Mercedes-Benz Forum banner

1 - 11 of 11 Posts

·
Registered
Mercedes w210 E230 1996 sedan (210.037) (Engine: M111.970) (transmission:722.440)
Joined
·
10 Posts
Discussion Starter #1 (Edited)
my w210 suffering from ocasional fuel pressure loss, i shut off my car and come back half hour later and 70% of the time the pressure is still there, but sometimes the fuel pressure is completely gone or close. so then i turn key on and off till i hear the fuel pump (load up/slow down) and the car starts and runs smoothly.
im thinking it could be a injector but don't know how i would do a injector test

so now i dont know what to do any tips is greatly appreciated

-fuel pump and filter have been changed a year ago, bought cheap pump & filter so wouldn't rule it out

- the fuel pump starts every time i turn the key

- I've changed fuel pressure regulator on the fuel rail with a new bosch one (no change)

- the car: W210 e230 1996 m111.970 engine
 

·
Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
Joined
·
3,405 Posts
Most mercedes fuel pump have a one way check valve that usually maintains pressure in the fuel rail for the fastest start up. Sounds like your (cheap) fuel pump may not have the check valve installed... look into adding a check valve inline after the fuel pump.
 

·
Registered
Dallas, Texas
Joined
·
6,990 Posts
my w210 suffering from ocasional fuel pressure loss, i shut off my car and come back half hour later and 70% of the time the pressure is still there, but sometimes the fuel pressure is completely gone or close. so then i turn key on and off till i hear the fuel pump (load up/slow down) and the car starts and runs smoothly.
im thinking it could be a injector but don't know how i would do a injector test

so now i dont know what to do any tips is greatly appreciated

-fuel pump and filter have been changed a year ago, bought cheap pump & filter so wouldn't rule it out

- the fuel pump starts every time i turn the key

- I've changed fuel pressure regulator on the fuel rail with a new bosch one (no change)

- the car: W210 e230 1996 m111.970 engine
Interesting. So, what is affected? Cold or warm start-ability?

Or, just simple case of OCD?
 

·
Registered
Mercedes w210 E230 1996 sedan (210.037) (Engine: M111.970) (transmission:722.440)
Joined
·
10 Posts
Discussion Starter #5
it doesn't affect starting at all if i let the fuel pressure build up before starting
if i don't it will run rough 3sec until the pressure gets buildt up



my w210 suffering from ocasional fuel pressure loss, i shut off my car and come back half hour later and 70% of the time the pressure is still there, but sometimes the fuel pressure is completely gone or close. so then i turn key on and off till i hear the fuel pump (load up/slow down) and the car starts and runs smoothly.
im thinking it could be a injector but don't know how i would do a injector test


any tips on what the problem could be, is greatly appreciated


  • fuel pump and filter have been changed a year ago, bought cheap pump & filter so wouldn't rule it out
  • the fuel pump starts every time i turn the key
- I've changed fuel pressure regulator on the fuel rail with a new bosch one (no change)

- W210 e230 1996 m111.970 engine
Interesting. So, what is affected? Cold or warm start-ability?

Or, just simple case of OCD?
 

·
Registered
Mercedes w210 E230 1996 sedan (210.037) (Engine: M111.970) (transmission:722.440)
Joined
·
10 Posts
Discussion Starter #6 (Edited)
im pretty sure i saw the one way valve screwed on the end of the fuel pump when installing it.
the fuel pressure in the rail is mostly there, but the pressure occasionally bleeds off when i shut off the engine , when it doesn't bleed off the car can sit 4days and start right away


Most mercedes fuel pump have a one way check valve that usually maintains pressure in the fuel rail for the fastest start up. Sounds like your (cheap) fuel pump may not have the check valve installed... look into adding a check valve inline after the fuel pump.
Most mercedes fuel pump have a one way check valve that usually maintains pressure in the fuel rail for the fastest start up. Sounds like your (cheap) fuel pump may not have the check valve installed... look into adding a check valve inline after the fuel pump.
 

·
Registered
Mercedes w210 E230 1996 sedan (210.037) (Engine: M111.970) (transmission:722.440)
Joined
·
10 Posts
Discussion Starter #7
ok ill try to do the test in the near future, and will my car get any fault codes when i disconnect the injectors and turn on the ignition?


Hello :).

Here is the way you test the fuel pressure for your car.

1 bar = 14.5 psi.

https://manual.startekinfo.com/manual/JSP/e4/9_2/m32.jsp

To test the fuel injectors you remove the fuel rail and the injectors, and check for leaking injectors with the ignition ON.

https://manual.startekinfo.com/manual/JSP/e4/9_2/m36.jsp
Most mercedes fuel pump have a one way check valve that usually maintains pressure in the fuel rail for the fastest start up. Sounds like your (cheap) fuel pump may not have the check valve installed... look into adding a check valve inline after the fuel pump.
Hello :).

Here is the way you test the fuel pressure for your car.

1 bar = 14.5 psi.

https://manual.startekinfo.com/manual/JSP/e4/9_2/m32.jsp

To test the fuel injectors you remove the fuel rail and the injectors, and check for leaking injectors with the ignition ON.

https://manual.startekinfo.com/manual/JSP/e4/9_2/m36.jsp
 

·
Premium Member
1998 E320 base sedan @ 160kmiles
Joined
·
6,015 Posts
ok ill try to do the test in the near future, and will my car get any fault codes when i disconnect the injectors and turn on the ignition?
No. You remove the injectors and turn the ignition ON without starting the engine. The fuel line will have the fuel pressure, if any of the injectors leak, you will see. If you have intermittent issue with the fuel pressure, your fuel pump check valve is already there but somewhat either it is opening or some other relief valve for return is opening, maybe for protection.
 

·
Registered
Mercedes w210 E230 1996 sedan (210.037) (Engine: M111.970) (transmission:722.440)
Joined
·
10 Posts
Discussion Starter #9
sorry i didn't explain well enough, by turning Ignition ON i meant to turn it on so that the fuel pump starts, not cranking the engine. :)

but in the manual you sent it says to do a leak test and a spray test where i need to create and connect up a self-made harness,
and just like the car can detect when a bulb is burnt or not connected, can the car detect when there is no injector connected?









No. You remove the injectors and turn the ignition ON without starting the engine. The fuel line will have the fuel pressure, if any of the injectors leak, you will see. If you have intermittent issue with the fuel pressure, your fuel pump check valve is already there but somewhat either it is opening or some other relief valve for return is opening, maybe for protection.
 

·
Premium Member
1998 E320 base sedan @ 160kmiles
Joined
·
6,015 Posts
You asked about the fuel injector leak test. The spray test is not relevant for loss of fuel pressure you are investigating.

The Engine computer recognizes fuel injector electrical issues as it monitors the current through the actuator. If detected, it will generate P020X faults when injector voltage and amperes are beyond threshold level.. The fault is cleared when the fault condition is cleared.
 
1 - 11 of 11 Posts
Top