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?

 

[Tx Jim]

1st thing blow air through fuel return line from inj pump to tank. It's also possible return line fitting is plugged.

 

[southwind26]

1st thing blow air through fuel return line from inj pump to tank. It's also possible return line fitting is plugged.

Blew the return line from inj pump out with air, it was clear, fitting was clear. Ran the tractor and fuel coming out is just a fast drip. Is this a sign the inj pump is going out?

 

[Tx Jim]

Can you get a gauge and test fuel pressure leaving lift pump?

 

[jd110]

No one has mentioned the possibility of a misfire. Does the engine seem to run as smooth at idle as it used to? Try loosening one line at a time at the fuel injectors and listen to how the engine sounds. If you loosen one that does not make a difference in how the engine runs, then that cylinder is misfiring. If so, then the problem could be a bad injector, a bent pushrod, broken rocker arm, etc.

 

[southwind26]

No one has mentioned the possibility of a misfire. Does the engine seem to run as smooth at idle as it used to? Try loosening one line at a time at the fuel injectors and listen to how the engine sounds. If you loosen one that does not make a difference in how the engine runs, then that cylinder is misfiring. If so, then the problem could be a bad injector, a bent pushrod, broken rocker arm, etc.

Thanks for the input jd110, the engine fires right up less than a quarter turn as always, runs smooth thru several rpm ranges. If I move the loader is will stall, if I just let the engine idle it will stall in about 2 mins.... If I loosen the injector lines one at a time, wouldn't it spray fuel everywhere or do I loosen just enough so a little fuel leaks and see if I can hear a difference?

 

[southwind26]

Can you get a gauge and test fuel pressure leaving lift pump?

I ordered a schrader valve and a gauge today, I should be able to test Tuesday

 

[jd110]

WHen you loosen the lines, some fuel will spray out, but not a large amount. It will be under high pressure, so be sure to keep your hands out of the way of the spraying fuel. Injection into the skin is very dangerous. After rereading your post stating that engine will also stall when idling after 2 minutes, that sounds more like return line plugged. DId you remove the return fitting that screws into the top of the pump? It should have a check ball in it. It is a pretty common problem for this check valve to be clogged and restrict return flow. The timing window is on the side of the pump. A small rectangular plate attached with two screws. Place a bucket under the pump and loosen the two timing window screws a cople of turns and then pry the window loose to break the seal. Start the tractor and let the fuel leak from the window. See if it still stalls when moving hydraulics or if it continues to run longer than 2 minutes.

 

[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

This picture shows the left side of the front hydro pump. I if I remove that 1/2 bolt from the top is this where I will put my new hydro gauge? I was worried that this was some type of a adjustment bolt for the pump. I removed the 1 1/4" plug from the other side of this bolt but those threads were very coarse threads not npt

 

[Tx Jim]

Before attempting to check hyd pressure be sure to check fuel return line fitting that attaches to inj pump for blockage. Port to check pressure is plug(parts key 26). The following spec's should get you an adapter.

 

[buickanddeere]

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

How does that make a difference once the starter is disengaged and the engine is running ?