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Thread: Injector pump timing mep-003a

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    Default Injector pump timing mep-003a

    I am trying to set the injector pump timing on my 003a and am having trouble. If I turn the engine clockwise while on the blower end and watch the valves for #1 cylinder (the cylinder on the blower end) the exhaust valve closes and just before the intake valve opens the PC mark is lined up with the pointer on the flywheel. The manual makes me think the pc mark should be on the compression stroke and not on the intake stroke. If I set the timing with the procedure in the manual I will have the fuel injecting right when the intake valve opens. I have attached pictures of the flywheel marks that my genset has (The PC mark didnt show up in the picture but the marks above and below it are visible). After rotating the engine clockwise from the PC mark I see an A and then a bunch of random marks and then a B.

    What am I doing wrong here guys? Also, thank you in advance for any help.
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    Your thinking is correct, PC should come up almost 1/4 rotation after the #1 intake valve closes and the compression stroke begins. The A and B marks I believe are references for valve lash adjustment. It's mentioned somewhere in the TM.
    Can you give us the history on this machine? Is it new to you, does it run, did it ever run? This info will help us figure out what's going on.
    When the flywheel is at the PC mark, does the 1/8" drill bit seem to align into the slot in the injection pump gear, when you remove the little screw on the left side of pump?

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    The generator is new to me. It shows 377 hours and the only markings on it say that the fan bolts got changed. It had obviously been sitting for many years before I bought it and I changed the oil and filters and flushed the fuel tank, lines, and strainer. After this the generator would run for a minute or two and start loading down and smoking (black smoke) and then die and the cylinders seemed quite hot. I tried running it a second time while watching the shut off solenoid to make sure that wasnt the issue and the oil pressure looked great too. After researching it seemed like the IP timing was out 180* so I adjusted the pump so the slot was lined up with a drill bit at the PC mark. After this I moved on to the flow test and realized I had an issue when they said the fuel would begin to inject at PC.

    The TM made it seem like the flywheel is only held on by a taper and no key or anything so I am thinking that it may have shifted at some point. None of the bellhousing bolts look like they have ever been touched. The generator is messy but for something that lived in Maine its not bad at all.
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    If the IP were 180 out, the engine would not run or start.

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    The flywheel is held to the crankshaft with a taper fit and a key. It's possible the key sheared off and the flywheel has spun, but that is fairly unlikely. Also, if that had happened, you would not be able to get the drill bit to align with the IP slot while the pointer is at PC. The IP would remain correctly timed to the engine and only the PC mark would be out of alignment. I think we need to do more investigation before you pull the engine off to check the flywheel.

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    Since you say it sat for years I'm wondering if you might have a stuck or malfunctioning injector(s)? If they sat for a long-long time any residual fuel may have gummed them up. That might cause it to run hot as you described. You could take all your injectors to a fuel injector shop, or see if anyone here on SS has the ability to do it, and have them ck pop-off pressure. FYI - New fuel injector nozzels run about $200 ea on eBay. Search on "147-0136 Onan Fuel Injector Nozzle MEP002A MEP003A NSN 2910-00-869-5".

    At the very least, you should take them out inspect them visually and put them in a cleaner (Seafoam, Acetone, etc.) and let them soak overnight. I have a ultrasonic jewelry cleaner that I often use to put small parts in. The ultrasonic action gradually heats up the solvent and you would be amazed at the crud that ultrasonic cleaning works out of small parts.
    Last edited by Chainbreaker; 08-06-2019 at 11:15.
    GEN #1 House Gen PU-751/M: 1986 MEP-002a/M116A2 w/Aux Tank & OEM cover
    GEN #2 Spare Gen PU-751/M: 1991 MEP-002a/M116A2 w/Aux Tank & OEM cover
    GEN #3 Shop/Barn Gen NF-2 Enclosure: 19XX MEP-002a w/Aux Tank
    GEN #4 Spare Gen PU-751/M: 1991 MEP-002a/M116A2 (a work in process)

    * Disclaimer - My comments on this forum are based on my opinion and my experiences only. It is your responsibility to verify any information before using or to hire a professional.

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    While I never really trust the TT, (Time Totaling Meter) from the look of the set and hour meter, I think you should try going back a step, or two. The symptoms you describe, don't sound like a timing problem to me. When the set ran, did the volt/hertz meters come up? Will it start now?

    Like Ray, I think its very unlikely that the flywheel has spun. Eight years of running a DS shop, and we never had a failure like that.

    Like chainbreaker, this sounds much more like a fuel/fuel delivery problem.

    In picture number 3, I noticed the exhaust elbows not directing the hot gasses away from the battery tray. The reason the elbows are there is to keep the batteries from over heating. So unless you have a need to vent the exhaust differently, you should do that. You can see the exhaust has been blowing down onto the fuel tank also. Not good.
    Last edited by Guyfang; 08-06-2019 at 11:19.

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    When you do the IP timing, be sure you hold the throttle wide open. Begin with the motor set so PC is slightly below the pointer. turn teh pumps on and watch the fuel flow from port #1. Rotate the motor slowly until fuel flow stops. the pointer should now be very close to the PC mark. If so I suspect you have 1 or more injectors that are either leaking or sticking open.
    If that's the case I am set up to repair and pop test them. You can also replace the needle and nozzle with the gaskets. the kit is $50 ea. on ebay.

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    I removed the injectors and cleaned them and replaced the gaskets before starting the unit and replaced the glow plugs. The injector pump slot didn't line up with the PC mark on the flywheel at first but I lined them up and then moved on to the flow test. At that point I realized PC was when cylinder 1 would start injecting fuel and that should be just before the top of the compression stroke. The problem is that PC on my unit is lined up with the pointer right at the start of the intake stroke. I tried the flow test with the throttle wide open after re-timing the IP and it is on but I dont want to start the generator because I am afraid of damaging it. I turned the exhaust elbows so they are pointing away from the fuel tank and batteries. There is fuel returning to the tank and all of the lines got flushed out before the first start.

    The thing is that the voltage and frequency meters are not showing anything on the unit and I started it up with a multimeter in the auxilary outlet and once I got that set to 60hz it was only showing a little over 4 volts. I figured I just needed to flash the field once the engine was running properly.

    The thing that gets me is that black smoke will roll out of both pipes as it starts to die so that makes me think that the IP is increasing fuel to more than one cylinder at the same time. That makes me think that its not an injector issue and also not a lack of fuel issue.

    Thank you for all of the replies too! Hopefully I can figure this thing out without pulling the engine off.

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    So as of now, the flow test was successful and the pin inserted into the IP slot and flywheel PC mark are in alignment, correct?
    My thinking is that since the IP drives off the cam, if the flywheel had sheared the key and spun, I would expect it to be impossible to align the PC mark and actual fuel shutting off due to the cam being way out of sync with the flywheel, but maybe someone else can chime in and confirm?

    Maybe you can remove the #1 injector and use a small wire down the cyl. to feel the piston come up as you rotate the motor and try to find TDC and see where the flywheel compares to the piston movement?

    Pull the motor or gen as a last resort, although its not that hard at all.
    Good Luck!

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