SL/R129: Fuel Leak/Pump Issue
#1
Junior Member
Thread Starter
Fuel Leak/Pump Issue
hi. i have a fuel leak and the following symptoms: car starts normally cold but fuel pump stays on 3 minutes. Vacuum line into pressure regulator is dry insude. after a short drive, harder to start, smell of raw fuel in the cabin,vacuum line into pressure regulator is now wet inside.
I did a fuel pressre test, which yielded the following: With engine cold and key in the 2nd position, fuel pressure is 10 psi. When engine is s started, fuell pressure stays steady at 48 psi; when turned off, pressure falls immediately to 30 psi, then decreases to zero over 15 mins. When the pressure regulator vacuum line is disconnected while the engine is running, pressure jumps to 58 psi.
I intend to replace the fuel filter, some of the fuel lines, the pressure regulator, and the injector o-rings. Do I need to replace the fuel pump and/or flush the tank?
Havng a hard time locating the pump and filter under the car.
The car has 129K, has been neglected, and has no service record prior to my ownership.
Thanks in advance.
I did a fuel pressre test, which yielded the following: With engine cold and key in the 2nd position, fuel pressure is 10 psi. When engine is s started, fuell pressure stays steady at 48 psi; when turned off, pressure falls immediately to 30 psi, then decreases to zero over 15 mins. When the pressure regulator vacuum line is disconnected while the engine is running, pressure jumps to 58 psi.
I intend to replace the fuel filter, some of the fuel lines, the pressure regulator, and the injector o-rings. Do I need to replace the fuel pump and/or flush the tank?
Havng a hard time locating the pump and filter under the car.
The car has 129K, has been neglected, and has no service record prior to my ownership.
Thanks in advance.
#3
Junior Member
Thread Starter
i ordered the parts and more importantly found the fuel pump and filter. The rubber lines are all crumbly and disintegrated. How do you remove the pressure regulator? Thank you
#5
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These sites could help:-
http://www.benzworld.org/forums/w140...gulator-r.html
https://www.pelicanparts.com/techart...eplacement.htm
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http://www.benzworld.org/forums/w140...gulator-r.html
https://www.pelicanparts.com/techart...eplacement.htm
-;ZAYED;-
#7
Junior Member
Thread Starter
Fuel Pump Relay
I replaced the injector seals and fuel pressure regulator yesterday and plan to replace the fuel filter today. I have been told to relieve the fuel pressure prior to removing the fuel filter by removing the fuel pump fuse. Where is the fuse? My fusebox card doesn't mention one. Would disconnecting the fuel pump relay accomplish the same thing?
My fuel pump and filter are behind a shield. How hard is it to remove the shield?
My fuel pump and filter are behind a shield. How hard is it to remove the shield?
Last edited by wahnsinn; 07-21-2018 at 03:06 PM. Reason: press send before finishing
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#9
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Thread Starter
Fuel Pump Fuse
The Pelican Parts how-to guides for replacing the injectors and the fuel filter start with removing the fuse for the fuel pump and cranking the engine until it stalls in order to relieve the fuel pressure. There is no fuse in my fusebox labeled fuel pump. There is a fuel pump relay in the trunk. I replaced the O-rings on the injectors and the filter without removing any fuses.
In re the fuel filter: the arrow points in the direction of the fuel flow, right? as far as i can tell, the fuel flows from the tank to the pump then to the filter then forwards to the engine. The way the pump and filter are configured, the arrow ends up pointing to the rear of the car.
In re the fuel filter: the arrow points in the direction of the fuel flow, right? as far as i can tell, the fuel flows from the tank to the pump then to the filter then forwards to the engine. The way the pump and filter are configured, the arrow ends up pointing to the rear of the car.
#10
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No need to remove fuel pump relay to replace FPR or even pump/filter..!,,
it's not that hard to replace the fuel pump or filter either:-
they located under the car (rear passenger side),,
just need to remove the dust shield, will see them together..!!
*fuel pump/filter location:-
*FPR replacement:-
-;ZAYED;-
it's not that hard to replace the fuel pump or filter either:-
they located under the car (rear passenger side),,
just need to remove the dust shield, will see them together..!!
*fuel pump/filter location:-
*FPR replacement:-
-;ZAYED;-
#11
Junior Member
Thread Starter
update
thanks for that. as i said, i have already located and replaced the filter. i asked about the fuse and relay because multiple sources suggested relieving the fuel pressure prior to working on the system by cranking the engine with the fuel pump fuse removed but I couldn't find said fuse.
I still have a fuel leak which is probably caused by cracking hoses connected to the pump and filter. Too hot here all week to do anything outside here so I won't resolve the issue for a while.
I still have a fuel leak which is probably caused by cracking hoses connected to the pump and filter. Too hot here all week to do anything outside here so I won't resolve the issue for a while.
#12
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Thread Starter
Fuel Hose
I bought this fuel hose, which was described as "from fuel line to fuel pump." It resembles nothing I have connected to my fuel pump but appears to be identical with the one of the two hoses in the engine compartment connected to the fuel rail. Can anyone verify its placement on the vehicle?
Should all fuel lines be braided??
after market fuel line
Should all fuel lines be braided??
after market fuel line
#13
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As i remember; 96-98 Sl500 fuel rail got two hoses:-
*Fuel rail to Engine #: "129 470 22 75", Braided hose.
*Fuel cooler to fuel rail #: "129 470 24 75", Rubber hose.
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*Fuel rail to Engine #: "129 470 22 75", Braided hose.
*Fuel cooler to fuel rail #: "129 470 24 75", Rubber hose.
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