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please advise about injectors and fuel rail replacement

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by buckmeister2, Jan 27, 2013.

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  1. buckmeister2

    buckmeister2 New Member 100 Posts

    hey, guys,

    i'm getting ready to buy injectors for my '01 5.3 with 168K on it. i doubt they have ever been replaced. i don't see much difference in injector prices from online sources, and wondering if any of you have a link to a place with good prices. what is your advice about reman vs. new? my truck is basically stock, and i will not be doing any seriious engine mods, so stock injectors will be fine. also, is there a "wear factor" to fuel rails? what would justify replacing them while doing the injector replacement?

    thanks for your help.

    jim, las vegas
    buckmeister2
  2. Pikey

    Pikey Moderator Staff Member 1000 Posts 100 Posts

    You can buy new AC delco injectors on Amazon cheaper than what most stores charge for a reman. It helps is you go to your local dealer with your vin and get the correct part number. Then search for it on amazon.
  3. bazar01

    bazar01 New Member 100 Posts

    I would like to know why you are replacing injectors and fuel rails? I have 170k miles on original injectors and don't see any reason to replace them. So far, I only replaced the fuel pump and fuel pressure regulator and the engine is still running very strong and still gets 18-20 mpg.
  4. TRPLXL2

    TRPLXL2 New Member Platinum Contributor 1000 Posts 100 Posts

    I think the 01' style fuel rail has the fuel regulator built into the rail, It is not sold seperately. As far as the injectors, are they clogged or what?? I found a good how to on cleaning injectors on a BMW forum, I used CRC non chlorinated brake cleaner and soaked and then blew them out with compressed air. I was amazed at how much crap came out of them, I did a set of injectors with 84,000 miles and a set with over 140,000 and I'm still running both sets with no problems. I checked the injector flow before cleaning, and they were around 7.9lbs, after cleaning they were back at 10lbs.

    If you buy new one's they might not come with new o-rings, if not then you should get the injector rebuild kit x8 ($15.00).
  5. buckmeister2

    buckmeister2 New Member 100 Posts

    I do not know they are bad, but the truck was badly neglected before I got it just recently. I don't know the history of what was done and not done. It runs fair, but only gets 13mpg in town, with me being as light on the throttle as possible, and coasting at every opportunity. Idle is 500 rpm. I did plan to clean them out with cleaner and compressed air, but do not know how to check the flow rate. I figured I would clean them up and put them back to see if there is a diff, but I asked the question as a way to prep for the worst. How do I reliably measure air flow? I am interested in seeing if there is improvement after cleaning. I am aware of the need for o-rings, and appreciate your comments. Thanks for the advice...let me know if there is an easy "home" way to measure the flow rate.
  6. TRPLXL2

    TRPLXL2 New Member Platinum Contributor 1000 Posts 100 Posts

    Do you have a diagnostic reader such as HPtuners or something that does bidirectional scanning? I use an old Snap on MT2500 that I got for $150.00, It gives me the live readouts for the injectors while the truck is running. I wrote down all the values of each injector, then I cleaned them and reinstalled and checked again and that's how I found out that it actually worked.

    I also went to the Chevy dealer to get a price of bench flow checking, they wanted to charge $150.00 to flow check them. I would not pay that, but it is an option.
  7. shibby2oo8

    shibby2oo8 New Member 100 Posts

    When I was in the shop this is what we did, disconnect injectors from manifold and place little measuring cups under, connect fuel pressure gauge, charge the system by keying up 2-3 times so starting pressure is the same. Now we had a little OTC box the plugged into the injector and pulsed them for selectable amout of time, you can use a scanner or something to power the injector but the on time is important. Then work through all of the injectors and record volume from the cups and pressure drop from the gauge. Badda boom your done. Also measure resistance of the injector with an ohm meter because the resistance changes how the open. Sounds difficult but not really if you have a way to pulse them. I was just looking at ebay for those OTC pulsers and they are $138, if I find oe cheaper I will let you guys know.
  8. buckmeister2

    buckmeister2 New Member 100 Posts

    thanks for the answer, and idea. I appreciate. Honestly, if I had the tool, I would likely check them. Wish you could pick that stuff up cheap, which is exactly why i asked the question I did. If you have to pay $150 to $200 just to have someone tell you there is a bad injector(s), well....you might as well just replace them. With 170K on the clock, and poor maintenance prior to me, it can't be a bad idea to spend the bucks and know they are okay. I've already purchased plugs, wires, etc, and would like to know if anyone has a line on a good price for inj's. thanks for your help, though.
    jim

    - - - Updated - - -

    man, that is a cool idea. i have been wondering what types of pressurized systems I could hook up to each injector to get the same result. What if I could pressurize a small tank to "x" pounds, then hook an air line into the injector. Open the air valve and time how long it takes to drop pressure to "y" pounds....would that also indicate flow discrepancies?

    jim
  9. shibby2oo8

    shibby2oo8 New Member 100 Posts

    You still run into powering the injector for the right time problem though.
  10. buckmeister2

    buckmeister2 New Member 100 Posts

    for accuracy, you are correct. what i am looking for with such a test, though, is consistency and comparison. if injector 1 takes 1.3 seconds to drop "x" pounds, and injector 2 takes .7 seconds (just as an example), then I can conclude that #1 is a bigger problem than #2. Also, getting all the times recorded, then going through a complete cleaning process, I think one could compare improvement, and establish some kind of baseline. Likewise, after cleaning, if an injector shows a loss of pressure when closed, I can deduce it may be a problem (though air molecules are much smaller than fuel molecules, so the system would then be used with fuel to determine if there is leakdown). I know it is crude when compared to instruments costing $190 to $1900, but should give some general info to me. If not, i will just replace them all....not that expensive.
    thanks for your comment. jim

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