Brilliant and abundantly clear! Just one followup Q: *You can take it from here, but I like to plug things before putting it back in the tank to check the low fuel light and the gauge. Gently tip it up and down to see if the gauge changes position. If so, you're done.*
Does this mean I should reconnect the plug and tilt the unit around with the key in the #2 ignition position and watch for changes in the gauge? Or should the engine actually be running while this test is carried out?? ALS On Mon, Sep 6, 2010 at 8:24 PM, LWB250 <lwb...@yahoo.com> wrote: > This is an easy one - > > If you pull the carpet up from the cargo area, you will see a large (3"-4") > plastic plug or cap. Pry this up and you'll be looking at the top of the > sending unit. > > Get a big crescent or channel lock pliers, and after you unplug the wiring > harness, unscrew the sending unit. > > WARNING! > > Remove it very, very slowly. Why? Because it will be full of fuel and the > bleed hole(s) in it are very, very small. Best to do this after you have > run the tank down as low as possible, as it minimizes the potential for a > mess. > > As you withdraw it from the tank you'll hear the fuel dripping, so be > patient and wait for it to stop. > > Once you have it out, find a clean place to disassemble the sending unit. > I like a workbench with a couple of junk towels I can put things on as I > remove them. > > On the bottom is a small (8mm?) nut. Unscrew this and then carefully > remove the metal disc that covers the bottom. After that comes off, there > will be a plastic disc that has all sorts of grooves in it. I'll explain > the reason for this later. > > Once the plastic disc comes off, the metal cylinder that is the outside of > the sending unit can be removed. Do this carefully. > > After the metal tube is removed you'll be able to see the business parts of > the sending unit - the float and guide wires. Get some good quality > electrical contact cleaner and carefully clean the wires, sliding contacts, > and brass disc on the bottom of the float that triggers the low fuel lamp. > > If either of the wires are broken, it's usually at the solder joint on the > bottom. Reflow this joint with good quality 60-40 solder, if possible. If > the wires are broken elsewhere, you may be out of luck, as they are nichrome > and a specific resistance to properly control the gauge. > > It sounds like your float is stuck or the wipers are making poor or > intermittent contact. A good cleaning will take care of this. > > After cleaning all the parts, reassemble in the reverse order. Take note > that the plastic disc on the bottom has to mate with the flat metal disc in > order to work properly. What this does is meter the flow of fuel in and out > of the gauge sender, so you don't have a wildly swinging gauge due to the > float moving up and down constantly. Fuel has to make it through this > labyrinth of passages to get in/out of the float chamber, so the level > changes very slowly. > > You can take it from here, but I like to plug things before putting it back > in the tank to check the low fuel light and the gauge. Gently tip it up and > down to see if the gauge changes position. If so, you're done. > > Dan > > > --- On Mon, 9/6/10, andrew strasfogel <astrasfo...@gmail.com> wrote: > > > From: andrew strasfogel <astrasfo...@gmail.com> > > Subject: [MBZ] W123 stuck fuel sending unit > > To: "Mercedes Discussion List" <mercedes@okiebenz.com> > > Date: Monday, September 6, 2010, 8:04 PM > > The fuel gauge in my 1985 300TD read > > "full" for 2 weeks while the miles > > piled on. For this period, the gauge returned to zero with > > the engine off > > and then steadfastly remained pinned at F with nary a > > flicker as the miles > > accumulated and the days marched by. Finally, at 353 > > miles I broke down > > and filled up the car with 14.6 gallons of diesel. > > That was Saturday. > > Today (Monday), with 150 miles having passed without a > > change in the gauge, > > bingo! - I noticed that the gauge had moved down to 3/4 > > full. Since then, > > the gauge has reflected normal fuel consumption and > > now reads < 1/2 full. > > Two questions: > > > > 1) Does this erratic behavior reflect a faulty gauge or > > stuck sending unit? > > > > 2) if the latter, how do I remove the sending unit to > > inspect and perhaps > > unjam or clean it? > > > > TIA, as usual. > > > > Andrew > > 1985 300TD > > 1983 300TD > > _______________________________________ > > http://www.okiebenz.com > > For new and used parts go to www.okiebenz.com > > To search list archives http://www.okiebenz.com/archive/ > > > > To Unsubscribe or change delivery options go to: > > http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com > > > > > > > > _______________________________________ > http://www.okiebenz.com > For new and used parts go to www.okiebenz.com > To search list archives http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com > _______________________________________ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
