804A Fuel Return Question

[FLCarguy]

Hi all,
First post, I picked up a MEP-804A with relatively low hours that needs a few things worked out. I downloaded and studied the TM manuals, thank you! I have been working through the issues and only have two left. One is the unit runs pretty rich. I suspect one of the injectors is stuck open or not closing all the way and am going to pull and clean them today. The question I have is how much fuel should I have coming back from the fuel return line? I removed that line and put it in a plastic jug, ran the unit for about 10 minutes and had NO fuel come out. Besides a blockage in the line would a stuck injector cause this also? Seems like I would still get some back out.

Thanks,
Jay

 

[Guyfang]

Since you have downloaded the TM's, open TM 9-2815-254-24. Turn to PDF reader page #50. Start reading at Para 3-10. Read until page 57, stop at para 3-11. Most of your questions, and how to properly remove, clean, test, adjust and properly reinstall the Injectors is spelled out in detail. There is no set amount of fuel dictated by the TM, for output of the injectors. But the chart showing spray pattern will help you adjust the injector, if need be.

 

[FLCarguy]

Since you have downloaded the TM's, open TM 9-2815-254-24. Turn to PDF reader page #50. Start reading at Para 3-10. Read until page 57, stop at para 3-11. Most of your questions, and how to properly remove, clean, test, adjust and properly reinstall the Injectors is spelled out in detail. There is no set amount of fuel dictated by the TM, for output of the injectors. But the chart showing spray pattern will help you adjust the injector, if need be.

Thanks for the response, especially on a Holiday. I have been studying that section pretty intensely. I got the injectors out, and cleaned but I need to use my friends injector tester to test and set the spray pattern before putting them back in. This unit had a bunch of issues but the final one is that it starts right up no problem but runs super rich, strait black smoke out the exhaust. You shut it off and it won't turn off, just keeps running. Before it kept running rich but I found that the governor nut was not set right and the rack in the pump was not going over to full shut off. i adjusted that and now it shuts right down if it is cold but if it runs a while, you turn S1 to off, hit the EMO, whatever, it just keeps running but runs very "clean" and almost normal. Even the temp goes down a little. It will run like this at least 10 minutes before running out of fuel. It runs like this even with the tank fuel lines disconnected. It does not appear to be sucking oil out of the crankcase as the level does not seem to change. Also the RPM stays steady. This is why I suspect the injectors are dumping fuel more than they should. I am also going to check the injector pump timing once I figure out what the "z marks" on the timing gear are! Someone has worked on this issue before on this unit as I can tell that the injector pump has been removed and worked on.

 

[Guyfang]

This doesn't sound like a timing problem. The actuator is not adjusted correctly. When the S1 is turned to OFF, the power to the actuator is also turned off. Then the actuator should retract, causing the I.P. to stop providing fuel to the engine. Try this. Pull the electrical connector back a bit from the actuator. Measure from ground to the terminal. Should be 24 volts. Have someone turn off S1, while you hold the Meter to the electrical connector. When the S1 is turned off, is the power to the actuator gone, or not?

It was not a holaday here in Germany. Every day is a holiday for someone retired. Having written that, I am so busy right now, I am ready to go back to work.

 

[FLCarguy]

This doesn't sound like a timing problem. The actuator is not adjusted correctly. When the S1 is turned to OFF, the power to the actuator is also turned off. Then the actuator should retract, causing the I.P. to stop providing fuel to the engine. Try this. Pull the electrical connector back a bit from the actuator. Measure from ground to the terminal. Should be 24 volts. Have someone turn off S1, while you hold the Meter to the electrical connector. When the S1 is turned off, is the power to the actuator gone, or not?

It was not a holaday here in Germany. Every day is a holiday for someone retired. Having written that, I am so busy right now, I am ready to go back to work.

Hi,
Yes I was thinking the same thing so I ran that test on the actuator, I also applied 24v to it to watch it move and see if it was not binding. It was not, I also put my meter on the leads while the unit was running and it appeared the governor control module was sending the correct signals. I also took off the inspection plate on the injection pump to see if it the rack was moving all the way to the right when it is off and at first it was not. It was only moving to about 1/2 a mm from the stop. That is why I adjusted that nut so it would go all the way over to the right hardstop. I guess its possible that someone worked on the pump and the rack itself is not adjusted correctly but when you move it to the "center" all four are lined up correctly. I will say that the rack seems to move more to the right then to the left but not by much. The TM says it should be even. I don't really want to rebuild the pump as it looks like you need quite a few special tools but I think taking it apart is the only way to "reset" that rack. Do you know how the rack actually turns off the fuel? I assume it puts the plungers in a position that they cannot move up and down with the cam? Sorry for so many questions but that part of the pump is not described too well in the TM. Also on page 70 of the technical Manual it talks about the "delivery valve" Item 35. I am going to pull and check this but could this continue to allow fuel to flow?

