# John Deere 820 starting/running problem



## Savannahman (Jan 29, 2013)

The guy I work for(restoring things) has a John Deere 820 3 cylinder diesel. It hasn't had a lot of just plain good sense maintenance. It does get the oil changed on regular basis. The problem is it started running, shutting off. Finally it died complete. I said it's probably the fuel filters because you could tell they hadn't been changed in years.Well the filters got changed, but now it will crank, run for about 30 - 45 seconds and shut down. Wait a minute or so, cranks right back up but shuts down again. The guy that changed the filters said it had fuel pressure(not checked with gauge) coming out of the lift pump( which I don't think is the right pump, no primer lever), but just trickled out of the injector pump. I told him that I didn't think a diesel would run at all if injector pump wasn't putting out or not enough pressure. The filters had a lot of rust in them. Now the Question, is it possible for the lift pump to be pumping, but not putting out enough volume or pressure? I know it hasn't been changed in years also. Any suggestions on how to fix it would help me a lot because I need to use it from time to time. 

Thanks, Savannahman ( Ray)


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## thepumpguysc (Jan 25, 2015)

The inj. pump, if its a Roosa Master, only need about 1-3 psi to run.. So basically, they'll run on gravity pressure.. The lift pump is only a helper pump to get the fuel from the tank to the inj. pump, the inj. pump has its own transfer pump that draws the fuel BUT it has to be unrestricted.. IF your lift pump is bad, its stopping the inj. pump from drawing the fuel..
Do you know what inj. pump is on it? The pump generally has a name tag on it..
Is there a side cover on the pump w/ 2 flat head screws? Loosen the screws and allow the fuel to run out alittle, & try to start it.. if it starts & runs, you have internal pump problems, flex ring has broken up.. This diagnostic is only for a Roosa Master rotary pump. 
Good luck and contact me if you need to.. TPG


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