W126 Not running right
 

I have a 90 300SEL that I only drive in the summer. When I brought it out of storage this spring it started right up and ran fine. When I jumped in to go for a spin and I stepped on the fuel it stalled and was very hard to start back up. It has been that way ever since. After getting it going it will not take fuel unless I feather the pedal. I have checked the breather and everything else for rodent nests and everything is clear. I assume it must be something electronic as it ran perfect when I put it away. What could change so quick over the winter? Anyone have any ideas what I can check? It is quite frustrating as I have no idea even where to start.

Could be a couple of things. Your fuel pump could be failing or the fuel filter is clogged. If the car is drivable, put a pint of seafoam in a half tank of gas and start driving. : ) You may also consider taking the air filter lid off and hosing down the throttle body with a carb cleaner. If the prob persist, pull the gas supply line off of the fuel dist and test for flow. Pump and filter are both easy to replace and reasonably priced.

Could the pump fail like that, all the sudden I mean? I do have a filter for it to try. It really isn't drivable as I am not sure if it will stay running. I have looked in the throttle body. It "appears" clean. The car has less than 110,000 klm on it

It sounds like a fuel delivery issue especially considering it has sat for period of time. If it has sat year after year for a few months at a time it is possible that even with low miles, the pump could have fouled and is failing. I have "rehabbed" pumps by taking them off and circulating seafoam through them, but that is not a particularly long lasting solution. They are easily accessible, under the right rear of the car if you need to replace it. You can detach the supply line at the distributor and jump the fuel relay and see if it is pumping and adequate amount. I dont know if you are going to get your hands dirty but that is step two. If it were completely dead it would not start at all.

No I don't mind getting dirty, I am pretty good with the older diesels but with the amount of sensors on the gasser not sure where to start.

First I would check the ignition, wires, cap, rotor and plugs.

When accelerating the mixture gets temporarily richer, bad ignition fails then.

Rob

I would check these as well but your condition sounds fuel related. If the cap/rotor/wires/plugs were the culprit, it would not have started and run fine and then immediately failed. Typically these parts deteriorate over time. That said, if they have not been replaced in the past 30K miles, I would put that on the list of to dos.

Well they were replaced awhile ago. Very good quality wires and related parts. Like I said it worked perfect the year before when I put it away. I honestly think it may be a sensor or something electronic/fuel, something like that.

We have a 88 300SEL that was my car, now my moms... it did the SAME thing! I drove it to a gas station back in July - it was running perfectly, filled it up, then it would not start at all. We had to have it towed home. Next day the car was trying to start (see video below) and following days we were finally able to start it, but it would miss, sputter and stall on acceleration. One day we started it... it idled for 15 minutes just fine, but when we would press the gas, it would stall or start to miss and splutter. We checked the fuel pump relay (bypassed), that wasnt it. Checked this and that - was told it cold also be the fuel pump or fuel filter. Finally someone told my dad to check the ignition coil. He took one off of my 72 Chevy wagon and used it long enough to see if you can believe that and sure enough, it ran perfectly. $105 later for a correct coil for the car and it has ran perfectly ever since. We also did replace the rotor button I think and I replaced the spark plugs after that.

Not sure if this is your issue or not, but just wanting to relay what the issue was on our 300SEL.

Here is a video I had a neighbor do back when it was having the issue since my camera battery was dead. He has a W126 and had been helping me w/it. This was back when it would only try to start... we had finally got it going after this, but it still would miss, sputter, etc.

Click on pic for the 2 minute video.... see if this is how yours is doing.

http://i39.photobucket.com/albums/e1...s/th_018-1.jpg

I'm wondering if my Autozone replacement ignition coil may be causing my warm start issues? I notice my daughters '87 w124 cranks a lot stronger than my '91 300e. She has an aftermarket battery and I have a mercedes battery. I replaced the fuel accumlulator and it does start better. Was going to replace injectors next but maybe I need a real ignition coil or stronger amp cranking battery?

No AutoZone Electrical Parts For Mercedes
 

SPTT,

Write it 10,000 times on your driveway.

All the other issues: Different Battery(s) on Different Chassis [of different ages?]
(With who knows WTF for Service History or Climactic Conditions Endured ???)
(Of who knows how many miles?)

Are you seriously expecting anyone to sort through your "ShotGun" of Questions
Sanely???

Hey, Brotha we try our best,but nobody here claims to be Omniscient.

The FSM has a step by step set of procedures used to diagnose and repair
problems.
'Go outside the procedures and you're taking your chances on a sucessful
repair.
"Guessing" or "Throwing Parts At" are not part of any repair procedure.
[Except @ Stealerships,where they're "Guessing" with your Money...Until your
Lawyer gets through with them.]

Here's the Scoop:http://w124-zone.com/downloads/MB%20CD/W124/Main.html

Everything you need to know is there.
(Or on the SEARCH button marked ADVANCE)

I dont know, we needed one asap for my moms car so we had to get one at Autozone. Actually my dad went and got it w/o consulting with me. He has never owned a Mercedes before and he had done went and purchased it and installed it. I didnt have the heart to tell him differently. He was just glad it started. lol.

They would not have taken it back anyway. I think it was a duralast brand or something like that and it was $105. Kinda sad considering I could have purchased the Bosch unit on here for about the same price. :rolleyes: If it goes out, we will def go with the Bosch.

Mayhaps one of the Starters Brushes are worn???
 

Too Many Undefined Variables.
'Need to narrow the Blame to the appropriate perp in the parts chain by
EMPIRICAL testing.

I.E before you replaced the fuel accumulator ,did you test the fuel flow
and pressure?

(Is there a Yellow Light on your Instrument Cluster suggesting replacement of
Fuel Injectors?)

You know mine acts like the car in the vid. Mine will start though so maybe just a difference in the degree of failure of the coil. I can test the coil to see if it is OK as well as the Fuel flow and filter. It is also about the way coils fail, kind of all the sudden.