Fuel line Bleeding

Nokosie · Nov 2, 2022

I am have some real issues with my tractor not starting. I replaced the fuel filter and can't seem to get the air out of the system. I have tried to follow all instructions but it's just not working.
I think one of my problems may be that my fuel lift hand pump doesn't work. (It doesn't seem to work) so I'm not sure how to bleed the line. Ive been loosening bleed screws amd crankimg the engine but thats not working. Still can't seem to get the air out.
I have bled the system before and was able to get it running again but not this time, so I'm kind of stumped.

One thing to take not of: it was having issues before this. It would start and then shut down after about 10 seconds. That's why I replaced the fuel filter. So that may have not been the problem but I am pretty sure there is still air in the line.
Thanks

JWR · Nov 2, 2022

Sounds to me like you had a significant issue before air in the lines. I will mention a few possibilities I know of:

1) Depending on the age of your Massey old deteriorated fuel lines develop air leaks and can get air in them even when there are no obvious leaks. For example the line feeding your injection pump can be sucking air as well as fuel which I think could cause your issues. Neoprene lines are cheap and it might be well to replace as many as you can get to if this is an older machine. So I backtrack some and say MAYBE air in the lines was your original problem too ??
2) I suggest loosening your injector lines one by one and cranking the engine. That will do two things -- first it will tell you if you are getting high pressure fuel to each injector or not AND will inherently prime all those lines by pushing air bubbles out of them if it is in there. This should also take place of any absence of function of your hand bleeding pump.
3) That prior issue of starting and then quitting after 10 seconds or so is pretty typical of fuel starvation. I'm thinking on the low pressure fuel area before the injection pump. The reason I say that is that while sitting or in repeated attempts to start you get SOME fuel to the high pressure pump which is enough to run for a few seconds but then it dies for lack of replacement fuel getting to the injection pump. Does this MF have an electric low pressure pump pulling fuel from the tank and feeding the injection pump? If so that low pressure pump could be bad.
4) Of course there are all sorts of possible fuel system maladies that can cause problems including plugged outlet from the tank, a plugged vent in the tank cap (easily checked by just going without the cap for a few trials), etc. There have been many threads on these diseases and you can do a thread search for those if that seems like a possible problem. You could hang the equivalent of a hospital IV bag filled with fuel and let that feed the injection pump. If it still has your same problems then that clears guilt from all the stuff preceding the injection pump. Of course if it runs OK from the IV bag then you know the problem is prior to the injection pump. Narrows it down.

I think if you wade through the things I mentioned above it will isolate your problem so you can fix it.
Let us know how it goes.

Dmacleo · Nov 3, 2022

probably would get more specific help if you mentioned year and model of tractor......

MTGreen · Nov 3, 2022

Couple of thoughts in addition to what's been mentioned in the post above: First is make very sure that you are not getting air into your fuel line between tank and filter -cracked hoses, loose fittings, etc. Second is those hand pumps go bad over time with rubber deterioration/cracking/shrinking and some can be reassembled incorrectly. I had one looked just fine inside and out but wasn't sealing/pumping because the diaphragm had shrunk slightly and wasn't making a good seal.

Oh and one other thing is you could consider installing a one way check valve in the tubing between tank and filter if you keep losing the prime

PJRAM · Nov 4, 2022

Nokosie said:
I am have some real issues with my tractor not starting. I replaced the fuel filter and can't seem to get the air out of the system. I have tried to follow all instructions but it's just not working.
I think one of my problems may be that my fuel lift hand pump doesn't work. (It doesn't seem to work) so I'm not sure how to bleed the line. Ive been loosening bleed screws amd crankimg the engine but thats not working. Still can't seem to get the air out.
I have bled the system before and was able to get it running again but not this time, so I'm kind of stumped.

One thing to take not of: it was having issues before this. It would start and then shut down after about 10 seconds. That's why I replaced the fuel filter. So that may have not been the problem but I am pretty sure there is still air in the line.
Thanks

Not sure if this will help, but worth a try I guess.