83 300SD Fuel Pump Down? - Mercedes-Benz Forum
 
LinkBack Thread Tools Display Modes
#1 (permalink) Old 07-14-2007, 06:48 PM
BenzWorld Junior Member
 
Date registered: Sep 2005
Posts: 17
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
Unhappy 83 300SD Fuel Pump Down?

Couldnt get my car started..along the way I did this:

disconnected the "out" hose from the pump and was able to squirt out diesel fuel
using the prime button till the cows came home. When I crank the car over, nothing comes out of the hose. Im thinking the pump is toast yes? Should add that I have a new fuel filter on...

Last edited by Tom Yaz; 07-14-2007 at 06:50 PM.
Tom Yaz is offline  
Sponsored Links
Advertisement
 
#2 (permalink) Old 07-14-2007, 06:59 PM
BenzWorld Elite
 
jdc1244's Avatar
 
Date registered: Jun 2003
Vehicle: 1991 300 SE
Location: Lakeland, Florida
Posts: 18,534
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Not necessarily – I’d make sure the fuel system is not leaking fuel or air. Then check the fuel tank strainer is not clogged. How many miles on your car? Recent work?
jdc1244 is offline  
#3 (permalink) Old 07-14-2007, 07:14 PM
BenzWorld Junior Member
 
Date registered: Sep 2005
Posts: 17
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
No recent work...268K miles. Fuel tank strainer? Your talking about that small inline filter under the hood? That has been replaced as well. On the air leak possibility, wouldnt I have problem hand pumping if there was an air leak?
Tom Yaz is offline  
#4 (permalink) Old 07-14-2007, 07:19 PM
BenzWorld Elite
 
jhodg5ck's Avatar
 
Date registered: Sep 2002
Vehicle: Depends on the day!
Location: Atlanta, GA (Lilburn)
Posts: 13,272
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Send a message via AIM to jhodg5ck
No, there is a fuel screen in the tank itself...likes to clog esp. on higher mileage cars.

Jonathan

Blue Ridge Mercedes/AMG East
Jonathan Hodgman
http://www.blueridgemb.com/
Enthusiast Service, Restoration & Tuning.
Authorized RENNtech Dealer & Installer
Follow Us on Facebook!
Located in the Atlanta area

87 Hammer Wagon 6.0L 32V
87 Hammer 6.0L 32V
86 560SEL AMG 6.0 32V
etc....

Mercedes Repair Atlanta
jhodg5ck is offline  
#5 (permalink) Old 07-14-2007, 07:34 PM
BenzWorld Junior Member
 
Date registered: Sep 2005
Posts: 17
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
Thats a new one for me...didnt know there was one..If I cant get it resolved under the hood, I will have to get my mencanic to look at that..If I had a air leak or the tank filter you mention is clogged, how can I pump sucessfully by hand but not by cranking? Shouldn't I have problems hand pumping as well?
Tom Yaz is offline  
#6 (permalink) Old 07-14-2007, 07:45 PM
BenzWorld Elite
 
Date registered: Feb 2007
Vehicle: 300SD
Location: Florida, USA
Posts: 11,134
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 40 Post(s)
When cranking the engine, the diesel injection pump cylinders pump the fuel into the injection lines/injectors at about 2,000 psi. When you use a hand pump, you are only pressurizing the fuel to several psi to purge the air out of the system. Be glad that nothing comes out of that disconnected hose when cranking the engine.

Loosen the bolt on top of the main fuel filter. Then hand pump the fuel until you see it coming out of the filer housing under the loosened bolt. Tighten the bolt and try cranking the engine.
p100 is offline  
#7 (permalink) Old 07-14-2007, 08:20 PM
BenzWorld Junior Member
 
Date registered: Sep 2005
Posts: 17
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
Hi P100, you got me a bit confused now..What I am "hand pumping" is the primer button on the lift pump. If the lift pump is not supposed to be "lifting" fuel out its exit hose to the fuel filter when cranking,("be glad nothing is coming out") then what is it good for?

When I said "fuel pump" I mean the lift pump, not the injection pump....

Or am I misunderstanding something?

