M7040 fuel system bleeding

[TruckinFool]

What is the proper process to bleed the fuel system? I was watching a video in another language and I noticed them mess with a screw next to the fuel shut off. What is this?

My motor seems to have a bit of a knock to it that sounds like regular diesel knock but sometimes its louder than others. I was thinking it might be air in the injector pump? Tractor is new to me so not sure what its "supposed" to sound like. Runs fine, good power etc.

When I clean the water separator filter I turn the fuel "off", drop the bowl, clean & reinstall. Turn the fuel "on" and pump it until it feels firm. Starts right up. A while ago I did notice bubbles in the bowl while the tractor was running, not sure if thats normal?

Thanks for the help. Dont feel like dragging it to dealer for no reason.

 

[Tx Jim]

The way you described cleaning water separater filter is the same way I clean mine. Different engine operating temps can make engine sound different. I think you are worrying about something unnecessarily. If the engine sound really bothers you independently loosen then tighten each inj line nut at injector while engine is running. This will allow any trapped air to escape.

CAUTION: keep fingers away from diesel under pressure.

 

[The Fred]

The fuel valve you speak of simply returns more fuel to the tank thus purging the lines of any air. Simply open the valve and let the machine run and I am sure high idle will not hurt anything. One can actually pull the line off at the tank and see the fuel coming through.

Fred

 

[Tx Jim]

The fuel valve you speak of simply returns more fuel to the tank thus purging the lines of any air.
Fred

Fred
If the fuel shut off at water seperater is what TruckinFool is referring to it has nothing to do with fuel return line. The water seperator housing has only 2 hose barbs,one for supply hose from tank and the other leading to inj pump. Yes I agree one can remove any of the fuel return lines while engine is running. The only way to completely purge air once it's gotten past inj pump is by loosening inj lines while engine is running.

 

[TruckinFool]

No idea what the galvanized screw is to the right of the shut off valve? It's maybe 10mm and a philips head.

 

[The Fred]

Fred
If the fuel shut off at water seperater is what TruckinFool is referring to it has nothing to do with fuel return line. The water seperator housing has only 2 hose barbs,one for supply hose from tank and the other leading to inj pump. Yes I agree one can remove any of the fuel return lines while engine is running. The only way to completely purge air once it's gotten past inj pump is by loosening inj lines while engine is running.

Yes I have the wrong valve sorry. I am talking about the one that is painted on the side of the injection pump. It sounds like you could have an air leak into the fuel line. Not that familiar with the 7040 fuel line setup. How about a picture?

Fred

 

[Tx Jim]

Fred
Here is a schematic. I think M7040 doesn't have a valve similar to what you refer to on the inj pump.

 

[TruckinFool]

Here's a picture. Its actually above the valve. (sorry was working from memory)

Can not find the video again. I believe they shut it after the tractor was running so maybe the pressurized fuel is supposed to bleed the air from that point?

I came across the video trying to find one of a m7040 at idle. It surely doesn't sound like a skid steer etc where its just a smooth running sound. The engine itself is smooth but its got a pronounced cackle like an old tractor. I cant seem to hear it on youtube video's.

Another thing I noticed is that when its cold I HAVE to start it at half throttle. Some guys on here seem to start fine at idle. If I do this it will most likely start but its a gurgling mess for about 30 seconds before it can build rpm. Below 20f I'm not sure it would start at idle.

(I've replaced the fuel filter already and sorry the picture is sideways?)

 

[Tx Jim]

As I've previously stated "don't you have something more important to worry about"? My M7040 has a different sound when I crank it in below freezing temps then in about 30 seconds the engine levels out. I'll worry when engine running won't level out or IT DIES!!!!!!!!!!

 

[TruckinFool]

Haha I suppose. It makes the knock warm, cold etc. I just mentioned the cold start because if it was different than yours I'd look into fueling issues.

 

[Tx Jim]

As I previously suggested loosen then tighten each inj line while engine is running to determine if air in inj line is a problem

 

[TruckinFool]

As I previously suggested loosen then tighten each inj line while engine is running to determine if air in inj line is a problem

Sorry, I didn't see it. Are you sure this is safe? What are the rail pressures? I've been told you can kill yourself doing this on trucks?

 

[Tx Jim]

M7040 isn't an ultra high pressure common rail system. As I previously stated CAUTION: keep your FINGERS from coming in contact with spraying diesel fuel but I've survived bleeding air out of inj lines many times. Final line is BE CAREFUL!!!!!!!!!!

 

[TruckinFool]

10-4 Thank you

 

[whis]

its a bleed screw, loosen and pump primer till fuel comes out

 

[Tx Jim]

its a bleed screw, loosen and pump primer till fuel comes out

whis
I agree with screw OP inquired about being a bleed screw BUT if his engine is truly running bad loosening that bleed screw won't correct the problem.

 

[TruckinFool]

So if you remove that screw you loose suction from the tank. Not sure what its purpose is but its not to bleed the system. I think you can use it to drain the bowl back to the tank before removal? Anyway, after messing with it and priming, I no longer have air bubbles in the top of the bowl while running. Noise never changed but I think all is good.

 

[whis]

its to bleed water filter

 

[TruckinFool]

But its the suction side?

 

[Tx Jim]

But its the suction side?

Are you concerned that water filter is between fuel tank & lift pump? My M7040 is one of the easiest diesel engines I've ever owned/worked on to bleed the air out of the fuel system and get it to run.