Time for my diesel shower... perhaps? - PeachParts Mercedes-Benz Forum

TylerH860 · #1 10-23-2008, 11:00 PM

I've been noticing a power loss as my tank gets below 1/3. Since both fuel filters are new, the next logical course of action is to clean the tank strainer/sender.

Tonight it was getting very bad, taking around 30 seconds to get up to 40 and barely maintaining that speed. The fuel is down to a trickle coming into the primary filter (should be full at all times correct?); I'm surprised its running at all. I tried switching the return and incoming line, but it offered no improvement. I'm not sure whether I should dismiss this because the tank is low, or go after the sender first. Opinions? I'm intentionally allowing the fuel to run low so I can easily drain the tank if needed.

Where do I get to the sender, btw?

Chad300tdt · #2 10-23-2008, 11:16 PM

Hey Tyler,

I'm assuming this is on Norm right?

The sender can be accessed from inside the car in the hatch area. I used two channel locks to unscrew it. One to bite the sender and the other to grab the first and turn it out. The sender is kind of sunken down and one pair of channel locks couldn't get a clean bite and have the proper leverage to turn it out.

Also, take Kerry's tip about draining the tank. Disconnect the fuel return line under the hood and run it onto a fuel can. Then let the car run until it stalls out. Your tank will be empty and the fuel will be filtered and ready to pour back in when you're done cleaning the strainer.

TylerH860 · #3 10-23-2008, 11:16 PM

In addition, there is no whooshing noise when I loosen the fuel cap.

Nope.... Its on good Ol' Turbo....

daw_two · #4 10-23-2008, 11:21 PM

Tyler....which car?

The fuel sender is UNDER the first aid kit compartment in a a 300D sedan; remove 2 screws and then remove the first aid kit compartment.

The fuel sender for your wagon is under the black tray that is in the back of the hatch area.

Have you tried loosing your fuel filler cap? Maybe it has a vacuum on it.

Chad300tdt · #5 10-23-2008, 11:21 PM

Oh well, you can still do the tank draining trick.

Palangi · #6 10-23-2008, 11:23 PM

Just get a bucket. It's really not a bad job if you can drain most of it before you remove the strainer. Make sure you have a socket that will fit before you start the job. It takes a fairly short socket.

TylerH860 · #7 10-23-2008, 11:34 PM

While I like the Kerry method, I imagine it will take a very long time to drain the tank. Siphoning seems to be faster given my clogged situation. Backing up one side on a ramp should help matters as well.

Yes, I need to get a hold of a 46mm socket, or 1 13/16 correct?

barry123400 · #8 10-23-2008, 11:47 PM

No the primary filter usually has an air bubble. If you mean the actual line coming in to the filter is not full that is different. What I find troubling is the switching of lines brought no relief. Ran exactly the same I assume. If so the lift pump itself is becoming suspect. Ingesting of air into the fuel line by the same token was also eliminated for all practical purposes by switching the fuel and return lines. So was an obstructed tank filter.

Your description unfortunatly already eliminates a retained vacuum in the fuel tank as well. Now an air leak into the primer pump might give you the symptoms as well.
The only fly in that ointment is it is after the primary filter. So even if it was leaking air that would not be reflected downstream. Looks like a weak lift pump more than anything by your description. I might be missing something or another as it is late and I am getting sleepy.

TylerH860 · #9 10-23-2008, 11:54 PM

I agree the lift pump may be the problem, but from the search I've done before posting this thread the same symptoms have produced by someone accidentally switching the intake and return lines.

I guess I will pull the line and see what happens... hopefully its not bath time.

JimmyL · #10 10-24-2008, 12:09 AM

Quote:

Originally Posted by daw_two

Tyler....which car?

The fuel sender is UNDER the first aid kit compartment in a a 300D sedan; remove 2 screws and then remove the first aid kit compartment.

The fuel sender for your wagon is under the black tray that is in the back of the hatch area.

Have you tried loosing your fuel filler cap? Maybe it has a vacuum on it.

The sender really doesn't matter, it's the strainer.

I haven't removed a strainer in a sedan, but I've noticed that it has a fuel line in the middle of it. Just unhook that line from where ever it goes and let that drain into a bucket. Then you can use your 46mm socket to remove it.
If it is clogged, or there is gunkage in the tank then I imagine your fuel filters are compromised again.
So, drain and clean tank and strainer, replace filters and you should be golden.......
[a wagon strainer is so much easier to remove]
To throw daw a little luv, whenever I remove and clean a strainer I also remove and clean the sender. He let you know where it is.......

BTW, do you have the old style primer pump? You should update to the newer style if you still have the old one. I've had the new style leak, but it didn't suck air for whatever reason.....

TylerH860 · #11 10-24-2008, 12:14 AM

Got my bath...

The fuel is flowing out of the tank like Niagra falls.

No trickling, no small stream, but a full flow.

Oh boy...

barry123400 · #12 10-24-2008, 12:17 AM

Quote:

Originally Posted by TylerH860

I agree the lift pump may be the problem, but from the search I've done before posting this thread the same symptoms have produced by someone accidentally switching the intake and return lines.

I guess I will pull the line and see what happens... hopefully its not bath time.

The station wagon tank is configured differently than the sedans. So a different situation or effect could result versus a sedan type tank.

I had to revise my post when I found out you had eliminated tank vacuum as a possibility already. Then I noticed it was a station wagon. At that point I realized I was tired. I suspect you will get good flow from the fuel line at the tank. I too would still check it though.

Another component of my earlier guess was the head of fuel or pressure present on a much deeper sedan tank until it got low. The depth of a station wagon tank very much lessens that possibility as well. Reduces the lift pump possibility a small to medium amount as the cause.

JimmyL · #13 10-24-2008, 12:17 AM

Quote:

Originally Posted by TylerH860

Got my bath...

The fuel is flowing out of the tank like Niagra falls.

No trickling, no small stream, but a full flow.

My prostate should work so good.........

BTW, it is his sedan....

TylerH860 · #14 10-24-2008, 12:23 AM

Yes, it is the sedan...

Jeeze, brain fart... Of course its rushing out of there now. I have rear of the car way off the ground up on my ramps

The hand primer is fully functioning now, further pointing to the strainer I suppose.

I seem to always over think things.

JimmyL · #15 10-24-2008, 12:27 AM

I have yet to have the strainer cause a problem. I've never really pulled out one that was very dirty. Maybe I've just been lucky though. Haven't had the horrible fungus amongus........