Fuel System Problem
 

So, my friend just bought an '85 300D and it wasn't running when she bought it, but the shop she took it to said it was the glow plug relay switch (or something to that effect). Well, they replaced it and it started up and ran fine, but was running very sluggish on the open road. Since the car had been sitting for a while and since the owner admitted putting straight WVO in it (60% diesel, 40% WVO mixture, according to him) I suggested she replace the fuel filters. So, we did and did everything according to the manual. However, when we went to prime the fuel lines and bleed them, no fuel was getting the engine. So, i suggested we add some more fuel and see if that helps. It didn't. Any thoughts? The two filters are currently bone dry. No fuel seems to be getting to them.

Variables:
- The hand pump seemed to not be working. Is there a way to troubleshoot this?
- The car is currently sitting on an incline. Could that be contributing?

Any help would be greatly appreciated.

Nice the Flying Spaghetti Monster. That was started by a guy here in Corvallis, OR!!:D

If they put veggie oil in the tank her tank screen could be clogged. Try switching the supply and return line in the engine bay and then use the primer pump and see if you can pull the fuel up to the front. If that doesn't help then her primer pump could be bad. Or the fuel lines are completely clogged with veggie oil.

But it was running before attempting to change the filters. How could that be?

primer pump
 

Does it have the old type screw down primer pump? Or new style black button. I've had the black one fail, you could pump all you wanted and nothing happened. I replaced it with older type.

It's a metal cylinder, so i think it's the screw type you describe. I tried screwing it both directions and it does nothing but spin. Methinks it's not working. What are my options?

It may have sucked the supply line dry, or maybe it finally clogged enough of the tanks screen to dry out the lines.

Put some clean diesel or ATF into a clear bottle. Then and put both the supply and return lines into the bottle and prime the system, and then see if the car will run off that. If it does then there is something clooged up stream from the engine bay.

The screw type primer pump should unscrew a couple of turns then you can pump it. It will turn all day when it is up, you have to push it down to screw it in. And it should be screwed in while the engine is running.

primer pumps seem to fail pretty regularly, not a big job to replace, if you point the car nose down on an incline and the tank has fuel, it should fill the primary filter.

Is that all you tried, spin the pump wheel? I'm hoping you also tried to pull up and down on it as well.

primer pump
 

replacement pictorial http://www.peachparts.com/Wikka/PrimerPump

Hmm, interesting comments. I will try a few of the things suggested in the morning. I am interested in more input, but you peeps have been very helpful thus far.

No, it's not all I tried. Of course, I'm more green on this car that the last car iworked on extensively - a '68 Mustang. I'm admittedly more ignorant about diesels, which is why I'm asking for help.

Swapping feed and return lines as per Bio... is a good idea, as is making your own fuel tank to isolate a potential problem as per Bio... again. The primers are old, and many leak and fail. Running bio diesel will speed up this problem, as it is corrosive to rubber and the internals don't last long. I've had five MBZ, have replaced all with the black unit, use old style for bio, it'll last a bit longer. Fuel pump failures are rare, yet not unheard of. But if you can't pull fuel from tank, doubt that's your problem. Clogged tank strainer more than likely, perform above tests, go from there. Good luck. Oh, and if Iraq is experiencing a civil war, we, by definition can't be involved, Steven Colbert.

Well, I attempted to switch the lines as per the comments above, but being the novice that I am it was not apparent to me after attempting this how the lines could actually be switched. However, after putting the lines back on, I began pumping again and the secondary filter started filling. Now it's filled, but the primary one is still bone dry and it seems like i pump into oblivion, but nothing more happens. Thoughts?

I believe they had you switch the lines to try to clean out the filter in the tank by reversing the flow of the fuel. If you are getting fuel to the prefilter then that was at least part of the problem.

You need to fill the secondary filter with fuel before you replace it. I always get it as full as I can when I change the filter. If you changed the filters on the car did you fill the secondary filter before you put it on?

Chris

Sounds like you successfully swapped out lines. NORMAL is upper steel line (near firewall) connected to, fat in the middle hose, return, lower intake goes to IP. Just swap rubber lines. And yes, per Bio... fill spin on with your choice of fuel, prior to installation, much less pumping involved.