GMC Jimmy chugging

biggestmexibiggestmexi Member Posts: 2
edited July 2014 in GMC
I just started looking at this board today seems great. Especially repair dog.

The problem I am having has occured and got worse over a couple months. It will start perfectly fine. It then at start at about mid RPM range start to chug then running a minute longer it will over come the whole RPM range and wont be able to accelorate and then sometimes putt out. But then not even 10 seconds or as soon as possible i can restart and then have the same problem. It has a recently new pump(4months), new plugs-wires-cap-rotor(yesterday), new fuel filter last week. Cleaned the TPS and IAC. Removed and blocked EGR. Took care of a couple vacuum leaks I could see. Fuel pressure tested OK and volts to the pump was right around 13.7. The oil seems a little gassy to me but not exactly sure. There is no smole out of the exhaust and no cat. Also i am going to try to clean the map/f sensor soon but where is it at. I am at work now no chiltons


  • jnewnamjnewnam Member Posts: 1
    I am having basically the same problem it runs pretty good until its heats up then it just seems as if gas is being dumped it to the engine i replaced the spider injectors and it runs better because my intake was full of gas but then it still wasnt running the way it should so i replaced the cap rotor plugs and wires but its still doing it does anybody have any suggestions i havent replaced the coil yet but im getting kind of tired just throwing parts at it because it is kind of expensive so if anybody can help me i would appreciate it
  • biggestmexibiggestmexi Member Posts: 2
    I ended up taking my jimmy to a mechanic and he did a Vollume test on the fuel system. Needless to say it failed. Changed the pump and all ok.

    I would suggest changing the fuel pump. It was only like 60 dollars. FAR cheaper than the spider system. and i got a 1 year warranty.
  • stanman7stanman7 Member Posts: 2
    Well, I just turned sixteen a few months back, and a '94 jimmy was my first car. The person who I bought it from was selling it due to something that he thought was a gas leak. The car did exactly what you explained; it would start up, run for a while, and then stall out. after replacing the cap/rotor/plugs/wires, it still didn't fix the problem. Then I got word from a car mechanic saying that one of the main problems that he encountered with jimmys was with something called the "nut kit", which is the part of the fuel line that's under the engine head. Turns out, that was the problem. I took off the engine head, turned the key, and gas started spraying out of the broken part of the nut kit. Of course, replacing something like this is taking me a while, especially with the cold weather.
  • pcgeekpcgeek Member Posts: 6
    That sounds like the 'nut kit' needs to be replaced. If the oil is gassy, or the exhaust smells rich or gas drips off the back of the engine, spend the $40 on the kit. It made a big improvement for me.

  • garys_njgarys_nj Member Posts: 1
    I think the "nut kit" you're referring to is the gas feed and return lines to the CPI (Spider). I have a problem with my s-10 blazer 4.3 vortec where it stalls and then won't restart without either (and then still sometimes won't start). I tried a couple things fixed some vacume leaks and changed spark plugs. it always had a lopey idle, now much worse idle and still stalling.. I removed the plenum and see a lot of gas in the intake belly around the spider and the gas feed line is almost worn through (contact with a poppet line). with pressure, I only see a weep from the feed line but I'm changing the spider and the feed/return lines (the nut?). seems like there's a bolt on a holding plate for the feed/return nipples) but I can't get a wrench or socket on it. anyone know how to replace the feed/return lines??
  • tony2980tony2980 Member Posts: 2
    its not a nut its a star head to change those lines after you remove the star and the plate the lines slide out i had to use a tool that looked like an L shape they sell them at auto zone in a kit it was like 9.99 itwas a t30 ithink its been awhile or a t15 torx head thats what they are called
  • tony2980tony2980 Member Posts: 2
    my blazer cranks up and runs but it sounds and idles like i have a big cam in it it runs really rough but at 65 70 it runs alot smoother i had it checked out at shop because i kept changeing stuff and my pockets are not that deep they are tellin me its the spider injection cpi unit and its kinda costly any suggestions
  • dblackmerdblackmer Member Posts: 1
    is there a site that give instructions on how to replace the nut kit? The nut kit that goes on the feul feed and return lines
  • majiktikimajiktiki Member Posts: 3
    replaced fuel pump/filter/catalytic converter/o2 sensor/tps/egr valve/temp sensor to ecu/ one of the injector. works fine then doesnt. entermittent.cept for when i get near mech. then works. even after not working...chugging loss of power rough idle . like not getting gas. but strong gas smell.(thinking about replacing brain??? HELP.
  • twontonetatwontoneta Member Posts: 1
    so is the nut kit thing your talking about
    really under the head were the pistons are
    or are you talking about the top part of the engine
    itself ?? :)
  • joegmcjimmyjoegmcjimmy Member Posts: 1
    My Jimmy has the following issue:

    1. Turn the car on
    2. Put in gear and press on the accelerator.
    3. Engine doesn't seem to do anything, sometimes a little chugging.
    4. Let-off on accelerator.
    5. Press accelerator again, all seems good, power to engine.

    Anyone have a clue what this might be?
  • stanman7stanman7 Member Posts: 2
    The nut kit is underneath the plenum, which is the top part of the engine that's visible when just looking at the engine.

    If you take off the plastic cover with the orange "4.3 Vortec" on it, then it's the metal cover underneath that (you don't have to take that off, but it helps). The nut kit should be located in the back of the engine, where the fuel lines come into the engine (between the engine and the firewall).

    First, with the plenum off, and full-visibility to the nut kit, you should have someone put the key into the starting position. Don't start the car, but turn the key into the "on" position so that the fuel pump starts up and puts gas through the nut kit. If gas spits out anywhere, then you've got a bad nut kit. If there isn't gas spraying anywhere visible, then you've probably got a bad fuel pump, or leaky lines.

    If you have a bad nut kit:
    Using a wrench, you should be able to get the fuel lines out, then use a torx bit (the star-shaped bits) to take the metal bracket off of the back of the engine. Make sure that you don't use an allen wrench! I used an allen wrench with mine and that made it take months and months, because each line has a metal bracket holding it to the engine, and if you use an allen wrench, it won't fit in the torx shape, and you'll strip it out (I ended up taking a hacksaw blade to mine, because nothing would fit the screw after I stripped it out). Once you've got the metal bracket off of the back, then move to the front part of the nut kit, where the plastic hoses actually hook up to the lines that go to the fuel injectors. Remove the plastic holder (being very careful not to brake anything) and this should allow the two parts of the "nut kit" to be pulled out the backs of the hole. Put some grease on the new nut kit, and do the same process in reverse, being even more careful not to break anything.

    All the while you're doing this, you should be taking pictures to make sure that you rememer where everything goes. Also, be sure to clean out your engine once you're done. It should still work if you don't (mine did, and I didn't clean anything), but it'll run really rough until it burns away all of the excess gunk.

    Hope this helps!
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