Need Diagnosis Help on very confusing Fuel Problem

[Gray 1985 300D]

Hi,

I purchased an 85 300D that has approx 220k on it.

When I test drove the car, it felt sluggish, so I immediatly changed the primary and secondary filters. It seemed to work fine for a day or so, then it began to get sluggish again, which means just lose power on the highway from say 40 mph to rough ride, to finally stall.

I didn't drive the car for a couple of months, and when I started it, it was fine for two days!

However, I just started using this car again, and I literally put my foot to the floor to get the car up to 20 MPH, with no power and eventually stalling out. I can pull over to the side and just race the engine in neutral and see it go up to 3200 rpm's and then, without moving the accelerator just go down to 0 with the engine stopping.

I took the car to my mechanic, and he checked the line at the base of the tank, and it was plugged, he then completely blew out the fuel lines from front to back and then finally the tank.

When the tank was drained, the fuel was black, and towards the end was brown and muddy. He then took out the screen in the tank and blew the tank out with the high pressure air compressor (with the tank screen out) and a tremendous amount of sand came out of the tank as well! He then put in a new screen.

Now, after all this is done, and the fuel is changed, the car barely starts and doesn't move after I put it in gear, just dies. (Let me mention that I drove it the mechanic even with all the sand and black fuel etc, before it was cleaned)

PLEASE, I need your help on what you think the problems may be. My mechanic thinks that it could be a blocked injector pump, because he kept opening the tops of the nozzles when the car was running and the #1 and #5 injectors were sometimes getting fuel and sometimes not, or low fuel.

Please let me know what you could think this could be. I'd really appreciate it. Thanks!

Get a bottle, fill it with fuel, stick the supply and return lines into it and see if your problems go away. If it does then it may be time to do a thorough cleaning of the lines and clean the tank with it out of the car.

[rrgrassi]

Yep, Do what Forced suggests. Also check your primary filter again. It traps more dirt than people realize.

[Brian Carlton]

A failing fuel pump will also cause the same symptoms.

[TheDon]

you mean lift pump, right Brian?


do as the other have said and if it turns out so get some biocide from your local boating supply house or West Marine and do what the bottle says to treat the fuel. You might have to drain the tank and clean the in tank screen.

If that does not solve it and it is an fungus issue you will have to remove the tank and have it steamed to start fresh.

[Brian Carlton]

Originally Posted by TheDon

you mean lift pump, right Brian?

fuel pump.......lift pump.......call it what you want. It maintains pressure in the IP to allow sufficient fill of the elements in a very short time period.

[minimike1]

Check your transmission fluid level!

[barry123400]

Your new filters probably caught a lot of the tank mess. That might be my first move.

Or remove the tank and really clean it. Blow the lines out again. I might even put a solvent into them and let them soak a little first. You have to have a known base line to work from or you may just find youself on a merry go round.

I think the lift pump can be removed and cleaned out as well. I doubt anything major has made it into the injection pump yet.

At least there are not many if any parts required to do a real clean up. Simply dirty and time consuming work. Plus you eliminate the possibility of the problem surfacing again someday at a most inoportune time.

[myssrhl]

My tank screen was solid crap in the 300cd.

Cleaned it, easy to do, runs like a scalded dog.