Last edited by Tom Yaz; 07-14-2007 at 08:23 PM.
Tom Yaz is offline  
#8 (permalink) Old 07-15-2007, 07:07 AM
BenzWorld Newbie
 
Date registered: Jul 2007
Vehicle: 1982 300sd, 1981 Harley davidson FLT
Location: Indiana
Posts: 2
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
The fuel supply pump only runs at a few psi. The injector pump delivery pressure is the high pressure side.
The tank screen is a prefilter to keep the big cunks out of the fuel lines. ie: rust and debris in the tank. You would think that if the tank screen was plugged or had a cracked fuel supply line that the primer pump wouldn't draw fuel either. Where is the supply pump located on your car? Under hood or in the tank? It makes a difference if the pump sucks or pushes the fuel through the line. A leak on the suction side will draw air, cause the pump to cavitate and only leave some reisdue at the spot of the leak when the pump is not running. A leak on the preasure side will leave you with a big puddle. Also a leak on the suction side makes it difficult for the pump to prime itself.
Also have you checked the fuel pump relay? It should be loacated under the hood with the fuse panel. When the canister filter was changed during priming the system did you open the bleeder screw on the injector pump? injector pumps do not like air in any amount.
isc62 is offline  
#9 (permalink) Old 07-15-2007, 07:28 AM
BenzWorld Extremist
 
zviratko's Avatar
 
Date registered: Jan 2007
Vehicle: W124 400E, W126 500SE
Location: Prague
Posts: 968
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
There is no external fuel pump on OM617 (I think), the fuel pump is in directly connected to the engine. You are disconnecting the line leading "to" the pump, so that's the reason nothing is coming out. But it should suck air
zviratko is offline  
#10 (permalink) Old 07-15-2007, 07:31 AM
BenzWorld Junior Member
 
Date registered: Sep 2005
Posts: 17
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
Quote:
Originally Posted by isc62
The fuel supply pump only runs at a few psi. The injector pump delivery pressure is the high pressure side.
The tank screen is a prefilter to keep the big cunks out of the fuel lines. ie: rust and debris in the tank. You would think that if the tank screen was plugged or had a cracked fuel supply line that the primer pump wouldn't draw fuel either. Where is the supply pump located on your car? Under hood or in the tank? It makes a difference if the pump sucks or pushes the fuel through the line. A leak on the suction side will draw air, cause the pump to cavitate and only leave some reisdue at the spot of the leak when the pump is not running. A leak on the preasure side will leave you with a big puddle. Also a leak on the suction side makes it difficult for the pump to prime itself.
Also have you checked the fuel pump relay? It should be loacated under the hood with the fuse panel. When the canister filter was changed during priming the system did you open the bleeder screw on the injector pump? injector pumps do not like air in any amount.

Yes we are talking about the fuel supply pump. It is located under the hood. It is mechanical and doesnt use electricity. Yes I agree that if I can manually prime (suck) just fine then it would follow it should also lift mechanically. Hence the issue. I have disconnected the outlet line so that the injection pump is out of the equation. I am priming into a can right now. I can fill up the can with hand priming, but cant do it mecahnically (cranking). So I am thinking the lift pump is malfunctioning
Tom Yaz is offline  
Sponsored Links
Advertisement
 
Reply

  Mercedes-Benz Forum > Mercedes-Benz Sedan Forums > W126 S,SE,SEC,SEL,SD,SDL Class

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Mercedes-Benz 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:
If you do not want to register, fill this field only and the name will be used as user name for your post.
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:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




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
Display Modes
Linear Mode Linear Mode



Similar Threads
Topic Author Forum Replies Last Post
Changed my fuel pump to fix my fuel gauge, and got an added BONUS. mikewired W163 M-Class 15 03-04-2012 09:52 AM
fuel air mix / testing fuel pumps and pump pressure william.wood W126 S,SE,SEC,SEL,SD,SDL Class 0 11-09-2005 12:32 PM
380sel where is the fuel pump fuse? have no power to pump meggala W126 S,SE,SEC,SEL,SD,SDL Class 3 08-02-2005 04:44 AM
leaking hand pump vs fuel pump benzmeover W123 E,CE,D,CD,TD,TE Class 4 01-30-2005 08:36 PM
Update on Fuel Gauge Problem: Got Fuel Pump Replaced Today tjhsiao W163 M-Class 4 10-25-2002 05:47 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

 

Title goes here

close
video goes here
description goes here. Read Full Story
For the best viewing experience please update your browser to Google Chrome