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Is My 6.2 Dead?

Discussion in '1982-Present GM Diesel' started by carlos442, Apr 14, 2004.

  1. carlos442

    carlos442 Newbie

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    Hello All.

    I'm at a loss for what is ailing my 6.2. First here's what happened..

    While driving home one evening, I really opened it up. Ran full-throttle for about a mile, which isn't even topended. At the end of this the engine cut out and I heard a noise from the backend "almost" like a backfire, but not quite. I let off and it ran fine the rest of the way home, about another mile.

    The next day I tried to start it and it wouldn't start. So I decided to change the fuel filter, and if that didn't work I'd check the fuel pump. I changed the rectangular filter on the firewall, following the Haynes manual to the letter. It still wouldn't start, which didn't surprise me. A friend of mine said to try starting it with ether and if it would start with ether, run a few seconds, then die, it was starving of fuel. Sounded reasonable, as I had used ether in the past in a few shops I worked for to start vehicles.

    I bought a can of starting fluid that said safe for gasoline AND diesel engines in big letters, turns out in the fine print, it said it was not intended for glow plugs. You know what's next... since I didn't even realize diesels without glow plugs existed (I learned now that many don't have them,) I neglected to disconnect them. It didn't even rotate a full time before the engine seized up.

    I got it unstuck with a come-along and a tool I made the same friend weld up for me. /forums/images/graemlins/wink.gif

    So now I think I just need to track down if its the fuel pump. I can't get any fuel to come out of the air purge vent on the new filter I installed. That's where I got stuck on the filter change and decided to see if the fuel pump was bad.

    I hesitate to buy and change the pump if I hurt the motor with the ether. This brings up a few questions... first, will a 6.2 run on ether alone if its getting no fuel, even for a second? When I try to use ether, with the glow plugs disconnected this time, it cranks fast unless there's ether present at which point it cranks VERY hard until all the ether is gone. It never sounds like its firing. Just cranking.

    Second, is simply this... if that scenario with the failed ether starts is not what I should expect to be happening, does anyone have any ideas about how much damage I may have done with the ether based on the symtoms I'm describing?

    Any help would be greatly appreciated. Thanks in advance! /forums/images/graemlins/smile.gif
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    When I recently did my filter change I pre-filled my Racor and new canister filter, then with the pink wire to the injector pump disconnected and the fuel line after the second filter undone I cranked it over for about 10 seconds at a time until I had fuel coming out of the line. Then I reconnected the fuel line and the pink wire and it fired up without even running a little rough.

    I guess we can assume your glowplugs work... /forums/images/graemlins/eek.gif

    You might want to do a compression check after the ether incident. Trying to diagnose engine condition and stuff using ether isn't going to tell you much. I would think you probably did some damage if you had to 'free it up' using a come along contraption. What basically happened is that a few cylinders fired at the same time which could cause all sorts of major damage.

    Rene
     
  3. carlos442

    carlos442 Newbie

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    Thx for the post, Rene. /forums/images/graemlins/smile.gif

    I wasn't able to get any fuel to the filter when I changed it. I'm going to try a new fuel pump this afternoon, and if that doesn't get it running I'll get the stuff to run a compression test. I am really afraid it still won't run, or won't run right when I finally get it going.

    I was thinking about throwing in a big block, but last night I read a cool article about propane injection on diesel engines. Now I want to get this one going so I can play with that. I've converted gas engines to dual fuel propane/gas before. I think I'll hold off on the big block thing for awhile.
     
  4. cegusman

    cegusman 3/4 ton status

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    Fill out your profile. Someone close to you might be able to help you out.
     
  5. carlos442

    carlos442 Newbie

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    Profile updated! /forums/images/graemlins/smile.gif

    Today I changed the fuel lift pump and succeeded in getting fuel through the Model 80 filter.

    Still not starting. I figure I'll try to search here for the procedure to bleed the air out of the injector pump and lines.

    I cracked the lines at three of the injectors and nothing spilled out, so I'm guessing there's air in there. If there's fuel to the injector pump, why wouldn't the Inj. pump simply force the air on through the injectors? Does it have to do with the air being compressible and not being able to force open the injectors?

    I wish I knew more about diesels. /forums/images/graemlins/smile.gif
     
  6. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    It's definitely air locked now. The injector pump sends a short high pressure spike down the fuel line which 'cracks' the injector making it spray a minute amount of fuel. any air in the line will just absorb that pressure 'spike' and nothing will come out of the injector.

    Pull all the glow plugs out so the motor will crank over easier. Loosen all the lines. Have a helper crank the motor over for 15-20 seconds at a time as you watch the injector lines. As soon as you see one start to weep and drip tighten it up. Remember to have the pink wire connected on the injector pump. When all 8 lines have dripped and been tightened re-install the glow plugs and try and start it up.

    Oh yeah...be careful with the starter. Crank for 15-20 seconds and then let it cool for a minute before cranking again.

    Rene
     

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