Purge Air from Fuel Line - General Diesel Engine Help

[funwithfuel]

Leaks on suction side are a challenge. Since they pull air rather than leak fuel. Try priming her up from an alternate source like a 5 gallon jug of fuel. That way you can see if your fuel level diminishes while priming

 

[skobydog]

Seems like it's not pumping much fuel. Is this correct?

 

[funwithfuel]

That's pretty weak, looks like check valve might be hung open. Are you getting full stroke on the pump lever, or do you have a long dead spot followed by a little resistance?

 

[skobydog]

That's pretty weak, looks like check valve might be hung open. Are you getting full stroke on the pump lever, or do you have a long dead spot followed by a little resistance?

Here's another video. I have the tube hooked to the inlet "stub" where the filter sits on.

That's about as full swing with the pump as I can get. About 1/2 to 3/4 of the way I feel a little resistance like it's starting to pump. It doesn't seem like much but I don't know.

 

[Delmer]

That second video doesn't look too bad?

How the pump works isn't intuitive. The lever and cam lobe pulls down the diaphragm against a spring, which pushes the fuel out. If the outlet is blocked the fuel will maintain pressure by the spring and the diaphragm won't return and there won't be pressure on the arm, just the little external return spring. (that diaphragm wouldn't last an hour at full stroke at engine speed). If you get much more pressure than the main spring, then you might be pulling against a blocked suction side. Disconnect the inlet and see if it gets easier to go the whole stroke. Then find your blockage on the suction side (reconnect, then go one step at a time checking for vacuum with the pump).

Or hook both sides of the pump up to a can of fuel and see how it pumps when you block the inlet, outlet, etc.

 

[skobydog]

I decided I'd try putting it back together. When I loosened the injectors some fuel came out but it wasn't spraying out like it was under high pressure.

I did get it to start for about 1.5 secs on two occasions but that was it. I'm not sure if I flooded it, it's the weather, or something else but it won't start. I'm charging the battery now and may try again tomorrow.

By looking at the smoke from the exhaust it looks like it's getting at least some fuel. Seems it to me but I don't know.

 

[thepumpguysc]

MAKE SURE the throttle is wide open when trying to start it or bleed it..
Do you have an air compressor?? Loosen the lines at strategic points, before the filter, at the pump inlet, ect. & pressurize the system..

 

[funwithfuel]

^^^^^^^
What he said , except, regulate air to no more than 5-6 psi. Any more and you may wind up with unintended consequences

 

[funwithfuel]

Back to basics though. If and when you pressurize the fuel system start at the lift pump inlet, you should have steady flow. If you do not, one of 3 things. Insufficient fuel or damaged stand pipe or obstruction in supply. If this occurs, run off alternate source. It's hard enough to diag no start but to do it with unknown source really causes grief.

 

[Birken Vogt]

Or just dump fuel into the tank 5 gallons a day whenever you get home, until it is nearly full, you know it ran fine before so no reason it should change now.

 

[Delmer]

About 1/2 to 3/4 of the way I feel a little resistance like it's starting to pump.

That's a clue that your suction is plugged. Which is why it stalled after starting. Look for another problem all you want, or find the problem you have. If it's sucking air, then it would be blowing air out with the little bits of fuel and not having added resistance 1/2 -3/4 of the way on the pump stroke.

 

[skobydog]

Can I bypass the lift pump using gravity to feed the injector pump? I could put a fuel source above the injector pump and siphon it into the fuel filter outlet port so it feeds into the injector pump.

Would this work or do I need pressure at the inlet port of the injector pump?

 

[Birken Vogt]

That should work, bearing in mind that the pump returns quite a bit to the tank so once it is running, it will pump out the gravity tank pretty quick.

Also I would not under any circumstances run unfiltered fuel into an injection pump. Maybe just gravity it into the lift pump inlet.

 

[skobydog]

Maybe just gravity it into the lift pump inlet.

This seems like the easiest thing to do next.

I could try pressurizing the system but I don't have the correct fittings. Anyone see why gravity feed to the injector pump would not work?

I did try to bleed again at the injector inlet and then at the injectors earlier today. I'm not getting much fuel out of the injector lines. I'm hoping it's not the injector pump.

 

[Delmer]

Are you philosophically opposed to finding the problem for some reason? This seems simple, find the problem, fix the problem, done. I don't see what you get by using a temporary tank in this situation. If it starts and runs until the temporary tank runs out, then you know you have a blocked fuel supply, which you already know. Why not find the blockage and fix it? You can use the priming pump to find the blockage, or pressurize the tank and see where you get good flow and where you don't. A piece of inner tube with the valve stem attached, held over the fuel filler opening is an easy way to get a pound or two of air pressure in a tank. Or if there's an overflow/vent tube, hook a clean tube to it and blow by mouth.

 

[skobydog]

Are you philosophically opposed to finding the problem for some reason? This seems simple, find the problem, fix the problem, done. I don't see what you get by using a temporary tank in this situation. If it starts and runs until the temporary tank runs out, then you know you have a blocked fuel supply, which you already know. Why not find the blockage and fix it? You can use the priming pump to find the blockage, or pressurize the tank and see where you get good flow and where you don't. A piece of inner tube with the valve stem attached, held over the fuel filler opening is an easy way to get a pound or two of air pressure in a tank. Or if there's an overflow/vent tube, hook a clean tube to it and blow by mouth.

The reason I wanted to try the temporary fuel tank was to see if the injector pump is working. I guess I want to hear the engine run.

I'll try pressurizing the system and see if that works. I have small air pump and will need to pick up a schrader valve. It will be a couple days because of work.

 

[Birken Vogt]

If you have a regular air compressor a helper with a rag shoved on the gas filler and a blowing air hose in there as well will do it, just watch the line to the IP and tighten it on when fuel shoots out, then it should start right up same as it was before it ran out.

 

[skobydog]

I got it fixed. I temporarily changed out all my rubber fuel lines to clear pvc so I could see what was going on. I think the water/fuel separator was leaking just enough to not allow me to draw fuel up.

After I got it put back together I ran it with the pvc line temporarily to make sure air wasn't getting into the line. I've changed it back since this video.

I learned a lot from this and everyone here. Thanks everyone for the help.

 

[skobydog]

Just adding this video that I realized I had taken.

I was able to start the machine using siphon/gravity from a 5 gallon tank. Once I lowered the tank the machine kept running. The clear vinyl/pvc tubing allowed me to see what was happening. In the video you can see a significant air leak coming from the water/air separator. The rubber grommet on the bottom the water/air separator had a very small leak which I didn't see what the machine was not running.

Thanks again for everyone's help.