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Diesel Newbie Problems with Injector Pump

Discussion in '1982-Present GM Diesel' started by jolane, Oct 22, 2005.

  1. jolane

    jolane 1/2 ton status

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    Hello,
    I must start by saying that Diesels are completely new to me. I have never worked on one before today, but am very competent with Gas engines.
    I picked up a 84 CUCV M1008 last weekend. I originally wanted just the axles, but after doing a bunch of research on the 6.2L diesel, I am really wanting to do a swap in my 86 Burb. This truck has 48K on the ODO. I am not sure if it is 148K or not. The engine is complete though, sans good batteries. It has coolant, oil level is good, etc, but the engine had a next filling the valley. It was very dense, and the valey was filled up to the bottom of the manifold! I did not realize how deep the valley is until I cleaned it out today. I have no idea how long it has been sitting.
    Ok, to the problem. Today was my day to try to get it running. The truck is ~60 miles from my house, at my brothers house. It is a bit of a pain to drive out there. Anyways, I bought batteries for it, extra battery cable stuff, 6 gallons diesel, and took some tools. I first wired up the batteries, and fixed the cut wires. The engine turns over great. I then blead the fuel filter per the Haynes Diesel manual. I am getting fuel out of the filter mount (forget the name, something 80). I also drained the water from the filter holder, which was not much. I checked that fuel is coming out of the filter by disconnecting the line that goes to the injector pump. I am getting lots of fuel out during cranking.
    I cracked the fuel lines at the injectors, and noticed that they were already loose. Hmmm. They were just slightly loose, not disconnected. I also made sure that the fuel shutoff solenoid is energized with the key, and it is. It is flipping back and forth (took the cover off to check). I can also hear it though. I think that is all I need sfor the thing to run. The wait light stayed on for ~8-10 seconds, then turns off. The water light stays on for ~2-3 seconds, then shuts off. Seems like it is good to go. Well, I am not getting any fuel from the injector lines. I cranked the engine ~ 10 times for ~10-15 seconds. Nothing, not even a drip. I am sure I have fuel going into the pump, but not out. I took an injector line off the pump to check, and still nothing.
    What can be causing me to not get fuel at the injectors? Bad pump? No pump drive (broken gear)? How can I check further whether it is the pump or the drive?
    I took the intake off (pain!), and was going to remove the pump, but decided to stop and ask first. These are not cheap to fix/replace. What are the odds it is a drive problem? What happens if I turn the engine over without the pump in it? I did not do this, but can I to check the drive gear for missing teeth? I am not sure if I should be able to feel air or not, but when I put my finger over one of the injector line connectors on the pump, I could not feel any air or anything.
    I am also a little confused on the return line. Is this the line that is connected to the top of the governer cover? Does it actually pass fuel when everything is running correctly? Is the solenoid submerged in fuel for cooling? If there is supposed to be fuel in this chamber, there wasn't, just a slight residue on the solenoid rod.
    I know this is a lot of questions. Sorry about this. I tried a number of checks, but just do not understand the injector pump, and what it is supposed to be doing (besides pumping fuel). Does anyone have a working injector pump they would want to sell (you must know it works though). I want to get this running before I pull it.
    At this stage, the intake is off, and most of the nest has been removed. The injector lines are loose also. Where should I go from here.

    Thank you for any and all help,
    Joshua

    Today was mid-70's I think. Would I need the glowplugs for this temperature? The glowplugs are AC13's. I forgot to take my voltmeter, so I am not sure whether they are working or not. The wait light did stay on for ~10 seconds, then turn off. Does this mean anything?
     
  2. diesel4me

    diesel4me 1 ton status Premium Member

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    I'll try to help..

    I had some issues geting my 6.2 fired up for the first time when I bought it..it had a boneyard motor installed,then the owner got disgusted and sold it,because he didn't know much about diesels either,and couldn't get it started....neither did I then,other than basics that I learned from having a VW jetta diesel..

    It had bad fuel lines (rubber hoses rotted and cracked) and a plumbers nightmare at the dual tanks,which I ended up removing and going to one tank,one was leaking,and someone tore out the fuel selector valve and put a manual one it--all that went away! I did find a disconnected electric fuel pump that appeared new under the truck--I found out it worked fine,so I hooked it up,as a "pusher" pump to assist the lift pump and injector pump..it seems to help,and it makes changing the fuel filter easier--it helps bleed it out and prime the fuel system..

    --I used a bleach bottle with a gallon of diesel as a tank to "prime" it for the first time,by dunking the feed line and return line in it,and cranking it until the batteries went dead twice,then I finally got fuel--I loosened the injector lines after charging the batteries ,then fuel appeared..(BTW--a blocked return line will shut a 6.2 off!!--so be sure its not clogged,or it'll never run!)..

    But it still refused to kick..I got pissed and used ether as a last resort!--I learned its best to have the motor spinning over good BEFORE spraying any starting fluid in the intake--otherwise it binds up,and make horrible spark knock noises that CANT be good for it!..to my suprise,it fired up,and ran pretty decent!..after I let it run 10-15 minites,I was condfident it would start again..it did then,but after it cooled off,I had to use ether again..

