Doing diesel purge - "ran out of fuel"

[mikeyfev1]

I was doing my first diesel purge today on my 1985 300D KaliKar. I setup everything the way I thought it should be, started the car. All fine. Watched the return flow for a minutes, was pumping as it should. Pickup line deep inside the fluid - total of 1 liter in bottle.

Went for a short drive. Got about 3 miles away and I got "out of fuel" symptoms. Managed to get to my daughter's house, raised the hood and looked at my purge tank (engine was still running, but poorly). No return fuel coming out of the return line. No fuel in the primary filter! Engine dies.

So I started pumping the primer and after many minutes of this, still no fuel in primary filter. Can easily blow though primary filter and fuel line from filter into bottom of purge tank. About 1/2 liter of purge fuel remaining. Pickup line did not leave the bottom of the purge tank, the purge tank was held in place and did not go inverted.

Above and beyond "why did the engine stop fuel pickup" is why can't I prime the lines? What should I be looking for? I need to solve this problem first.

[toomany MBZ]

Perhaps a coincidence, the fuel return check valve failed?

[mikeyfev1]

OK, I went reading other posts on "fuel return check valve" and I also found references to poor idle, which I also have.

Where exactly is this valve? I kinda think some of the pictures were showing a banjo bolt on the engine block side of the IP pump? Just take this off, clean it out, stretch the spring to 27mm and replace? (If I have the type that can be serviced).

Could this be causing the primer pump to not prime the lines?

[tangofox007]

Originally Posted by mikeyfev1

What should I be looking for?

Either the suction or delivery valve in the fuel pump could be stuck. In the case of no suction, either the suction valve is sticking closed (unlikely) or the delivery valve is not sealing when closed. When a delivery valve sticks open, you can usually see the fuel move back and forth in the clear fuel line between the pump and secondary filter as the primer pump is actuated.

Or, maybe your primer pump simply doesn't work.

Originally Posted by toomany MBZ

Perhaps a coincidence, the fuel return check valve failed?

We must have a nomenclature disconnect here. Where is this alleged valve located?

[toomany MBZ]

Originally Posted by tangofox007

We must have a nomenclature disconnect here. Where is this alleged valve located?

Entirely possible.

It's referred to as a "valve" on the epc and a "fuel bypass valve" in the FSM.

The pics show where it is on the car.

Item #200 is part number 000 074 72 84.

[tangofox007]

Okay, that is essentially a pressure relief valve. It should have no impact on the operation of the fuel pump.

[mikeyfev1]

OK, so this means there is still no consensus on what I should do. I have a situation where I cannot prime my fuel system from a clear plastic bottle with diesel purge fluid in in. The intake hose (the hose to the primary (clear) filter) is in the fluid. Pumping for several minutes does not produce any suction. The primary fuel filter and the hose into the fluid is not clogged.

Any ideas?

[tangofox007]

Try priming by cranking the engine instead of using the hand pump. Crack the discharge fitting on the secondary filter to allow air to escape. Elevating the fuel supply will put gravity on your side.

Originally Posted by mikeyfev1

Pumping for several minutes does not produce any suction.

What version hand pump do you have?

[Fattyman]

Originally Posted by tangofox007

Try priming by cranking the engine instead of using the hand pump. Crack the discharge fitting on the secondary filter to allow air to escape. Elevating the fuel supply will put gravity on your side.

Tango has the right idea. Let gravity help you out. Your prime pump may be NG as well. If you crack the banjo bolt that is mounted on the filter housing, the opposite end the "check valve" fitting on the IP. That will bleed the air from the system. That fitting is the high point in the system and has a bleed hole to the secondary filter. This is where an electric fuel pump would come in handy. Otherwise you'll have to crank the engine. Loosening the injection lines on the injectors will also help bleed the air while cranking the engine. As soon as you get fuel coming out of them tighten them back up. Have fun.

[mikeyfev1]

Try priming by cranking the engine instead of using the hand pump. Crack the discharge fitting on the secondary filter to allow air to escape. Elevating the fuel supply will put gravity on your side.

OK, I will raise the bottle with the diesel purge in it. By discharge fitting on the secondary filter do you mean the fitting with the arrow pointing away from the filter top?

What version hand pump do you have?

I have the kind of pump that you unscrew and then plunger up/down.

[mikeyfev1]

OK, I have been reading the latest posts in this thread; I have 2 suggestions to use engine cranking to prime the lines--and I will try this (have to get back to where the car is located). But remember, this engine was running off the purge tank for about 5 minutes and then died from fuel starvation. At the start of the drive, I was seeing return fuel in the purge tank; at the end I did not. So if the engine couldn't keep itself primed do I really believe that the engine can prime itself? Just asking.

[tankowner]

Originally Posted by mikeyfev1

OK, so this means there is still no consensus on what I should do. I have a situation where I cannot prime my fuel system from a clear plastic bottle with diesel purge fluid in in. The intake hose (the hose to the primary (clear) filter) is in the fluid. Pumping for several minutes does not produce any suction. The primary fuel filter and the hose into the fluid is not clogged.

Any ideas?

You mention the primary, but not the secondary filter. When was the last time you changed your spin-on filter prior to this purge job? Even if fairly new, after five minutes of idling and a few miles of diving on straight diesel purge, you could have mucked up the secondary filter pretty good. What did the return purge look like while it was still flowing? If I were you, I would grab a new spin-on, fill it with clean diesel and replace. Then unhook the purge set up you have, reattach the fuel lines, and start cranking. Crank for 10 seconds at a time, then let your starter rest for a couple minutes before cranking again.

[tangofox007]

If your fuel pump quit working, the most probable cause is a sticking suction or delivery valve. Cleaning them might solve the problem. The delivery valve is located under the pump discharge nipple, the suction valve is on the underside of the pump behind a 19mm plug. Given the apparent "no suction" condition, I would start with the delivery valve.

[funola]

You may have a bad primer pump. Even if it is good, the white handle pumps spills a LOT of fuel. Try this: With the primer pump handle screwed down, crack open the fuel pressure relief valve (17 mm), then crank to bleed the air out till fuel comes out, tighen fuel pressure relief valve, then crack open an injector nut on one of the injectors 1/4 turn, crank till engine starts, then tighten cracked injector nut.

[mikeyfev1]

You may have a bad primer pump. Even if it is good, the white handle pumps spills a LOT of fuel. Try this: With the primer pump handle screwed down, crack open the fuel pressure relief valve (17 mm), then crank to bleed the air out till fuel comes out, tighen fuel pressure relief valve, then crack open an injector nut on one of the injectors 1/4 turn, crank till engine starts, then tighten cracked injector nut.

It sounds like you are responding to one of my earlier posts about an apparently non-functional primer pump. Thank you, but I have tried the "crank to prime the lines" experiment with no success.