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51farmallm

806 diesel loses power

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Hello  I have a problem with 806 diesel that runs good at full throttle then dies  after 10 min or so has little to no power  smokes gray smoke.   fluids all look good  changed filters still does same also checked fuel return line it is open.  After is sits for a while will start right back up but does same thing .  Any advice is appreciated .   

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is your fuel tank vent open sounds like it creates a vacuum and starves it for fuel

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Check the fuel return fitting on top of the injection pump for plugging in the check valve. Or, easier, just take the little timing cover off the side and look for coffee ground like pieces of plastic.  There is a plastic elastic dampener on the governor weight retainer that disintegrates and plugs return.  If so, pump will need to be repaired.  

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Our 826 did the same thing, found the fuel return check valve at the bottom of the tank was the culprit. I took the return line and put into a fuel can and she ran perfect, hooked it back up and problem came right back. Remedied the sticking check valve and issue resolved. Good luck.

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That is a classic symptom of a deteriorating elastic dampener ring.    Happened to my 806 when I was trying to bale hay....change filters, etc, get halfway down the field and DIE.....all the guys on the rack standing around offering suggestions!

Sounds like you already checked for fuel flow and return blockage, so pretty sure its the pump.

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Slightly loosen side cover on pump for timing and see if it stays running, it will leak a little fuel but if it stays running then pump needs work.

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I assume this has a Roosa Master pump on it?

If not, you may have other issues.

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With he engine running and all return fittings removed from the top of the pump, it should run and dribble fuel out the top of the pump.

Then start putting fittings back in unit it stops or all the return lines are hooked back up again.

The very top fitting in the pump has a check ball in it that looks like glass. May be plastic.

If using air to blow that clean, you need to use a needle, etc to move that ball off it's seat to get air to go through the fitting one way.

Fuel will flow one way, from the pump to the tank unless that fitting is plugged. The ball stops fuel from flowing back into the pump from the return.

That fitting will be packed full of like a very fine black sand.

That was originally a clear or tan piece of plastic that held the governor weight retainer together. 

The two pieces of the governor weight retainer are now floating around unattached in the pump.The governor does still work and is turning.

When replaced, you can use a solid weight retainer that stops this from ever happening again.

They say it can effect the governor but I have never seen it.

Always remember, a Roosa Master must allow return fuel out the top of the pump against zero pressure.

Any pressure builds and it will slow the engine until it quits.

The remains of the elastacast ring that holds the governor weight retainer together has disintegrated, plugged the return somewhere and stopped the engine.

This is the best place to start.

 

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