roosa master fuel pump

I just bought a IH 1256 (my first) was running good for about an hour after fuel filters were changed, then she puked. After an hour or so trying to get it running the best I could do was run 15-45 seconds, then I opened the "1/2" head bolt on the side of the fuel pump and it stays running when I tighten it she shuts down. Any Ideas ??? I have good fuel flow to the pump and the system seems to be clean. Thanks for any help!

(quoted from post at 16:05:30 06/23/11) I just bought a IH 1256 (my first) was running good for about an hour after fuel filters were changed, then she puked. After an hour or so trying to get it running the best I could do was run 15-45 seconds, then I opened the "1/2" head bolt on the side of the fuel pump and it stays running when I tighten it she shuts down. Any Ideas ??? I have good fuel flow to the pump and the system seems to be clean. Thanks for any help!

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Common problem with the roosa pump, the restrictor fitting on the pump cover where the return fitting connects is plugged with pieces of the coupling ring that drives the governor cage. They deteriorate over time. Unless you are fairly mechanical and pay very close to parts placement on disassembly it will be to your benefit to have a diesel pump rebuilder do it. The bleeder screw being closed is allowing the internal pump pressure to build to a point that the pump quits delivering fuel to the injectors. When the screw is cracked open the pressure is released and it will run.
mEl

You may want to check the return lines for a obstruction.

You may also check the line from the tank for pinholes. they won't drip fuel but will stay damp ,if so pump will start to suck air into the system, also check the vent in the tank. Bought a 1456 from a sale and after two months of chasing this gremlin[same problem you have] we cleaned the vent and replaced fuel supply line. Problem solved,hope this helps with the problem.

I'm not really sure what 1/2" headed bolt you're talking about, unless it's on the round part of the body near the rear,that's one of the screws securing the hydraulic head. At any rate, it sounds like you're relieving housing pressure when you loosen the bolt. If this is the case, the return elbow in the pump cover may be plugged. It may be an orifice or a spring-and-ball affair, but the function is the same, to maintain 6-12 PSI in the housing. If the housing pressure is too high, the cam ring will become fully retarded to the point where it won't run. Another possibility could be the regulator sleeve or plunger within the charge pump jammed (on the rear of the injector pump). This could also cause high housing pressure. It's possible you disturbed something when you changed the filters, since pump trouble cropped up only an hour later. However, for that to be true, the teeny inlet screen ahead of the pump would have to be damaged or missing. I would replace any original rubber hoses in the fuel system. The fix for the return elbow is obvious, but if you want to go after the regulator, you will have to remove the pump from the tractor; this must be done in a clean place. Get yourself a cutaway view or an exploded diagram of your pump (I&T is good) and go to it. when you get down to the regulator adjusting screw, measure it's depth or count the turns to remove it. Good luck! Fritz.

The reason a RoosaMaster pump quits working when the fuel return is blocked is the the high pressure side of the pump depends on a difference between supply pressure and case pressure to move the two pistons out to receive a fresh fuel charge. If the case pressure and supply pressure are equal the pistons can't move so no fuel will be available to go to the injectors.

"I'm not really sure what 1/2" headed bolt you're talking about, unless it's on the round part of the body near the rear, that's one of the screws securing the hydraulic head."

Yep, I think you've got that one figured out... he loosened a bolt holding critical parts of the IP together!

It's hard to IMAGINE the STUPID things people do... like loosening a critical bolt to see if that would make the engine run... (I guess it makes FAR more sense than checking the return line/fitting/housing pressure regulating valve, though!)

Like a hero of mine once said... "You can't make ANYTHING idiot proof 'cause idiots are CLEVER"!

Proven, once again, here!

(quoted from post at 02:06:33 06/24/11) "I'm not really sure what 1/2" headed bolt you're talking about, unless it's on the round part of the body near the rear, that's one of the screws securing the hydraulic head."

Yep, I think you've got that one figured out... he loosened a bolt holding critical parts of the IP together!

It's hard to IMAGINE the STUPID things people do... like loosening a critical bolt to see if that would make the engine run... (I guess it makes FAR more sense than checking the return line/fitting/housing pressure regulating valve, though!)

Like a hero of mine once said... "You can't make ANYTHING idiot proof 'cause idiots are CLEVER"!

Proven, once again, here!

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Yeah Bob, I was not thinking straight in my response. The Roosa has no bleeder screws and I did not pick up on that, the CAV's have that. Anyway, the principle is the same. Plugged return, probably at the restrictor fitting. mEl

He opened the bleeder screw. No harm done. But I agree the problem will be in the return system. Check valve could be clogged or return line plugged up.

(quoted from post at 11:37:12 06/24/11) He opened the bleeder screw. No harm done.

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No 1/2" or any other type bleeder screw on a Roosamaster inj pump that I'm aware of.

I have been bleeding them for thirty years.

I've bleed them also but I have not seen a bleeder screw. What model tractor or inj pump are you referring to? Can you please post the part # of this bleeder screw??
Thanks