 

[FLCarguy]

Hi,
Yes I was thinking the same thing so I ran that test on the actuator, I also applied 24v to it to watch it move and see if it was not binding. It was not, I also put my meter on the leads while the unit was running and it appeared the governor control module was sending the correct signals. I also took off the inspection plate on the injection pump to see if it the rack was moving all the way to the right when it is off and at first it was not. It was only moving to about 1/2 a mm from the stop. That is why I adjusted that nut so it would go all the way over to the right hardstop. I guess its possible that someone worked on the pump and the rack itself is not adjusted correctly but when you move it to the "center" all four are lined up correctly. I will say that the rack seems to move more to the right then to the left but not by much. The TM says it should be even. I don't really want to rebuild the pump as it looks like you need quite a few special tools but I think taking it apart is the only way to "reset" that rack. Do you know how the rack actually turns off the fuel? I assume it puts the plungers in a position that they cannot move up and down with the cam? Sorry for so many questions but that part of the pump is not described too well in the TM. Also on page 70 of the technical Manual it talks about the "delivery valve" Item 35. I am going to pull and check this but could this continue to allow fuel to flow?

Hi all,
Little update but no progress, I pulled the injectors, cleaned the lines, took apart, soaked and cleaned the injectors. Before cleaning the spray pattern was pretty decent but the pressure that they popped off was not at 1700psi like the book states, some were as low as 1000 and some as high as 2200. I re-calibrated them and reinstalled. Machine still runs the same as it did, very rich and will not turn off. Suspect now that injection pump is not turning off the fuel even though the rail is all the way to the right at the hardstop. I disconnected the lines at the top of the injection pump and cranked the engine with the fuel rack all the way to the right (off position) and there was still fuel coming out the tops depending on what cam was moving. I suspect this is not suppose to happen? Anybody have any thoughts?

 

[Guyfang]

This doesn't sound like a timing problem. The actuator is not adjusted correctly. When the S1 is turned to OFF, the power to the actuator is also turned off. Then the actuator should retract, causing the I.P. to stop providing fuel to the engine. Try this. Pull the electrical connector back a bit from the actuator. Measure from ground to the terminal. Should be 24 volts. Have someone turn off S1, while you hold the Meter to the electrical connector. When the S1 is turned off, is the power to the actuator gone, or not?

It was not a holaday here in Germany. Every day is a holiday for someone retired. Having written that, I am so busy right now, I am ready to go back to work.

Did you ever do this test? Because if the 24 VDC turns off, the solenoid is supposed to cut off fuel from the fuel source to the IP. Every diesel has this system, to prevent "Run on".

 

[FLCarguy]

Did you ever do this test? Because if the 24 VDC turns off, the solenoid is supposed to cut off fuel from the fuel source to the IP. Every diesel has this system, to prevent "Run on".

Hi,
Yes, see above. I tested the solenoid pretty extensively. The rack is all the way to the right (I assume this is the shut-off position) at the hardtop when there is no 24v . It physically cannot go any further. I think something is leaking past in the injection pump or one of the plungers is installed backwards if that is possible. Today I am going to remove the lines from the top of the pump and pump the fuel while cranking and see which line is passing fuel through.

 

[155mm]

Sounds like actuator is installed incorrectly, that part is a pita to install correct.

also dont forget to refill the oil in the back of the injector pump under the actuator

 

[FLCarguy]

Sounds like actuator is installed incorrectly, that part is a pita to install correct.

also dont forget to refill the oil in the back of the injector pump under the actuator

What make you say that? Just curious, the rack is all the way to the right which I assume is off? Even with the actuator disconnected. But still fuel gets through. I did a test today with all the lines disconnected and with the rack all the way over and cranking the motor and the second from the rear line was still pumping fluid. I don't think that should be the case. I am cleaning out the injector pump top section today. It was pretty gritty inside.

 

[155mm]

I had to replace an ip, and i installed the actuator incorrectly, that was the same issue i had, have you checked your magnetic pickup

 

[FLCarguy]

I had to replace an ip, and i installed the actuator incorrectly, that was the same issue i had, have you checked your magnetic pickup

I do appreciate any input on this. That is exactly what I originally thought as well and it was a bit of an issue. it was not allowing the rack to go all the way over to the hardstop. I actually had to to cut the end of the shaft on the actuator a bit to get the black pin holder in the right spot. (This is not the original barber Colman valve it is a Woodward.) This made it a bit better but still did not resolve it.

 

[FLCarguy]

Hi all,
First post, I picked up a MEP-804A with relatively low hours that needs a few things worked out. I downloaded and studied the TM manuals, thank you! I have been working through the issues and only have two left. One is the unit runs pretty rich. I suspect one of the injectors is stuck open or not closing all the way and am going to pull and clean them today. The question I have is how much fuel should I have coming back from the fuel return line? I removed that line and put it in a plastic jug, ran the unit for about 10 minutes and had NO fuel come out. Besides a blockage in the line would a stuck injector cause this also? Seems like I would still get some back out.

Thanks,
Jay

I Fixed it!!!!!!!!!!
So I did the test with the fuel rack in the off position, the injector lines off, and cranked the engine with the manual crank switch. As I said previously the #2, from the Genset injector port was still pumping fuel. I took out the metering valves and soaked them along with the cylinder housing, when I reinstalled them I noticed that #2 was not going all the way to the hardstop as the others were. It was about .030" off. i was able to adjust the plunger on the rack by tilting forward in the "cylinder" above. This allowed it to align with the other three. Also I found there was a lot of debris in the upper part of the pump. I cleaned all of that out, put it back together with and tested again with no lines connected, This time no fuel was coming out with the rack in the off position. I put it all back together and it runs like a dream! Shuts right down when switched off. To say I am excited is an understatement! lol Thanks for all the help!