    I tested the glow plugs with a test lamp (hook it to the + battery terminal,and touch it to the blade connector on the glow plug with its wire off--if the lamp lights,the glow plug is good..I had only 3 out of 8 working! :doah: I put a new set of G60 AC glowplugs in it(7 actually,one wont come out!),and learned how to manually overide the controller with a pushbutton switch--its started every time since for 2 years now..

    I'm not much of an expert on injection pumps either--I THINK you can look down the oil filler pipe and see the gears that drive it(might have to remove it--I never have,nor have I replaced an injector pump on a 6.2)..so you might need to ask someone who knows more about them..there must be a fairly easy way to tell if its being driven by the gears or not..I kinda doubt the injector pump isn't turning,or is bad..and they are "timed" ,so if you remove it,dont turn the engine over!..I'd leave it in,I dont think thats the problem..its not getting fuel to is my best guess..probably a blocked line between the fuel filter and the injector pump,or maybe the pump is clogged internally?..I never had the cover off one,so I dont know if the solenoid is cooled by fuel or not..

    I bet yours just needs to be bled out more,and maybe needs glowplugs..mine wont start at all without using the glowplugs,even if its 90 out!..so make sure they are good,and actually heating up..6.2's are nearly impossible to start without them working even in warm weather,at least mine is!..
    I think your wise to get this truck running first,--I'd keep it and drive it,not cut it up for parts..it could very well only have 48K on it--many military trucks here rarely leave the base!..sounds like a nice truck..

    Good luck! :crazy:
     
  3. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I think it is still airlocked by the sounds of it. You need to progressively work the air out similar to bleeding brakes. Any air at all will cause a no start.

    You already have things bled out to the IP side of the fuel filter by the sounds of it. Make sure the line going to the IP is tight. Make sure the large pink wire is connected to the IP. Remove all the glow plugs, crack all 8 injector lines at the injectors so they're loose. Now crank it over for 15-20 seconds while having someone watch for dripping at the lines.

    Let the starter rest for a minute or two and then crank it again. Repeat until you have fuel dripping at the injector. As each one drips tighten it up until all are done.

    Now check that you have functioning glow plugs. With them out of the engine you can do this with jumper cables...if they work re-install them, wait for the light to go out and with the gas pedal about halfway down try and start it.

    I've done this twice from a completely dry fuel system and it isn't much fun...

    If the IP is FUBAR it's not terribly expensive to get rebuilt. I paid $347 (which included shipping) for my IP to be rebuilt as well as 8 injectors rebuilt.

    Rene
     
  4. jolane

    jolane 1/2 ton status

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    Thank you Diesel4me and tRustyK5!
    Maybe I just did not give it enough time. This is what I know for sure:
    1. I have tight lines to the IP, and it is getting fuel from the filter outlet.
    2. I am not getting fuel at the injectors.

    It seems that the injector pump is either not turning, or that it is dry locked, or that it is restricted (does diesel gum like gasoline if it has been sitting a long time?).

    Is there anything I can do to check that the injector pump is not clogged or gummed? Can I disassemble it and reassemble it without screwing it up, or does that need to be done by a shop? What would I use to degum it (carb or brake cleaner maybe)? Is there any way to prime the pump? Finally, doesw anyone know if there is a picture of a sectioned DB2 pump (drawing most likely)? I am curious as to how these work.

    I took my charger with me yesterday incase I killed the batteries cranking it. I guess the thing to do may be to crank it with the glow plugs out, and then keep cranking it, letting the starter rest between cranking. When cranking, I assume that the solenoid must be energized (pink wire). How about the other green wire that controls the return fuel? I did not verify that it was working (I should have). I will also blow the return lines out and make sure they are unrestricted.

    Thanks again for the help!
    Joshua
     
  5. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    The three wires control pump on (pink wire), cold advance, one of the green wires, and the high idle (other green wire) As far as I can recall anyways...:crazy:

    You should have power to the pink wire when purging the air from the injector lines. I highly doubt the IP is not turning, the timing chain would have to be busted...the IP is turned gear to gear.

    Rene
     
  6. jolane

    jolane 1/2 ton status

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    That was my thought as well. I do not hear any bad noises like valves hitting pistons, which I assume would happen if the timing chain was gone. I was thinking though that maybe the pump had seized, and maybe sheared off the drive interface (long shot, but just want to make sure everything is good).

    It really does sound like I need to spin the engine for a while, and just keep going and going, until I get fuel. I am surprised that there is no way to prime the pump if it is this difficult.

    As for the return line, I assume that the internal vane pump will not draw the fuel into the pump if this line is blocked. At this point though, I do not understand the return line system. I don't understand why it has a valve, nor why each injector has two little lines coming off of them and connecting to what looks like the return line. I really wish the Haynes manual had some schematics of these systems. It is a true Haynes manual, tells you 80% of everything, I always seem to want to know the other 20%. Anyone know where to buy a Factory Service manual for the 6.2L, other than eBay?

