Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help




Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Mercedes-Benz SL Discussion Forum

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 07-02-2018, 11:35 AM
Registered User
 
Join Date: May 2011
Location: Omaha, NE
Posts: 23
Is it time for a new fuel pump?

I bought a 1988 560SL in 2011 with 134k miles that now has 147k miles. It was well-maintained, but I just replaced the factory fuel filter last year - my Mercedes-only mechanic said it still had some of the "goo" spray on it from when it was shipped from Germany. Regardless, while it always starts right up, even after storing it for 6 months, it occasionally would not start if I tried to start it again shortly after shutting it down at operating temperature. I just thought I was flooding it and would wait a while, then try again and it always started again. However, after about a 125-mile drive yesterday, which included two stops, I got home and shut it off in the driveway, then went back to move it and it wouldn't start. Turns over fine and fires just a little bit at the initial turn-over, but won't keep running. When I took off the air cleaner to vent it, that didn't help, but I found it would fire if I splashed a little fuel in the intake, but only until the fuel was gone. I know I need fuel and spark, and that I have the spark if I manually add a little fuel, but is there a good way to confirm the fuel pump is the problem, versus an electrical problem not powering the pump?
Reply With Quote
  #2  
Old 07-02-2018, 11:40 AM
Diseasel300's Avatar
Registered User
 
Join Date: May 2016
Location: Texas Hill Country
Posts: 4,666
The fuel pump RELAY is a very common source of woe on the later 107's and other models that use the same fuel injection system. The relay is actually a printed circuit board and they're known for lousy solder joints and burned traces caused by hot connections. I'd start there. Another common source of problems with hot-starting is the fuel accumulator, however if the fuel pumps are working, the car will splutter to life after an extended crank.
__________________
'11 Honda Accord EX - "The Daily" 64K
'83 500SL Euro - "The Money Pit" 116K
'91 350SD - "The Diseasel Jr." 168K
'86 300SDL - "The Diseasel" 189K (Totaled 1/31/19)
The Diseasel Thread - Everything You Didn't Know You Wanted To Know
Reply With Quote
  #3  
Old 07-02-2018, 11:43 AM
Registered User
 
Join Date: May 2011
Location: Omaha, NE
Posts: 23
Thanks for the quick response! I see fuel pump relays are listed in the Parts Catalog and would rather try replacing this first, so is this relay also located behind the glove box? (I remember having to replace some other relay that required removing the glove box). Thanks!
Reply With Quote
  #4  
Old 07-02-2018, 12:21 PM
Diseasel300's Avatar
Registered User
 
Join Date: May 2016
Location: Texas Hill Country
Posts: 4,666
Not sure where it's located on the Gen II 107's. My '83 just has an ice cube relay in the kickwell so not much use as a reference. I'd imagine if you did a Google search, someone either on this forum or over on BW has done a writeup with pictures. Fuel pump relays are a pretty common source of woe on the CIS-E cars.
__________________
'11 Honda Accord EX - "The Daily" 64K
'83 500SL Euro - "The Money Pit" 116K
'91 350SD - "The Diseasel Jr." 168K
'86 300SDL - "The Diseasel" 189K (Totaled 1/31/19)
The Diseasel Thread - Everything You Didn't Know You Wanted To Know
Reply With Quote
  #5  
Old 07-03-2018, 10:17 AM
rowdie's Avatar
Registered User
 
Join Date: Nov 2008
Location: NE Oklahoma
Posts: 1,408
Fuel pump relay is behind the glove box. Do you hear the pumps for a few seconds when ignition is first turned on? Does it start cold?

Your symptoms point to the accumulator. If is located above the fuel filter. It maintains pressure in the system for a time to assisted in warm starts. When it fails the pressure bleeds off making it hard to start.
Reply With Quote
  #6  
Old 07-06-2018, 10:10 AM
Registered User
 
Join Date: May 2011
Location: Omaha, NE
Posts: 23
Thanks for everyone's input! While I had replaced the original fuel pump relay within the last 5,000 miles (or one that had been replaced with a genuine Mercedes part), I went ahead and ordered another URO relay from the parts catalog and it arrived yesterday. Before replacing it, I tried to start the car once more, but it just turned over and wouldn't fire. So, I replaced the fuel pump relay and when I turned the key, it fired up right away and I took it for a drive around the neighborhood. While I am disappointed my URO replacement part only lasted about 5,000 miles, at least it is a lot less expensive than a fuel pump and much easier to change. I still have the original Mercedes part in my glove box, which I will keep there in case the URO part goes bad again, since the Mercedes part would work occasionally and the URO part that I just replaced would not. Thanks!
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not 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 On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 12:27 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page