I've got almost 3/4 of a tank and no fuel coming to the prefilter.
My son was driving and lost power gradually like clogged filters. He changed both spin on and prefilter and used the primer pump, as did I, and no fuel coming to the prefilter. Any ideas? He's already blown back both lines to the tank in case the tank filter was gummed up. Still no fuel in prefilter, And the car won't start obviously.
Help? ideas?
Mike

the tank strainer is most likely clogged. there is an article about removing the fuel tank but you do not need to do that much, drain off the fuel and replace the strainer at the top.

http://www.peachparts.com/Wikka/W123FuelTank

if you want it to be super clean you could yank the whole think and have a radiator shop clean it.

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'81 300D - swapped to a 617.951 turbo motor with a 150 amp alt.

thanks. I'll have a try. ON my wagon, the filter was on the bottom and it was easy. Tank exposed under the car. Does the fuel tank in the sedan sit behind the rear seat inside the trunk?

Try switching inlet and return lines in the engine compartment. If the tank screen is plugged you should get fuel thru the return line.
Have you confirmed that there is not a vacuum in the tank?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Is this really a 1985 240D?.?..... Non-US spec car?

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1983 123.133 California
- GreaseCar Veg System

yes, 85 euro, pain in the butt finding the right parts. No listings here in the states so it's always a guess and try with a new broken item.
My son said he reversed the lines, but I'm gonna have to do it myself. Just wanted all ideas before I go out there and start dicking with it.

good to know about reversing the line to see if it is the tank filter.

and yes sedans fuel tanks are mounted behind the rear seat. there is actually a metal divider wall connected with the rear shelf, it is under the rear shelf/seats

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'81 300D - swapped to a 617.951 turbo motor with a 150 amp alt.

It's pretty easy to get the tank out -see the FSM. I've taken mine out of both my W123s and cleaned them out. Doesn't hurt.

Some of the later models have a very fine mesh tank strainer, and that gets bunged up quick easily, especially if you have algae or are using WVO.

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1983 240D Silver/Blue "Sadie", unknown miles. 100k miles on WVO single tank, converted to 2 tank about 10k miles ago, FPHE, Injector Heaters, Aux Fuel pump. Alcohol/Water injection. Frantz oil bypass filter
1992 300D 2.5 Turbo Green/Tan "Jade" 267K miles Stock.
1992 300D 2.5 tan/tan "Rocky" on 2 tank WVO. Pressure actuated Turbo "rat's nest" surgery completed. 197k miles

Before pulling anything from the tank I would try some biocide. It could be plugged with bacteria.

Tom W

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

who sells biocide? and what are some or any popular brand names please.

"biobar" commonly sold at tractor, truck and marine suppliers.

Tom W

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

OK<
I put biocide in the tank, and let it sit a while, weeks! I've blown back to the fuel tank from the supply and also from the return from the engine side with both disconnected and I got fuel each time returning from the tank. (cap closed). I've hooked up a separate fuel supply, ala the diesel purge unit, and I get the car to start only breifly with a thimble's amount of fuel. This is also the case when I had the car's fuel supply
connected after priming the fuel line with the factory hand pump.

I wondering if there is a possibility of the injection pump or injectors being gummed up and keeping the car from starting.

I was going to pull the strainer from the tank, and also check for collapsed hoses from the tank, but with the car not running on the separate fuel source, I'm now under the impression it's foward of the fuel lines.
Any ideas out there? Can I blow compressed air into the injection pump? and through the lines into the injectors without causing damage?
Mike

UPDATE:
I removed the return line cigar hose and put a separate hose on the filter housing return into a catch jug. I blew compressed air into the return line as my helper cranked the engine. No luck and only a dribble of fuel coming out of the filter return into the jug. Perplexed, I did nothing. A while later I re-installed the cigar hose to it's original position. I tried cranking about 3 x. Each time the engine would run a bit and conk out. 3rd time engine caught and ran but very slow. In the engine compartment, I tried to rev the motor. It sputtered and would not rev for a while. Finally it rev'd up and blew a cloud of smoke. I let it run and later shut it down. It now starts and runs fine. I'm guessing that 2 things happened. 1. my son filled the spin on filter with engine oil, and 2, that he had a air bubble in the line, from not filling the spin on completely. I don't have any idea what caused the engine not to rev up, but it's now fixed.
Some one else might need to try the compressed air into the return fuel line like I did. This pressurized the supply and hopefully forced out the air when the engine was cranked.
mike