'79 300D >> Weird Power Loss Situation Cropping Up.
 

OK... recently my 300D has been doing a strange acceleration thing where it "bogs down" going into second or third, and can have a heck of a time getting up this hill on the way to work.

I thought of the little plastic fuel filter and checked that and found a bunch of black grime clogging it, so I thought changing that would solve my problem. I changed it, and for a day or so thought I was back to normal, but now it seems to be the same again. I checked the filter again and while there is a little bit of the black stuff in it, it doesn't seem like it would be enough to cause this bog-down thing....?

I'm wondering if the switch to partion bio-diesel is starting to eat away at my old fuel lines? I'm in Oregon and I think we're mandated in Portland to have B5 (5% bio/95% petro?) at all pumps. Do you think this could be the source of my power loss? Could enough of this get past my filters to clog the injectors? Oh... and should I check the other filter... the "secondary" as it's called I think?

Any other ideas on what to check on this? The only other thought I have is perhaps it's a new vacuum leak and my transmission is now acting up and bogging down on the shift pattern? I can sort of kick it into the next gear by quickly taking my foot off the pedal, then back on... it kicks in to the next gear, but the engine feels like it's "wobbling" or something?... not firing on all cylinders?....

Thanks all....

Yes replace the secondary I had similar problems to yours. While i'm not too sure about bio, The bio will not plug the injectors, it will just harm old rubber fuel lines, to run bio, I believe, about B20 you need the viton lines; which essentially, is a higher grade of industrial rubber.

Hope that helps!

Clogged Fuel Strainer in bottom of Tank
 

http://www.peachparts.com/shopforum/alternative-fuels/245740-clogged-fuel-tank-strainer-wvo-gunk.html?highlight=clogged+fuel+strainer

See picture in reply #7 here:
http://www.peachparts.com/shopforum/diesel-discussion/235674-ran-out-fuel-gauge-just-below-1-4-tank.html?highlight=clogged+fuel+strainer

And this one shows you how to drain the Tank without getting covered
in Diesel:
http://www.peachparts.com/shopforum/diesel-discussion/236170-time-my-diesel-shower-perhaps.html?highlight=clogged+fuel+strainer

Try a biocide in your tank. It sounds as if you have bacteria there. The biocide will kill it and it will come through your filters and burn out.

To prove if the problem is in the tank strainer, swap the supply and return fuel lines in the engine bay where the rubber fuel lines connect to the steel ones. This will bypass the strainer and allow non-strained fuel to go to the the prefilter. Any improvement in performance is likely to be due to the strainer blockage being bypassed.
In this situation, the prefilter may block rapidly, so be aware of this issue.
If you want to empty the fuel tank, you can pump from the return line as it goes to the bottom of the fuel tank.

Regards,
Tony

Start with the easy and obvious first. First change your spin on fuel filter. I'm willing to bet that it's clogged, and it's not the tank strainer. Your symptoms are classic clogged fuel filter symptoms. If that does solve the issue then pursue the tank strainer.

So.... fuel supply blockage it is....?
 

Hey All,

Thanks for your opinions and suggestions. It seems that nobody thinks the problem could be other than the fuel supply....?

I'm wondering how the crude I'm seeing could be black if it's a matter of my tank having growing organisms in it? Should I not check the secondary filter also.... (after the primary, little plastic one?) .

Secondary "Spin On" fuel filter...?
 

..... also.... if I want to check out my secondary fuel filter.... how do I go about that? Do I need to drain fuel out of it somehow?

Is the tank "strainer" right under the rear fuel tank? Reading some of those other posts, I'm reminded that I >did< happen to change my fuel cap a couple of weeks ago to a locking style key-cap. It seems to my memory that my problem might have started appearing the same time that I did this. I'll have to take the cap off and see if that changes anything.

I do want to check the secondary and probably the tank-strainer, as the black crud that I was seeing in the previous primary plastic filter was disturbing. The plastic clear thing was completely black!

