Where is my fuel pump screen & check valve (pic)? Also, safety tips? - PeachParts Mercedes-Benz Forum

caleboar · #1 03-06-2008, 07:50 PM

1976 450SE

I am troubleshooting my hot start issue and have a few (newbie) questions:

1.) How many fuel screens does my car have? I believe there one in the bottom of the tank and one in the fuel pump? Using my pic, could someone please direct me as to where the screen in the fuel pump is located. I plan on inspecting & cleaning this screen this weekend.

2.) Where is the check valve located? i'm guessing on one end of the fuel pump. I've purchased a replacement check valve for installation.

3.) There has been kind of a "whining" noise located in or near that rusty apparatus to the left that joins the fuel pump & filter...is this normal and/or is this piece cleanable, etc?

4.) Finally, besides unhooking my battery and catching any gas in a bucket, are there any common sense safety tips while unhooking some of these fuel hoses? (I'm also replacing my fuel accumulator). Also, will all the gas that's currently sitting in my tank drain out if I undo the pump and accumulator? I'm at about a 1/2 tank now.

Thanks in advance and please excuse my novice questions.

cheapold280ce · #2 03-06-2008, 09:45 PM

[quote=caleboar;1784797]1976 450SE

I am troubleshooting my hot start issue and have a few (newbie) questions:

1.) How many fuel screens does my car have? I believe there one in the bottom of the tank and one in the fuel pump? Using my pic, could someone please direct me as to where the screen in the fuel pump is located. I plan on inspecting & cleaning this screen this weekend.

Theres the tank screen It's inside the tank you follow the other hose on the rusty apparatus and it will lead you to it. 19 ot 17 to remove hose and Socket for strainer (search forum for size).

2.) Where is the check valve located? i'm guessing on one end of the fuel pump. I've purchased a replacement check valve for installation.

It''s in the fitting holding in the banjo connection at right side of pump.

3.) There has been kind of a "whining" noise located in or near that rusty apparatus to the left that joins the fuel pump & filter...is this normal and/or is this piece cleanable, etc?

Noise is fuel pump and it's normal if not to loud.

4.) Finally, besides unhooking my battery and catching any gas in a bucket, are there any common sense safety tips while unhooking some of these fuel hoses? (I'm also replacing my fuel accumulator). Also, will all the gas that's currently sitting in my tank drain out if I undo the pump and accumulator? I'm at about a 1/2 tank now.

If you are going to replace or clean the tank screen. Get a three 5 gallon gas cans. Remove the return line from your fuel distributor. Attach a hose from the return line at fuel pump to the gas tank. Jump fuel pump relay and empty tank. Remember to change the gas cans as they fill up.
When tank is empty then work at changing and cleaning stuff.

caleboar · #3 03-07-2008, 03:59 PM

Thanks for the help.

So is there another screen located in or near the fuel pump, in addition to the tank screen?

cheapold280ce · #4 03-07-2008, 05:08 PM

No. I was just letting you know the tank screen is inside the tank. There are other small screens which are usually not replaced. They include screen at intake fitting to fuel distributor, screens at each outlet of fuel distributor, screen at inlet to WUR.

wbain5280 · #5 03-08-2008, 01:39 AM

The gas tank is above the rear axle and between the rear seat and the trunk. There is a removable divider at the rear of the trunk. This means that the pump is gravity fed from the tank and the tank must be empty to change the screen. You can also clamp the fuel hose with a proper fuel line clamp and work on your fuel pump package. Considering the car's age, you may want to consider getting all new hoses, clamps, filter and accumulator, which looks like the rusty disc shaped object in your picture.

Remember, gasoline is dangerous and you need to respect it. You can pump out the tank but make sure you have an assistant to help you with turning off the key so you can switch gas cans etc.

check the buy parts section of this forum and there is also a w116 site with the repair manuals.

http://handbook.w116.org/matrix6.htm

Blue 72 250 · #6 03-08-2008, 11:03 AM

Make sure that you do the work outside. The fumes will build up in a closed space and you will not like the result.

ctaylor738 · #7 03-09-2008, 08:50 PM

For a hot start problem, I would not mess with the tank strainer. The cause is usually the accumulator. When changing it, you can minimize the amount of gas spilled by clamping the line from the tank. Most good parts stores sell the appropriate clamp. I have had success clamiping usiing vise grips with tape wrapped around the jaws to protect the gas lines.