles.

I have searched and forgive me if I have missed any previous posts.
I am having severe power loss intermittently when the car gets hot. My immediate feeling is that the engine is starved of fuel. I have done the relay solder check and made good suspect joints.
The problem occurs when the engine is at max temp, i.e. when travelling in slow traffic and the fuel tank is 1/4 full.
I have also noticed that when the power loss happens the fuel pump is noisy and the noise sounds as if the pump is changing speed.
I have read elsewhere that the pump is cooled with the fuel in the tank and I can see that with a small amount of fuel in the tank, the exhaust hot under the car and little or no airflow under the car, the return fuel hot from the engine the heat can soon build in the tank.
I suspect if the pump is on it's way out the heat could cause it to partly seize or run slow. Has any one else had pump problems?
byjingo is offline  
Sponsored Links
Advertisement
 
#2 Old 10-15-2012
Administrator/Founding Member

 
jbanks15's Avatar
 
Join Date: Jun 2006
Location: Tampa, Florida
Vehicle: 2009 SLK 55 AMG Kleemann Supercharger, ECU tune, Headers and LSD, CF Diffuser
Posts: 91,141
Country:
Chats: 38
Mentioned: 458 Post(s)
Tagged: 5 Thread(s)
Quoted: 6492 Post(s)
Thanks: 3,232
Thanked 11,022 Times in 8,381 Posts
Mikevernon to the rescue.

https://www.slkworld.com/339719-post137.html


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Jeff, US Army Master Sergeant Retired
Administrator/Founding Member
2009 SLK 55 AMG Black/Black
Kleemann Supercharger thread here:

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Kleemann ECU Tune, headers and downpipes thread here:

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Albums:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

ClearBra
OEM MB Plexiglass Draught Stop
Smarttop version 3.22
Previous - 02 SLK 320, 05 SLK 350
jbanks15 is offline  
#3 Old 10-15-2012
Premium Member
 
Join Date: May 2010
Location: Atlanta
Vehicle: 2005 SLK 55; 2005 SLK 350
Other Toys: Several past R170's
Posts: 4,276
Country:
Chats: 0
Mentioned: 582 Post(s)
Tagged: 0 Thread(s)
Quoted: 901 Post(s)
Thanks: 155
Thanked 514 Times in 475 Posts
How long since the fuel filter was replaced?

And it only happens when below the 1/4 mark?

The fuel has to be pumped a little higher as the tank approaches empty, but at these pressures I doubt the height difference would significantly impact fuel pressure.

If there's a small leak in the plumbing inside the tank above the 1/4 mark, that might account for this -- the leak maintains pressure when submerged, but doesn't when above the surface.

I totally don't get the heat connection -- engine temperature and fuel tank temperature should be unrelated.
efair is offline  
 
#4 Old 10-16-2012
Registered Users
 
Join Date: Jun 2012
Location: Norfolk England
Vehicle: SLK 200 R170
Other Toys: Triumph Tiger 1050, Teal type 35
Posts: 23
Country:
Chats: 0
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 4
Thanked 4 Times in 4 Posts
(Thread Starter)
Hi guys,

Thanks for your replies.
I can see the link to a plumbing leak but would suspect the problem would show under high load and or speed but that is not the case. I did think about the fuel filter, but this was changed less than 6,000 miles ago. The MAF sensor has also been replaced recently as it was cheap and would have been an easy fix.
My thoughts about the tank getting hot is due to the heat coming up from under the car from the exhaust and fuel returning from the engine. (I assume there is some form of relief return to the tank, I am a diesel man )

The power is cut at slow speed and when trying to pull away, I have not had the problem at high speed when the engine is using more fuel than at idle.

I did not suspect the K40 relay as there has never been any problem starting. (as yet!) I can see that if the relay was weak at low volts it could drop out.

I had one occasion where the radio was off so I could hear clearly that the pump was changing note and was quite noisy. I concur that if the electrical supply to the pump was being interrupted this would happen and I have to admit I jumped to the conclusion that the pump was at fault. I did not suspect the relay after reading the K40 threads and thought the fault was more about a starting fault.

Thank you for your thoughts.

Bob
byjingo is offline  
#5 Old 10-16-2012
Premium Member
 
Join Date: May 2010
Location: Atlanta
Vehicle: 2005 SLK 55; 2005 SLK 350
Other Toys: Several past R170's
Posts: 4,276
Country:
Chats: 0
Mentioned: 582 Post(s)
Tagged: 0 Thread(s)
Quoted: 901 Post(s)
Thanks: 155
Thanked 514 Times in 475 Posts
Good point... and for full disclosure I'm just guessing/throwing out ideas here with no practical (or even theoretical) experience. What''s puzzling me most is that it's only when below certain fuel level.

Any other symptoms like backfiring or lignts on the dash?

On my '05 350 the pressure regulator and return are all contained within the fuel tank, there's no return from the engine. Not sure if yours is the same (that should be easy to see with a flashlight).

So what could cause the pump to run at different speeds... 1) different electrical input, or 2) internal binding of the pump, or 3) different back-pressure on the output.

If I was a gambling with your money, I'd start with the pressure regulator and pump.
efair is offline  
#6 Old 11-02-2012
Registered Users
 
Join Date: Jun 2012
Location: Norfolk England
Vehicle: SLK 200 R170
Other Toys: Triumph Tiger 1050, Teal type 35
Posts: 23
Country:
Chats: 0
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 4
Thanked 4 Times in 4 Posts
(Thread Starter)
Thanks Efair, I have had another episode of the cutting out and the engine fault light came on this time with a weak mixture code. I have today replaced the fuel filter and pump. She runs sweet and I hope it stays that way. I did not realize how noisy the pump was.
byjingo is offline  
Sponsored Links
Advertisement
 
Reply

  Lower Navigation
Go Back   Mercedes Benz SLK Forum > Mercedes Benz R170 SLK Class Cars > SLK R170 General Discussion

Bookmarks

Quick Reply
Message:
Options
Upload your files to MEGAUPLOAD
Upload your images to ImageShack

Register Now



In order to be able to post messages on the Mercedes Benz SLK Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
2001 SLK Fuel Pump Problems LIL DON SLK SLK R170 General Discussion 1 08-29-2012 07:04 PM
2001 SLK320 fuel pump GeorgeG SLK R170 General Discussion 11 08-10-2012 02:09 PM
Another IC Pump Install rfourt AMGs 4 05-13-2012 01:00 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome
 

Clubs, Garage Plus vBulletin Plugins by Drive Thru Online, Inc.