The secondary filter and spin on filter are the same thing. There isn't a way to check it. You can only replace it. I would start with that. The black crud could just be the build up in the tank being broken loose by the biodiesel. But it could also be fungus or bacteria.

Your stalling issues could be vent related. After a long drive pull the fuel cap off. If you get a big suction noise you have vent issues. The caps on these cars aren't vented. There is a seperate vent line under the car. If you crawl around and follow all the steal lines. One has a little bell shaped rubber piece on the end. They tend to get clogged up with mud.

The tank screen is on the bottom of the tank. It's the big 46mm bolt head you see. You can trouble shoot wether the screen is clogged or not but switching the supply and return lines in the engine bay. If the issue goes away then the screen is plugged, if not then it's something else.

Again I urge you to change the secondary(spin on) filter before bothering with anything else.

Any other ideas on what to check on this? The only other thought I have is perhaps it's a new vacuum leak and my transmission is now acting up and bogging down on the shift pattern? I can sort of kick it into the next gear by quickly taking my foot off the pedal, then back on... it kicks in to the next gear, but the engine feels like it's "wobbling" or something?... not firing on all cylinders?....


Hi
If you 79 300D is the same as mine it does not use vacuum for the tranny, it use's linkage, The linkage can be adjusted.

Secondary filter not cleanable?
 

I thought that the secondary fuel filter was a metal type thing and that you could clean it up and just re-use it? I guess that's only in the fintails and older models?

How much should I be expecting to pay for a new secondary? Is it something standard I can get at most big chains, or specialty/dealer only?

Also..... will there be a lot of fuel in the secondary filter that will spill out when I go to open the thing up?

Thanks all....

Fuel System Difficulties
 

All good suggestions in the Replies Above.

There are no OE,OEM type Fuel Filters that are "Cleanable", onetime use only.

Representations of fuel filters (With MB parts numbers) in picture #4 below

EDIT: (Fungus,Fungus,Fungus.)

You have a Microbial Infestation...it is clogging ALL your fuel filtration system filters.
THAT'S THE BLACK CRAP YOU'RE SEEING IN YOUR SMALL PRE-FILTER.
You can throw nice clean new fuel filters at this problem until you run out of money,they will only continue to clog.
(You MAY have to R+R the tank strainer...Try theStartron for a couple of days FIRST).
'Follow TonyFromWestOz's suggestions if you
have to drain the Tank to be able to R+R tank strainer.

Some people have gone to the measure of removing the Tank and having it
cleaned(or doing it themselves).Try the Startron FIRST!

You MAY also have to remove your fuel Gauge Sensor from the Tank and
Dis-Assemble and clean it. IF the Startron does not take care of it.

Pick up some Startron @ a West Marine, pour 4oz or so in your fuel tank:
(you can pour the whole 8oz in,it will not harm anything)
It sets up an Enzyme factory that "Eats" the Algae' s innards.
It will kill all the Bacterial Infestation and reduce it to small enough particles
as to allow passage through the filters and harmlessly burn up in the engine.

Tank Strainer Picture(#3 in the collection below)
"BAD"(Infested),on the Left ... GOOD(Clean), on the right

It's not algae. Algae needs light to grow. What grows in your tank is fungus or bateria.

"Algae, microbes, and water" (from: Wikipedia)
 

"There has been much discussion and misinformation about algae in diesel fuel.[citation needed] Algae require sunlight to live and grow. As there is no sunlight in a closed fuel tank, no algae can survive there. However, some microbes can survive there, and can feed on the diesel fuel.

These microbes form a colony that lives at the fuel/water interface. They grow quite rapidly in warmer temperatures. They can even grow in cold weather when fuel tank heaters are installed. Parts of the colony can break off and clog the fuel lines and fuel filters."

Thank You,Biodiesel300TD

spin-on secondary filter spillage?
 

Hey All, thanks for the continued help.

Nobody has been able to tell me what to expect if I open up the secondary fuel filter to change it out? Is it full of fuel-oil after the engine has run and then been stopped and sitting for a while. Or does the fuel-oil tend to flow out at stop and thus be pretty mess/spill-free when opening it up?

Thanks.