JD 750 not getting fuel after changing fuel filter

[txjay]

Hi yall,

I tried looking for an old thread on this, but couldn't find one specific to my tractor and problem. Anyway, I would appreciate any knowledge and help anyone might be able to offer. I have done plenty reading on how to bleed the fuel lines on other tractors, but I just cant seem to be able to translate or apply those steps into how my tractor is setup and the location of the parts are different.


I just changed the fuel filter on my JD 750 (round 1983). It ran good before, but wont even try to fire up now. right after I changed the filter, it ran fine for a few minutes until it used up all the fuel in the lines.
From what I understand, this tractor is suppose to be "self bleeding" but a lot of other models have a manual priming pump.
I have so far spent about 4 hours trying to trouble shoot this, heres what I have done so far.

1. Confirmed tank has diesel/shutoff valve was open, although tank is low (It is above where the fuel line comes into the bottom of the tank, but maybe only has 1/8 of a tank) Probably a dumb question, but...If there was more fuel (weight) would that mean more pressure to help gravity feed fuel through the system? I plan on stopping by after work today and getting a few gallons.

2. Removed fuel bowl and filled with diesel. While it was off I opened the valve and made sure there was a good flow of diesel coming out.
When I put the bowl back on, I removed the line coming out of the fuel injection pump to the filter from the filter housing. If I lowered it below the fuel filter bowl, fuel flows though, when I hold it above it stops(makes sense because where that line ends up going into the fuel injector pump is located higher up than the fuel filter bowl)--This also appears to be the last point that is receiving fuel.

3. This is where I start to get confused on which screw/part is which. I unscrewed what I believe is a air release/bleeder screw right next to where the line from filter goes (This is the labeled "E" on the pictures i attached) into the fuel injection(the the injection side of the above mentioned line), Nothing comes out, I tried cranking the engine over for a few minutes, still nothing came out. Is this a bleed hole or am I just wasting my time messin with it?

Also, could someone help me identify the reservoir above the cylinders (its letter D in one of the pictures I attached). One end im not sure where it is coming from (not able to look right now, but can find out) the other end goes back into the tank (return?) and then there is a bigger rubber hose that runs down to the air intake near the block. I originally though it was some sort of primer, but you cant really squeeze or pump it. It is full right below where the hoses on top go in and come out.Could this be the problem? Should it be all the way full past the hoses to create a suction/siphon in order draw fuel up?

I appreciate any help I can get, I am just starting to learn. hopefully someday I will be knowledgeable enough to contribute back to the forum.
Jay

 

[arrow]

Nope. Not self bleeding. Had to bleed mine all the time. You are correct. Those Phillips are all the bleed screws. When I bled all of these after running out of fuel, the tractor would eventually start up. You have air trapped someplace still. I can only tell you how I did mine. Empty the fuel bowl and crank the engine. Bleed the air at the two fuel bowl screws going from the left to right. This should fill the fuel bowl. Next, bleed the air at the injector site until you have diesel coming out. This should cure your problem. Let the lines fill naturally.

 

[Rock knocker]

On a 950, A&B accomplish the same thing.

Never messed with C. I think it is the filter assembly to block bolt.

D shouldn't play a part in this task.

E looks to be the gravity supplied inlet to the fuel pump. There should be fuel there if it is in fact the feed to the pump. It shouldn't be a difficult task to follow the hose from the filter to the pump.

I normally drain at A or B, the jump to the high pressure tubing at the injectors. If you can't get all three, don't sweat it, two is sufficient. But confirm identification of E and fuel there first

 

[Rock knocker]

Also, make sure the throttle lever is in "Run"

 

[txjay]

Thanks for suggestions yall, stopping to get more diesel on the way home and then ill give er another go. How far on the throttle,? Ive heard some people say 3/4 and some say full throttle...full throttle makes more sense to be but...

 

[Rock knocker]

1/2 to 3/4 should be fine

 

[txjay]

Thanks Arrow and Rock Knocker for your help. I put about 2 gallons more diesel in er last night and re-bled air from screw A and then screw B then crank it over for about 20 seconds before she fired up.