No Fuel Pressure '05 CDI - PeachParts Mercedes-Benz Forum

rdlit · #1 01-23-2010, 12:31 PM

Need help with a No Fuel Pressure condition from fuel tank. When the ignition is turned on, It sounds like the electric fuel pump from the tank is running and i hear fuel move through lines or within the tank? Verified no fuel pressure just prior to the Engine Fuel Filter. Any ideas?

Oracle12345 · #2 01-23-2010, 12:41 PM

in the cdi system you have fuel feed pump and a high pressure pump. fuel feed which is mounted in the front supplies fuel to the high pressure pump.

fuel feed pump takes the fuel from the tank through the filter to the high pressure pump via electromagnetic shut off valve.

rdlit · #3 01-24-2010, 09:37 AM

I think I found it. I believe a sticky relay was the culprit, self induced as well due to some adjustments i had made.

Thank you for your help, it got me started on the right track.

Ray...................

pawoSD · #4 01-24-2010, 10:26 AM

Wow that is a complicated setup.

I like my 617 even more now!

Oracle12345 · #5 01-24-2010, 11:08 AM

Quote:

Originally Posted by pawoSD

Wow that is a complicated setup.

I like my 617 even more now!

its not bad just a few more components added to the system

lkchris · #6 01-24-2010, 11:55 AM

Quote:

Originally Posted by pawoSD

Wow that is a complicated setup.

I like my 617 even more now!

Of course the OM648 will leave your car in the dust and get better fuel economy doing it.

Oracle12345 · #7 01-24-2010, 12:14 PM

Quote:

Originally Posted by lkchris

Of course the OM648 will leave your car in the dust and get better fuel economy doing it.

a down side to cdi is the valves arent getting cleaned since the fuel is being shot in the combustion chamber directly but it gets better fuel mileage and goes much better because of the design of the fuel injection combined with the electronic control

pawoSD · #8 01-24-2010, 03:25 PM

Quote:

Originally Posted by lkchris

Of course the OM648 will leave your car in the dust and get better fuel economy doing it.

Not if it is broken down along the way.

Both of them can go 70-75mph on cruise....that's the legal limit, so other than some extra fuel economy, I see no advantages.

samiam44 · #9 01-24-2010, 09:48 PM

Do you understand how a OM617 works? They are IDI engines as the injector pushes the fuel into the pre-chamber. Hence, it doesn't clean the intake valves either.

Ahhh the simplicity versus modern technology!

Oracle12345 · #10 01-25-2010, 10:06 AM

Quote:

Originally Posted by samiam44

Do you understand how a OM617 works? They are IDI engines as the injector pushes the fuel into the pre-chamber. Hence, it doesn't clean the intake valves either.

Ahhh the simplicity versus modern technology!

it doesnt clean the valves directly but some fuel being exposed to the valves

oldsinner111 · #11 01-25-2010, 10:46 AM

Well at least my 617,will start after a EMP explosion.Real Diesels don't need sensors,computers,or crappy aluminum blocks.Let's see a CDI go 800,000 miles. Oh yeah I've already blown several E Class diesels up mountains.Their so smogged down,they choke.

Eric · #12 01-25-2010, 11:51 AM

Quote:

Originally Posted by oldsinner111

Well at least my 617,will start after a EMP explosion.

except youll be fried if youre close enough to the explosion to be affected by the EMP. if you're not close enough but your car is, the car will be heavily irradiated (if its still there).

portable emp machines powerful enough to kill a car computer won't exist. the energy needed to make a directed emp powerful enough takes a small substation or an atom bomb. Unless somebody is going around with a 3 ton machine and killing individual cars, you've got nothing to worry about.

oldsinner111 · #13 01-25-2010, 01:13 PM

I'm talking about WW3,when a nuke is exploded a 100 miles up,wiping out North Americas electronics.

andrewjtx · #14 01-25-2010, 01:39 PM

For those that aren't aware. You don't want to mess with the fuel return before it get's cooled. Hence the fuel cooler in line before the tank.

The heat generated from the high-pressure pumps is crazy. I did a diesel purge on the wifes' VW PD TDI... wow.

Alastair · #15 01-25-2010, 04:15 PM

Quote:

Originally Posted by andrewjtx

For those that aren't aware. You don't want to mess with the fuel return before it get's cooled. Hence the fuel cooler in line before the tank.

The heat generated from the high-pressure pumps is crazy. I did a diesel purge on the wifes' VW PD TDI... wow.

Hmm....

The comparison of the VW TDi 'PD' system and the Mercedes-Benz CDI is like comparing an OM.617 Bosch M/MW fuel-system to a CDI fuel-system....

---They are Completely Different!

--P.D System = Unitised High Pressure Injectors combined with the injection pump individually driven off separate lobe on Cam-Shaft--The Pump is a plunger type driven from cam immediately above the injector nozzle and the Injector opening/closing/Pilot-Injection etc, controlled by electronic means from the ECU....

CDI, as M.B. call that system on its vehicles, (or more properly called, Common-Rail) = High Pressure Rail-Pump, supplying an 'Accumulator Rail' with individual supply pipes to each injector. All injectors 'see' the same pressure as contained in the accumulator rail from the H.P. Pump at all times. The actual Pressure is altered by the Rail Regulator according to speed and load.

The Injectors are opened electronically by the ECU by solenoid valves or piezo-crystals--the latter on Gen II/III C.R. diesels found here in Europe C.R. Systems are now VERY Common here.....

The VW TDi-- 'Pumpe Duse' system is a higher-pressure system, and as such can heat the fuel significantly--Especially as the fuel galleries pass Through the Cylinder-Head metal!

The CDi has a fuel Cooler merely as a Precaution for those vehicles fitted with Plastic Fuel-Tanks, ( A Class and some C Class...) and exported to warmer climates, (Source, M.B. CDi Training DVD)