B7100 - fuel system

[pacaron]

Have a B7100.
Fuel pump went out, replaced it with an electric. Works fine.
Couple of weeks later, tractor wouldn’t start (after a 24” snow):mad:.
It was blowing smoke and acting like it wanted to start, but never did.
Checked out the fuel system:
Fuel was flowing at the air bleed screw on the injector pump, loosened the fuel line connection on top of the (engine) injectors. Middle cylinder one wasn’t getting fuel. Disconnected the fuel line on the Injector pump to that cylinder. No fuel squirting out. Loosened the ‘delivery valve assy’ on Injector pump and suddenly it starts squirting. Tighten it back up… stops flowing. (You can do that with an elec. fuel pump).
Turned over the engine… same results.
So I loosened up the connection, put all the connections back together and tried to start it… Nothing, no smoke, nothing.. I checked the glow plugs with meter tester.. All working ok.
Now all cylinders have that problem… But even when the connections to the Injector pumps are loosen, fuel comes out the fuel lines.. But still won’t start. No smoke, etc.

The manual says when the fuel comes out the engine injectors, it comes out at nearly 2000psi. But fuel going into the engine injectors is only the 2.8psi pressure from the fuel pump. Is this right? How in the %$#(*^ does the engine injectors produce 2000psi? If the Engine Injector does not put out this kind of pressure.. then I know what my problem is... (Injector pump) As the fuel pressure isn't no where near that psi.

It may be because of the new rubber fuel line hoses (to and from the new Elect fuel pump) got some ‘particles from the hoses’ plug up the inner workings in the Injector pump (?).

I have not touched the Engine Injectors. I have cleaned the (few) parts under the Injector pump connections.. I have a (IT) shop Manual.

Any ideas? Disassemble the Injector pump and clean it? Or is this even possible for the avg. tractor owner...

[Service Dept Vic]

Pacaron,

Welcome to OTT! Sounds like you have a lot of questions here, let me try to point you in the general direction of a fix!

"So I loosened up the connection, put all the connections back together".......

Did you actually disassemble any of the 3 delivery valves on the injection pump, or just loosen them off and then re-tighten them?

A missing washer or a gasket reinstalled in the wrong place will change the injector timing and your Kubota will be very hard to start!

It's possible that some crap has entered the steel fuel delivery lines from changing the fuel pump, I'd remove them and blow them out to make sure.

Doubtful that your problem is located in the injectors, but they are easy to disassemble and clean, they need a spray pattern/pressure test to determine their efficiency. Any diesel repair shop can check and test them for you, but since no fuel seems to be getting to them, I don't think your issue resides there.

The job of the fuel lift pump is to deliver fuel to the injection pump at low pressure. The injection pump has 3 pistons inside it like a pressure washer pump at the car wash. Low pressure in, high pressure out. The fuel in your Kubota is compressed and delivered under extreme pressure to the injector nozzle which is designed to "crack" open at a specific pressure, around 2000PSI.

Since the fuel " comes back" when the delivery valve is loosend off and stops flowing when it's tightened would indicate to me that the problem is located in the injection pump/delivery valve areaand would probably have more to do with a misplaced shim or gasket rather than a mechanical breakdown.

144

[pacaron]

Thanks Farmm.
Yes I did take two of them out... and replaced the parts in the same order...
The parts #250 (small collared metal part with hole in the middle) & 260 (shim) + small plunger? (that goes into the hole on #250) and the spring on top of #250.
Plunger fits inside.. Was taken out.. inspected and replaced in same order.
I didn't go any 'deeper' than that.
Perhaps I should.. I've read ain't no picnic if you take off the 4 bolts on the Injector pump and start looking around. But is it safe to take out the Plunger pump (#020) and related parts (See the attached)... Clean and put them back together (carefully)?
Would that help.
Ironically the multiple part diagrams that I have (including yours), none match exactly what I inspected.
I drew a pic (also attached) up to show what I found. On top is the spring followed by the fuel line nut.
Oh, BTW the collared piece just sits in the middle. The spring centers the parts in the plunger pump.

Thanks for your help. Ron