Didn't believe her..
 

My wife kept saying her car was losing power. She is a very "gentle" driver. I thought perhaps she was not nailing the throttle hard enough. She also complained about roughness at idle. Everytime I drove the car, it was perfect.I drive all my vehicles in a "spirited" manner. I told her "unless I can re-create the problem, or you can, I cannot fix it". Well today, I took her car on a bunch of errands. It did indeed misbehave. I was going along OK up a slight incline. The car would not respond to the throttle. Mashed it and got a downshift but no acceleration. Stopped at a stop sign. Took off, and did an "italian tune up". Everything was fine. Did the rest of my errands. Pulled into the garage, but the car idled rough. Went back out and all was fine again. I suspect the tank screen. Changed the filters about a month ago. They look OK. Fuel sender stopped working last month and I cleaned a good bit of black stuff out, and got it working again. Added a can of Seafoam two days ago. Think that will clean the tank screen, or am I going to have to make a mess and pull it?

Sounds like you need a trip to Dr Phil for starters !! :) A sorry & a bunch of flowers may go a long way to fixing things more so than seafoam !!!

If you have Black Biological Gunk in your tank, You may need to replace the filters again soon if the seafoam doesnt break it down.
When the gunk has happened to me I have found that blowing the fuel line from the tank out with compressed air, that is back blowing from the primary filter helps in the short term. Only do it with the fuel cap off and less than half a tank.
Good Luck !!

Thanks
 

From OZ,:>) I want to go there someday. Thanks for the great idea. In the morning I'll fire up the compressor and shoot some air through that screen. If she can then have a couple "normal" days of driving after that, I'll know for sure that it's the tank screen. I did a fix on my TD fuel gauge, clogged with black stuff , removed my tank screen, only to find it clean, after dealing with diesel down to my elbows,hehe. I don't mind fixing a problem, but checking a problem that involves a mess... hehe, I don't wanna do. I'm commited to keeping our cars going 'till we croak though. My TD has 116,000, her car has225,000. I'm getting a bit old, so I don't want to do difficult, messy, diagnostics. Popping a bit of air through that screen will tell all :>).

It sounds like you need to change your fuel supplier.
After you blow the line out you will need to bleed the line. Depending on how much fuel is in it, gravity often does most of it. Facing the car down hill also helps. Something like a mighty vac can be useful.
I gently blow a little air down the return line with the filler cap back on, even though most of the air will be leaking out the tank breather ( you will hear it) it often gives just enough pressure to bring the fuel up the supply line, so I can then reconnect it to the primary filter.
Or you can just prime it with the primer pump.
Good Luck !!

Clogged tank screen
 

Bit the bullet, pulled and cleaned the tank screen. It was VERY clogged with black stuff. Couldn't even use the "return line" trick to pump the tank dry, as fuelbarely dribbled out of the cigar hose due to the clog. So I put a big tub underthe fitting and just let it all go. Now I have about 3 gallons of dirty diesel I don't know what to do with. I changed the filters and it's running great. Does diesel fuel evaporate quickly?

Glad you found the problem.
No, diesel fuel is slow to evaporate.
Filter it through a coffee filter, put it back in the tank, add some Soltron and burn it.

Will do CR
 

After the hood hinge pocket leak, and reading your posts on other things, I've come to trust your advice. Coffee filter it is. I really wanted a way to use the fuel, save taking it waay out to the dump to be recycled. I thought about ways to filter, but all involved more work than I wanted to do. I can make a big buckner funnel out of stuff in the shed with a coffee filter as the media pretty easily. What sort of micron filtration do I get with a coffee filter? I know it's only 3 gallons, but is the fuel we get out of station pumps all that clean anyway? It must have a bit of junk in it, or no one would need fuel filters.

look up startron fuel treatment. you're going to need to treat your fuel tank, or it will rapidly re infest and plug up.

Infection
 

This has all turned into the kind of searching I really love. These are questions I'd love to see answers to. The car has 225,000 miles. Could it have gone so long without an infection, only to get one in the last 2 months? Is this a chronic infection? Say low levelfor 26 years, or does it happen with one tank of bad fuel? I've read many negative things about additives of any sort. Since we went from 1984 to 2010 with no additives, do I now spend money for an inoculation, or just wait another 26 years. I know this diesel bacteria is real, but on an epidemiological level, are we talking about a real infection that you catch at a point, or more like gasser "varnish" that forms in old gasoline? Since I've removed most of the fuel, and put in fresh, that this infection will in less than 20 years, come back?

One tank of bad fuel from a station that you dont normally go to will do this. I would not bother with filtering & re-using the fuel in the car. If you have a wood heater, use it to start your fires for a while or for cleaning motor parts, or killing weeds.
To help cure the infection, it is best to start with fresh clean fuel. Find a station that has a high turn over, lots of trucks & you can avoid a repeat.

You cleared the filter but I don't read anything about you cleaning the tank or killing the microbes. I went 25 years without additives also but I now add 12 oz of TCW 2 cycle oil and 2 oz or Startron on at every fill up (fuel quality has gotten worse in the last 25 years). I don't know what the micron rating is for coffee filters - probably depends on the brand. You just want to get rid of the biggest clusters. The Startron will do the rest.

Infection
 

On epidemiological level how virulent is this diesel bacteria? Could we have really gone from 1984-2010 without an infection, only to have it surface now? That's what I mean. Is this infection present in all diesel at a low level that builds over decades, or can you, like cancer, avoid it with luck? Is it more like cancer, or the flu? My gasser cars and equip,were subject to "varnish" without Stabil additive due to infrequent use. Do I have an infection that needs prohylatic treatment, or chemo like cancer? Or Kill it all and it's gone?I've never believed in chiropractic, I look at that practice as I see most fuel additives. If I use the leftover fuel from my wife's SD, filtered properly, in MY car do I risk an infection? Do these black deposits happen over decades or months?

I have to agree with Layback on the bacteriological infection. Probably fueled at a station that had the bacteria. The antibacterial suggested should do the trick but... you might have to change the filters a few times till things clear up.
To avoid the problem, as already suggested, go to high volume fuel stations. I always go to truck stops; they almost always have the best fuel.
As for filtering and reusing the old fuel... you can't really infect an already infected system. If you want to use the fuel, you could let it sediment then pour the more or less clear fuel thru the coffee filter I guess.
I would NOT take fuel from a car with a bacteriological/algal infection and put it in a car that doesn't have such an infection. Filtered or no you are only asking for trouble.

Finally, does the bacteria/algae whatever develop over years... I suppose it does like any life form. May be some use for it. Maybe it's a derivative of the bacteria used to clean up oil spills?

The sludge is not algae, bacteria, or alive:

http://dieselfueldoctor.com/solutions_explained.html

Well, I had my sending unit out not too long ago and there was very little black crud on it.

In fact I'd say it was more of a very small film. I could remove it with my fingers and a paper towel.

The condition of my tank was also relatively clean.

My car sat for 10 years with a full tank of diesel that was pumped back in 1999 from a truck stop. The fuel was still good and there was no build up of any gunk in it.

I feel like this issue is of the "your mileage may vary" type.