D750B Tries to start but won't catch

[Sgtwal]

I have a D750 B in my tractor. I had to re-assemble the engine as the head and other minor parts were off from where the owner changed engines and never finished the job.
The engine cranks good and I get vapor from the exhaust. It will try to fire if I get the throttle right but it stops fireing when I let off the starter.
Any suggestions?

 

[D2Cat]

Sgt, sounds like you're real close to hearing the sweet noise of your engine running. I'd suggest you go through the process of bleeding the the air out of her again. You may be close enough to a start you could simply loosen the nuts at the injectors and turn the starter over for 15-20 second intervals a few times. When you see fuel dribbling out of each line, tighten them up.

This process is easier on the starter if you have the compression release pulled out.

 

[North Idaho Wolfman]

I second D2Cat's suggestion to bleed the injector lines.

 

[Tooljunkie]

Any chance i could be something like valve adjustment?
Set too tight, and not sealing? Unlikely, just askin is all.

 

[Sgtwal]

I've bled the system several times and get air every time. I'll try again.
It sat for a couple years before I got it and I replaced most lines and clamps due to dry rot cracking.
I'll let you know if that helps. When I replaced the head I set the valves within the range in the book but there is always the chance they aren't seating after such a long set.

 

[North Idaho Wolfman]

If you just keep getting air and no fuel you have an injector pump problem.

 

[Sgtwal]

If you just keep getting air and no fuel you have an injector pump problem.

What I meant was that I get air from the lines each time I bleed them. I can bleed the lines to get fuel flowing as far as the injectors and the next time I try I get more air all through the system.
I seem to be pulling air from somewhere.

 

[D2Cat]

Did you replace the small return lines off the injectors?

 

[Blkvoodoo]

Prime the injection pump, bleed the injectors, then remove the injector lines from the injectors and crank, see what happens.

I had a couple bad injectors in a John Deere engine ( in a LULL ) that engine compression was pushing back thru the injectors ( 3 of the 4 ), I bled multiple times, my boss bled, multiple times, pulled injectors out and connected to lines, and crank to check spray pattern ( field job at a construction site, not real pretty but effective ) put one injector back in and snugged it down, cranked again testing another, fuel came shooting out of the injector that had been installed ( but not connected to injector line ) took all 4 injectors to diesel shop, they tested and all failed, basically the poppets had failed and the engine compression was pushing back into the fuel system.

Something to check.

 

[North Idaho Wolfman]

What I meant was that I get air from the lines each time I bleed them. I can bleed the lines to get fuel flowing as far as the injectors and the next time I try I get more air all through the system.
I seem to be pulling air from somewhere.

Could be the injection pump, lift pump, fuel filter, or any line that feeds the pump.