    Thank you for your time and help!
    Joshua
     
  7. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    One thing you can check, and it is a bit of a long shot is the bolts holding the drive flange for the IP to the gear. With an ex-military truck almost anything is possibly missing. Remove the oil filler tube, and you'll be able to see at least one bolt at a time IIRC. Just rotate it by hand until you can confirm that A) it is turning and B) that all the three bolts are there.

    Rene
     
  8. arveetek

    arveetek 1/2 ton status

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    When you took the top cover off the IP, it should have been full of fuel, to the point that some spilled out when you removed the cover. From your description, it sounded like you didn't see any fuel. If so, that's the problem. Now you just need to figure out why!

    If the return line coming out of the top of the pump is blocked or clogged, this will prevent the fuel from filling the IP. What I would probably do, is remove the cover off the IP, and then have someone crank the engine over while you watch. It should start filling up with fuel, and you should be able to see the internal parts of the pump turning way down inside the center portion of the IP body. Make absolutely sure that you leave the injection lines loose so that the engine can't start. If the engine starts with the top cover removed, you won't be able to shut it off without starving the engine of air or fuel.

    If the IP begins to fill up with fuel with the top off, then the problem is in the return line. If it doesn't fill up, then the problem is in the fuel inlet of the pump.

    There is a check valve in the top cover of the IP that could be causing your problems. If it won't allow fuel out of the IP into the return line, it can be temporary removed to see if the engine will start.

    Fuel is pumped from the tank, through the filter, into the pump, and out of the return line back to the tank. Excess fuel is also given off by the injectors. All this fuel is returned back to the tank, serving two purposes: to cool the IP in the summertime and warm the fuel in the wintertime.

    Casey
     
  9. jolane

    jolane 1/2 ton status

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    Wow! Thank you very much everyone! I think that after these posts I know what to look for. After looking around for more information, it appears that the check valve on the top cover is controlled through a switch on the rear of the passenger cylinder head. I did notice that this sensor's wire is cut (actually , my brother noticed it). This means that the return line is effectively clogged. I will get this taken care of first.
    As for not seeing fuel inside the pump cover, that is correct. I only saw minimal residue, but for all intensive purposes it was dry. I guess the thing to do is:
    1. Fix the sensor and verify that the check valve is releasing.
    2. Take all of the injector lines off.
    3. Take all of the glowplugs out.
    4. Take the IP cover off.
    5. Having someone else turn the engine over, look down into the pump and verify that it is turning.
    6. Keep cranking (with rests of course) until fuel starts filling up the reservoir, or fuel starts dripping from the the injector lines.

    If this works, I guess it will be time to try reassemble, and bleed the system. Hopefully it will fire.

    If it does not, I guess I need to look at the glow plugs. Currently they are AC13's. What is the consensus on glow plugs around here. It seems that the AC60's are too slow for use with the stock controller, and that they seem to have a short life. What would you buy for your own engine if it had a stock controller?

    Again, thanks to everyone for the help! I really appreciate your time!
    Joshua
     
  10. arveetek

    arveetek 1/2 ton status

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    You've almost got it! :D

    The check valve in the cover is just that....a check valve. It's the part the return line hose is hooked to. The other valve you mentioned, the one controlled by the switch on the head, is called the HPCA...Housing Pressure Cold Advance switch. What it does is raise the fuel pressure inside the IP when the engine is cold, thereby advancing the timing, which aids in starting. The switch on the head is just a temperature switch. When the engine warms up, it opens that switch and kills power to the HPCA, causing it to return to normal timing.

    When the engine is cold (i.e., not up to normal operating temperature) and the key on, use a test light to check if there is 12+ to the HPCA terminal. You should also be able to hear it 'click' when touching the wire to the terminal. If not, just simply jumper a 12+ wire from the battery to this terminal to aid in starting. You can trace that problem down later.

    The check valve in the cover can become clogged and not allow air/fuel to escape from the IP. That is the doohickey screwed into the cover, that the return line fits onto. It prevents unfiltered fuel from going back into the IP.

    Also, when you bolt the top cover back on, make absolutely sure you get the fuel cut-off solenoid positioned correctly. It's easy to bolt the cover on and get the cut-off plunger jammed. If this happens, and the engine should start, it could run away and you won't be able to shut it down. When you set the cover on the pump, keep it slid towards the front until the cover is touching the top of the pump, and then slide the cover back into position. When bolted on, verify you've got it right by touching the wire to the shut-off terminal and listening for a 'click' (ignition key on).

    As for glow plugs, I have AC60G's in my truck that are over 2 years old now. I haven't been able to burn one out yet. They do require a little longer glow time, though. If I were going to buy new plugs, I'd buy a set of "quick-heats" from www.kennedydiesel.com.

    Casey
     
  11. jolane

    jolane 1/2 ton status

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    Arveetek,
    Thank you very much! I will print this out and and take it with me! I was unsure how to put the cover back on, so I will have to check that part. Thanks for mentioning that and telling me how to do it correctly.
    Joshua
     

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