My 1984 300D turbo seems to run okay when cold. After driving about 10 miles it starts to lose power and not respond to the accelerator. As I continue to drive it gets worse and worse - shudders and shakes for a while and finally stalls out. If I let it sit overnight it runs fine for ~10 miles again. If I only let it sit for an hour it will start, but it will be underpowered and shaky.

I described this to a mechanic and he said he wanted to change the in-tank fuel filter ($250). If that would fix it I'd be happy enough, (by the time I buy the special wrench, the new filter, beer for my friend, sacrifice my weekend, $250 starts to sound not so bad).

Does it sound to you like the mechanic's diagnosis is correct? Do you think that changing the in-tank fuel filter will fix it? I have my doubts 'cause it only happens after I've driven 10 miles and the car is warm. Why wouldn't it be all the time?

Please help me! Lately I've put a few requests for advice on the forum but gotten no responses. Am I posting these messages wrong?

morav@hawaii.edu

 

The in tank strainer is a possibilty. Have you changed the main fuel filter, and the primary fue lfilter? Also look for ANY leaks they will allow air into the fuel system and cause the symptom you describe. Also check the fuel lift pump, it could be getting weak. Put a clear hose between the lift pump, and the fuel filter, run the engine, and look for air bubbles going up the clear hose. That will indicate a leak, then it's a matter of finding said leak

 

Did you solve the problem?

 

I got the strainer out with much difficulty and a nice bath of diesel fuel. It was about 50% clogged with black slime. I changed the filters under the hood. I put a fresh tank of fuel in and added "Soltron" supposedly the same thing as "Startron" - miracle in a bottle. Car ran fine for the usual 10 miles then started sputtering and stalling again. This time I had a pretty good idea about what's going on so I pulled into a lot, took the primary filter off - clogged with a different color gunk, blew it out, reinstalled it, and the car started. I suspect that I just have so much crap in the tank that unless I clean the tank I'm going to have to go through this a lot (my friend suggested routing the fuel line through the passenger compartment so I could change the filter without getting out of the car. He's hilarious...). I'm thinking of putting together a system to recirculate the fuel through a big external filter overnight to try and get the gunk out.

 

If you do that pull it out through the return line, and put it back in through the fill port. Let it run over night, what you have in the tank might be algae. Get a good biocide for diesel fuel, put it in the tank, and keep a couple of fuel filters on hand for a while, you'll probably be needing them.
The best way to remove the algae is to take the tank out and carefully clean and flush it.