JD 401 hydraulic problem

[southwind26]

Hey everyone, I need some help. Have a 1971 JD 401 and when I use the loader the motor wants to stall. I parked the tractor about a month or so ago and when I parked her she was running fine. The motor fired right up on a quarter turn just like always when I started her this week. I raised the rpm to lift the loader and the motor boggs down even when I lower the loader. I changed the fuel filter didn't see any thing unusual (was hoping to see water) changed both hydro filters and oil, clean screen, it had some crap on it but I haven't cleaned it in 20 yrs. Not sure what to check next.......

 

[60lp]

Hey I've got a 300b Deere backhoe it has the electric wire that goes to hydraulic pump it makes the releases the pump pressure that might could be your problem

 

[southwind26]

Thanks 60Ip, I'll go and check that right now

 

[Tx Jim]

Hey I've got a 300b Deere backhoe it has the electric wire that goes to hydraulic pump it makes the releases the pump pressure that might could be your problem

Electric destroking valve isn't the problem. I'll recommend checking stand-by pressure which should be 2350 psi. Have you checked for good fuel flow from the tank. Also check too be sure fuel return line is unplugged from inj pump to tank.

 

[60lp]

Tx Jim i had forgot what you mentioned I just had that problem my return line that goes to the tank was stopped up it was on my 301 tractor boy is my memory felling or what lol

 

[southwind26]

Tx Jim i had forgot what you mentioned I just had that problem my return line that goes to the tank was stopped up it was on my 301 tractor boy is my memory felling or what lol

Tx Jim was right I have no wire coming off the front pump. I did check the fuel flow to the lift pump but didn't check the return line to the tank. What is in involved in checking the stand by pressure, I have not done. Also laying in bed last night I was thinking I only took out 5 gal of hydro oil when I clean the screen. Would the hydro system bog down the motor if it was starving for oil?

 

[Tx Jim]

To check stand-by pressure one needs a 3000-5000 # gauge with the correct hyd fitting to attach to hyd pressure port. Here's the spec's for the pump plug(parts key 5) if your tractor has the smaller pump
Specification
Weight: 0.18 LBS 0.08 Kg
Thread Size 0.750 IN
TPI (Threads Per Inch) 16
Thread Length 0.438 IN
Length 0.750 IN
Diameter 0.465 IN
Hex Size 0.875 IN

 

[southwind26]

To check stand-by pressure one needs a 3000-5000 # gauge with the correct hyd fitting to attach to hyd pressure port. Here's the spec's for the pump plug(parts key 5) if your tractor has the smaller pump
Specification
Weight: 0.18 LBS 0.08 Kg
Thread Size 0.750 IN
TPI (Threads Per Inch) 16
Thread Length 0.438 IN
Length 0.750 IN
Diameter 0.465 IN
Hex Size 0.875 IN

Is there a place on line you can recommend where I can get the gauge?

 

[Tx Jim]

HERE YOU GO

 

[southwind26]

Hey everyone, I need some help. Have a 1971 JD 401 and when I use the loader the motor wants to stall. I parked the tractor about a month or so ago and when I parked her she was running fine. The motor fired right up on a quarter turn just like always when I started her this week. I raised the rpm to lift the loader and the motor boggs down even when I lower the loader. I changed the fuel filter didn't see any thing unusual (was hoping to see water) changed both hydro filters and oil, clean screen, it had some crap on it but I haven't cleaned it in 20 yrs. Not sure what to check next.......

I think I'm getting close, I checked the returned fuel line from injectors to fuel tank as Tx Jim recommended and have no fuel returning to tank. I put a piece of clear fuel line on the line between the tank and lift pump and another piece of clear between the lift pump and fuel filter. This way I could see fuel flowing into the filter. How do I check the fuel between the filter and injection pump and the how do I test the injection pump or I'm I missing something in between?