Question about 1985 Mercedes-Benz 300

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84 Mercedes 300

I just replaced the fuel filters they were really dirty, runs on biodiesel i still can't get it to start please help

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  • m_nnoxid Feb 10, 2009

    The Bio is mixed it is really cold where i am but i put more reg diesel to make it about 50/50 mix but it still wont start i was thinking about bleeding the gas line just in case it is clogged or has hardened in the injectors pump anymore input would be great- Thanks!



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When you say 'biodiesel' do you mean true bio that is a mixed product or a combination of vege oil/diesel or pure vege oil? What is your daily air temp? Pure vege and even some combos with a high percentage of vege will thicken up in your injector pump, lines and injectors. If you're in a cold climate, I suggest moving the vehicle into a garage (preferrably heated) warm the car up as much as possible, using a tarp and heaters if nescessary. (Don't start a fire!) There also is a bolt on top of the water seperator (looks like a spin on oil filter in front of the engine) that you can loosen while you crank the engine until fuel comes out of the bolt hole. This removes any air trapped in the line. Hopefully you filled the H2O seperator with diesel prior to reinstalling it.Don't forget to add regular diesel to the fuel tank to thin out the vege, if that's where you put it. If you think that the mechanical fuel pump is giving up the ghost, I suggest trying an inline fuel pump from an early '90s Chevy diesel. It's electric and can be placed on the firewall near the inline filter, just bypass the mechanical and give it a battery source that is keyed.

Posted on Feb 06, 2009

  • mmmsaab Feb 10, 2009

    I believe that your car is non-turbo. Here is what i would do if it were mine:

    Your car has glow plugs... have you tested them? I'm not exactly sure on your car's removal of the glow plugs. On mine, I remove the intake that goes over engine and then I can get to glow plugs. Remove one,(at least). Take a set of jumper cables, connect one set of +/- ends to battery. Connect the - side of the other end to the threaded part of the glow plug, using jumper to now hold glow plug. Touch the + to the tip of gp where the electrical wire was connected. The gp should get hot and turn red IMMEDIATELY. If not, it's toast. Replace all that are bad and try to start. Continue with following instructions if engine fails to start.

    Take a gallon of diesel and store it in the house overnight bringing it's temp to around 65-70 degrees. Remove H2O seperator, dump out whatever fuel is in there, refill with warm diesel and replace. Remove airfilter cover and spray in some ether/starting fluid(not too much, a few quick squirts is all that's needed) and crank engine. Engine should catch on ether and start drawing fuel through injector pump. The warm fuel and the draw from the engine should free up any thickened fuel. Let me know if this helps.



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