1995 E300 W124-Om606 pressure in fuel tank
 

I posted here a couple of months ago about a problem I was having with pressure building in the fuel tank. I have not done anything yet to correct the problem. If I fill the tank with fuel and drive the car for several miles the engine will die when I get to a stop sign but it will restart. If I loosen the fuel cap and relive the pressure the engine will stay running, so I leave the fuel cap loose and all is well. I now see fuel leaking from somewhere on or around the IP. Some of you guys have suggested I replace "O" rings on the pre filter or replace the lift pump so I decided it was time to educate myself on some of this stuff!
I think I found out where the pre filter is, the tiny one located on top of the large canister one? And the lift pump is located on the side of the IP?
With the engine running I noticed the fuel line from the lift pump to the fuel filter has bubbles flowing thru it.Would this suggest that the lift pump is failing?
I have also noticed a high pitch squealing noise that seems to be coming from around or near the lift pump but the noise is very difficult to pin point, It sounds very similar to a dry rotating bearing that is crying for oil.
Thanks for your help.

If you have bubbles in the supply line from the lift pump, you know where your pressure is coming from. You could have a failing lift pump, or more likely you have a rotten bit of fuel line or a poor seal somewhere. Follow the suction side tubing and renew any rubber parts you find.

As for the squealing - could be worth your time to inspect the vacuum pump, especially if there's no history of it being replaced.

Check the tank vent, sometimes located in nr side (UK) wing (fender).

I think I will start by replacing all the "O" rings at the ends of the fuel lines.
The clear tubing seems to be very stiff or maybe even brittle and I can imagine it breaking as I attempt to replace the "O" rings.
Before I attempt this I would like to have some fuel line tubing on hand, can it be purchased in a long length that can be cut to length as needed or does it need to be purchased as a part (pre-cut and shaped) that is specific to this car?

The low pressure fuel lines can be purchased as new parts. The whole group will be around $100. Be sure to get the crush washers for the return line from the IP, this is still an old school banjo bolt connection.

The trick for the connectors:
The horseshoe needs to be free floating in the center of its travel for the connector to be locked. To unlock the connector, push the back of the horseshoe (imagine the part you would grip if you were to toss a full size one) towards the center. This pushes two internal tabs which release the connector from the port.

Packerfan you need to update your profile .To get more help. As members need to know just what car you need information for or help with.

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well...post title itself is good starting point :)

cheers

And just to help out our international friends, a little background on the US models.

The 1995 E300 in the US is a W124 model. Engine is an OM606.910 naturally aspirated.

Starting in 1996 the E300 was introduced as the W210 version, we had 1996 and 1997 with the OM606.912 (essentially the same engine, except has the drive by wire injection pump, still naturally aspirated), and then 1998 and 1999 with the OM606.962 turbo version.

Then no more diesel in the US until 2005-2006 with the W211 E320 CDI.

All of these were sedans, no diesel wagons (last year was 1987!) available.

Thank you for the detailed procedure on unlocking the horseshoe connectors, I would have tried to pull on them rather than push!
I am ready to order the low pressure fuel lines and when I look under the the hood I see 3 of them, is that correct?
Thanks again for your help.
Rick

I'm not sure what additional info. you are asking for. The car is a 1995 E300

Rick, check again, you should see more than three. Three come off the back of the fuel filter ( I am having a time finding the center one) and one more up to the pre-filter. And I bet I am missing one maybe, sitting at my desk. So four or more+.

I had basically the same problem. New lift pump solved it. You might as well do the fuel line O rings. They need to be renewed every few years anyway.

Rgds,
Chris W.
ex '95 E300D, 467K

Thanks Chris, I will replace all low pressure fuel lines and O rings and see if the bubbles disappear. If they are still there I will replace the lift pump as you suggest. The engine has 398000 miles on it and I have not renewed anything but delivery valve O rings.

Thanks again for your help,
Rick

Thank you Spock505,
The detailed diagram you provided is just what I needed.
This is what I love about this forum, so many helpful people like you here willing to take the time to help others.

Thanks again,
Rick
Go Pack Go!