I have an '82 K20 with a 6.5 block / 6.2 top end, it has been running fine up to the weather getting colder, so I put new 9G's in it (before I knew better) - it started ok for a few weeks then got harder to start (embarrassing at work). I have good voltage to all glow plugs (manual operation - system overide), thought it must be the mechanical lift pump as it didn't seem to be getting fuel so changed it out, changed fuel filters, still no go. Cracked all injector lines to bleed air and they all wept fuel after cranking. Am I looking at a new injection pump or ?

Frustrated and out of ideas.

If you have fuel coming out of the cracked lines when cranking, the injection pump is working. Take the wires off the glow plugs and attach a test light to the positive battery post, so when you touch the test light probe to a ground the light comes on. Then touch each glow plug post. The light should come on which means the circuit in the glow plug is good and it should work. If the glow plugs are all good I would then do a compression test to see the shape of the engine.

Ditto to checking the glow plugs. Test light with one end to battery + , touch other end to glow plug spade. If glow plug is good test light will light(you will simply be completing circuit to ground. Make sure that wire is off of spade before you check each glow plug. 9g plugs could be your problem. They are very easy to burn out. They are a 6volt plug that heats real fast with 12 volts. As soon as practical change to 60g plugs. They are dual core self regulating and you can leave them on as long as you want and they won't burn out. 9 g's can burn out in as little as 11 seconds and when they do they often leave a bulge or a tit that can be very dificult to remove. If you have problems let me know as I know a few tricks to get out 9 g's without removing the heads. Hope this isn't your problem. For emergency use carry a can of starting fluid, use it after your glow cycle is completed, best to have a helper spray it into the air cleaner while you crank. Don't use too much. This trick works for my daughter on her 6.2 when it is very cold and dad's not around.;)

Thanks for the help guys, test light works on all plugs, so gp circuit is good. Truck did not show any signs of weak compression, doesn't smoke and runs like a top - do I need to pull the intake to remove the injectors? Before this no-start condition, I could see smoke from tailpipes when cranking now I don't - is it possible that the inj pump isn't pumping enuff fuel to the cylinders? Has 2 newer batteries, cables & connections are good. Thanks in advance for your input.

I would only use Delco 60G glow plugs as I have never seen one of them mushroom. They do take longer to heat, but some people leave them on for a minute without damage (that would burn out 9G's and 11G's with probable mushrooming). I have a manual switch and I leave my 60G's on for 20 seconds in cold weather. My first step would be to put in 60G plugs as I would not trust 9G, 11G, or Champion 77's. Why don't you hook up each type separately with alligator clips (out side the engine) to see how they heat up. I had some 9 or 11G's that would pass the test light, but when I took them out of the engine and checked them with alligator clips then they didn't heat up properly.

And please don't use ether or starting fluid because you can damage your engine!!!!

Weak injection pumps will still have sufficient pressure to weep fuel if you loosen the fuel line at the injector, but not have sufficient fuel pressure for proper fuel atomization at the injector nozzle. Weak injection pumps will usually cause hard starting in cold weather. Injectors that leak prematurely will also cause hard starting (they usually cause engine knocking too).

It is starting to sound like a fuel problem. What type of filter system do you have? Have you checked fuel lift pump for output? No smoke means no fuel. It is possible that you have an air pocket in your filter system. A good test is to remove the rubber hose that comes out of the top of the injection pump and goes to the fuel return line. Replace it with a piece of clear hose. Crank engine and look for air bubbles. If you have air bubbles you will need to locate the source of the air leak. If you have 82 vinage screw on filter housings the primary filter has a bad problem of casting porosity that can suddenly result in loss of prime. Remove primary filter and see if it is all the way full of fuel. If it is as little as 1/2 inch below the top air can get sucked into the injection system resulting in airlock and no start. Refill filter to the top and spray WD 40 into the intake after you cycle the glow plugs. You can start the engine with the WD 40 without doing any damage and it will make life easier on your starter by helping the engine spin over faster. 6.2's DO NOT require loosening the injectors lines to purge air, but it does require several minutes of cranking to fully purge the air from the lines. I use this procedure exclusively whenever I rebuild a diesel engine and it works flawlessly. P.S. The danger of starting fluid is that it can ignite when the glow plugs cycle, which is why it needs to be used with the glow plugs off and the engine cranking. Also most starting fluids of late are not as HOT as they used to be and don't have a real good pop anymore. They won't even pop to seat beads on tires in emergencies like they used to. Let me know if this helps. D. Camilleri ASE Mastermechanic

Actually I replaced the mechanical lift pump (wished I would have put an electric pump on), new filter filled within 1/2" from top, previous owner removed secondary filter and mount and went with an inline second filter, (I would like to replace the mount and original set-up - any idea where I can get one) there is also a check valve installed between second filter and inj pump. I'm guessing that this to keep the fuel from draining back. I have the charger on to top batteries and will check for bubbles and try what you suggest with the wd40.Thanks for the helpful suggestions.

I probably have an old secondary filter lying around in my pile of parts, but I would recommend changing to the later style 6.2 filter housing used from 84 up. Keep your current in line fuel heater and wire the fuel heater with the newer style so you have two fuel heaters. The biggest benefit of the later style is that fuel is pushed from the lift pump to the fuel filter, whereas the early style fuel is sucked from the primary filter to the lift pump and then pushed to the secondary fuel filter. An in line fuel filter in place of the secondary fuel filter is probably not a very good idea. The stock 6.2 secondary fuel filter is about a 2 micron filter, most inline filters will allow much larger particles to pass and possibly damage your injection pump. There is also a possibility that you have small amounts of water in your fuel and the water has collected on the primary filter and plugged it(iced up). The fuel heater on your truck heats the fuel before it goes to the secondary filter, so it would be of no help if the primary filter has iced up. At any rate first thing to check would be crank engine with secondary filter disconnected and fuel hose running into a container and see if you have ample fuel to the injection pump. Next check for air bubbles in the clear line that you will install and third, dis connect the clear line and try to start. A plugged fuel return line will result in a no start. Fuel should flow freely from the line on the top of the injection pump while cranking. There is also a check valve before the rubber line on the injection pump top cover, if this check valve becomes clogged-no start. Usually the check valve gets clogged from internal pump failure. Hope this helps.

Back in business, thanks to all who helped - DC the clear hose showed a lot of foam from the ip return. Traced back to the primary filter mount bleeder on top of the filter head. Pulled it off & cleaned of deposits with a small file. Added electric fuel pump before filters. Running fine as of today. Thanks again for your help.

Glad to help. These little problems have frustrated a lot of people in the past, air leaks can be a pain.:cool2: