Replaced K40/fuel lines still no pumping - PeachParts Mercedes-Benz Forum

Tasma · #1 03-22-2011, 11:19 AM

I have replaced the K40 relay and all fuel lines and o-rings on my 1999 E300 turbo and it still will not pump fuel up to the injectors. I hear the shut off valve click when the key is turned but no fuel ever comes out of the delivery valves ( I can see because I haven't re connected the injector lines.)

Can the shut off valve click and still be bad? What else in the system could stop the pump?
When the car stopped working it completely died. It never fired a bit when I tried to start it. It had been running OK but I had the problem of it dying after starting so I did the normal parts replacement as suggested.

Jadavis · #2 03-22-2011, 11:53 AM

Basic question: if you disconnect the return fuel line and put it in a jar, then crank do you get fuel in the jar? (there is an official spec for a 30 second crank, I don't know it.) This will test the fuel system through the lift pump.

Jim
(You probably already checked this, but I thought I would make sure.)

TMAllison · #3 03-22-2011, 02:04 PM

1) Is there air in any of the fuel lines?

2) Have you double checked the way the lines are routed? You wouldn't be the first person to get the lines from the lift pump to the cannister filter and back to the SOV on backwards.

3) Tried disconnecting the line from the lift pump and cranking to see if fuel is making it past that point up to the cannister filter and back down to the SOV?

Tasma · #4 03-22-2011, 03:07 PM

There is fuel in both lines going down to the SOV.
The only line that doesn't show fuel is the one from the engine block side of the injector pump going back up to the return fuel junction.

I followed the diagram found on this site. The center line from the fuel filter assembly goes to the front of the SOV and the line coming from the back side of filter assembly goes to the back side of SOV.

The strange thing is, when I stop cranking the fuel flows backward from the pre filter toward the fuel heater so it looks as if there is no fuel. But as soon as I crank again the line fills with fuel. This does not happen if I jack up the back of the car. The tank is full.

I replaced the pre filter and o rings.
I can't find the link that shows the fuel diagram again so if anyone knows where it is please post it.
I have seen some references to SOVs going bad. Is there a way to check them? It makes a clicking sound when the key is turned but does that prove that it's OK?

How long do you need do you normally need to crank to get the system primed?
I filled the filter before putting it on with new o rings on the bolt that attaches the filter.

TMAllison · #5 03-22-2011, 08:31 PM

So, the line comming from the bottom of the prefilter down to the sov has no fuel?

Did you replace the $.25 (as in as big as a quarter) sized oring on the underside of the prefilter? Sure that its installed?

Tasma · #6 03-22-2011, 09:14 PM

Both lines to the shut off valve have fuel in them. I did replace the o ring under the pre filter.
The line that doesn't have fuel in it is the one from the engine block side of the injector pump (attached with 17mm bolt) that goes up to the tee that is the return line junction on the passenger side of the filter assembly.

TMAllison · #7 03-23-2011, 11:26 AM

http://bp3.blogger.com/_p71v9ofBM6w/R5ZR4hrNUFI/AAAAAAAAAIQ/XCBQ40qtPDQ/s1600-h/fuelflow.JPG

I believe you are talking about line #6 in the diagram? It is a return line with a check valve at the IP (17mm part). Dumps into line 8 along with 7 (return from inj's) back to the tank.

Check the path (especially 2-5) and make certain everything is in the right place. If it is, pull the top of 4 or the bottom of 5, and see if fuel comes out when cranking. If it doesnt, the lift pump may be bad (can be rebuilt). If it does, it could be a leaky SOV oring or bad SOV.

Tasma · #8 03-23-2011, 12:52 PM

Fuel comes out of those lines when cranking. I have also raised the back of the car so that gravity causes fuel to run into the system. It is starting to seem like the SOV valve might be bad but I don't want to spend money on a new one if there is a way to test the one on the car.

Does the valve clicking indicate that it's working, or could it still be a failure. It clicks when my wife turns the key on.

TMAllison · #9 03-23-2011, 01:11 PM

The click would make it seem that it is openning. I guess the question then is does the SOV open fully or not. They can get "sticky". Sometimes that is caused by a bad oring so is probably worth checking that it isnt seated incorrectly or nicked.

You ought to be able to release a couple of fuel lines up top and at the lift pump and pull it out of the IP with the IM still installed. Move the windsheild washer bottle for some working room. Don't know if its possible to see the moving parts inside the SOV or not. Never tried. Could try using a mirror and light while the key is cycled.....

Tasma · #10 03-27-2011, 08:23 AM

I left the car sitting all night with the back wheels jacked up. The next morning after cranking about 30 seconds it fired up. I guess this car is just hard to prime.
I drove it down the driveway and almost didn't make it back to the garage. The transmission was slipping like crazy. Error code 715 shows up on the OBD.

Ordered a new conductor plate for the transmission. I am almost getting to the point of being afraid to drive this car somewhere.