863 loss power/replaced fuel filter/back pressure in return lines?

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Jimmy313

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Sep 11, 2016
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Hello, I own a 1999 863 with the 73 hp duetz motor. Cleaning up around property and noticed when ever I put a load on machine. The machine would lose power and motor would start fluttering. Remove the load and it would go back to running smooth. So I started by changing fuel filter. After I changed the filter. I started machine up and let it run for bit to make sure there were no issues. After bout 5 min I noticed fuel dripping from what seemed like all the braided return lines. I bought and installed a new return line kit earlier this year. So all the lines are in great shape. So I know those are fine. It seems like there is a back pressure causing the fuel to leak out of the return lines. Any ideas what is causing this? Maybe a bad injector? If it is an injector issue. Is that what could have been causing the loss of power issue? I didn't look to see if fuel was leaking before I replaced the fuel filter. I'm just hoping I don't have to break into the fuel system of this machine as I hear it can be some what of a nightmare. If it is an injector. Is it as simple as replacing injector bleeding fuel line and being done? Or is there more to it than that? I'd appreciate any advice or input. Thanks
 

Tazza

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Dec 7, 2004
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16,829
The tap off lines shouldn't leak, there is almost no pressure in them.
Changing injectors isn't that hard, pull the old and install the new.
You mention power loss, i'm wondering if your turbo is running right. If you remove the inlet hose to the turbo, see if you can spin the turbine and feel for any slack in the shaft.
Did you change the air filters too?
 
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Jimmy313

New member
Joined
Sep 11, 2016
Messages
2
The tap off lines shouldn't leak, there is almost no pressure in them.
Changing injectors isn't that hard, pull the old and install the new.
You mention power loss, i'm wondering if your turbo is running right. If you remove the inlet hose to the turbo, see if you can spin the turbine and feel for any slack in the shaft.
Did you change the air filters too?
Yeah I figured there wasn't much pressure in return lines just by the way the connectors push together. It's like fuel was running out of most the connectors like there was to much pressure? I'm not much of a deisel mechanic. But I read somewhere that a bad injector could cause fuel to push out of return lines? If it is a bad injector. Is there a way to find out which injector is bad? I'm guessing just removing each return line and capping it one by one while its running til I see the leak stop??? I'll check for slack in the turbine. this is prolly a no no. But last time I checked the air filters. The outer was pretty dirty. I just blew the filter out by putting a air nozzle inside the filter blowing outward trying to clean it then reinstalled it. The inner filter was bright white as tho there was no dirt build up on it so I left it alone. I also have a hydro hose leak in hose routing up by one of the rear main lift arm pins. How in the heck is a guy suppose to get his arm into some of those tight areas to change the hose. I need an arm with two elbows in it just to get to them. Lol Thanks for the quick response Much appreciated.
 

Tazza

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Staff member
Joined
Dec 7, 2004
Messages
16,829
Yeah I figured there wasn't much pressure in return lines just by the way the connectors push together. It's like fuel was running out of most the connectors like there was to much pressure? I'm not much of a deisel mechanic. But I read somewhere that a bad injector could cause fuel to push out of return lines? If it is a bad injector. Is there a way to find out which injector is bad? I'm guessing just removing each return line and capping it one by one while its running til I see the leak stop??? I'll check for slack in the turbine. this is prolly a no no. But last time I checked the air filters. The outer was pretty dirty. I just blew the filter out by putting a air nozzle inside the filter blowing outward trying to clean it then reinstalled it. The inner filter was bright white as tho there was no dirt build up on it so I left it alone. I also have a hydro hose leak in hose routing up by one of the rear main lift arm pins. How in the heck is a guy suppose to get his arm into some of those tight areas to change the hose. I need an arm with two elbows in it just to get to them. Lol Thanks for the quick response Much appreciated.
Could the hose that takes the fuel to the tank be pinched? Even if an injector was bad, there really isn't a lot of flow, no where near enough for the small line to not be able to handle it.
If an injector was bad, it would run rough all the time, you can crack the nuts at the injector to stop it working, you do one at a time and find the one that makes no difference to the running. Each one should make it run rough if they were all working as they should.
 

7LBSSMALLIE

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Feb 2, 2012
Messages
1,290
Could the hose that takes the fuel to the tank be pinched? Even if an injector was bad, there really isn't a lot of flow, no where near enough for the small line to not be able to handle it.
If an injector was bad, it would run rough all the time, you can crack the nuts at the injector to stop it working, you do one at a time and find the one that makes no difference to the running. Each one should make it run rough if they were all working as they should.
what is contstantly overlooked is the fuel lift pump screen 8mm bolt on cap on lift pump pull screen and inspect. will give indication of how much trash is fuel sys . easy breezy good place to start.
 

Jacob

Member
Joined
Sep 11, 2022
Messages
5
The return is routed back through the pump. Could his injection pump be leaking internally and causing his return line to become back pressured by the pump?
 
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