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Fuel injector stuck open?

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    #1

    Fuel injector stuck open?

    So hey guys i got a 1990 grand marquis and its been misfiring on #8. I checked the codes while running and it gave me the usual egr and the thermal stuff that goes behind the heads which i blocked off when we rebuilt the block. Pulled the spark plug and its smells like raw gas and its black as sin. I checked the wires and even switched the wires and plugs from the other cylinders and it still misfires. Do y'all think the injector could be stuck open or maybe a burnt valve?

    Sent from my LG-LS997 using Tapatalk
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    #2
    Sounds like possible stuck injector, but if it had no spark you'd get pretty nearly the same thing. If you've swapped plugs and wires thats probably not it tho. Fuel pressure test would help confirm. If it leaks down fairly quick its going someplace. A compression test wouldn't be a terrible idea either, if its got none it won't burn the fuel off.
    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC grandpa spec white and cranberry

    1984 Lincoln Continental TurboDiesel - rolls coal

    Originally posted by phayzer5
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

    Comment

      #3
      I also forgot to mention it only misfires at idle and when coasting or slowing down to a stop. At highway speeds it runs perfect

      Sent from my LG-LS997 using Tapatalk

      Comment

        #4
        As far as checking the injector, you could check with a noid light to ensure you have an injector pulse still. After that I would swap in a knowing good injector or swap around injectors and see if the issue follows or remains on your trouble cylinder.

        Like Gadget said run it through a compression test.

        It was mentioned to me a rudimentary way to check for a possible burnt valve condition was to hold a piece of paper about a half inch away from the tailpipe. If it gets sucked in and blown out repetitively, there's a chance something is wrong engine side. I've come to the consensus my '87 burned an exhaust valve and I experienced similar symptoms, but obviously in your case don't jump to conclusions just yet. I ran through quite a bit of asking questions here and troubleshooting before arriving where I did.

        When I ran a compression test I got roughly 10 PSI out of the suspect cylinder. Like yours has done, mine misses at idle or deceleration, but cruising along you can't really tell there's an issue. I did note a dramatic loss of fuel economy, however, going from roughly 15-17 city to 9-11 city. Highway mileage seemed generally unchanged and continued managing 19-21.


        My Cars:
        -1964 Comet 202 (116K Miles) - Long Term Project
        -1979 Ford LTD Landau (38K Miles) - New Cruiser        ​
        -1986 Dodge D-150 Royale SE (112K Miles) - Slowly Getting Put Back Together
        -1987 Grand Marquis Colony Park LS (343K Miles) - April 2017 + September 2019 POTM Winner
        -1997 Grand Marquis LS (244K Miles) - March 2015 + January 2019 POTM Winner - Sold (05/2011 - 07/2024)

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          #5
          Thanks for the advice guys. Ill go check it next week when im off since i have her parked at my parents olace and it takes about an hour to get there. Will keep you all posted

          Sent from my LG-LS997 using Tapatalk

          Comment

            #6
            If you are experiencing a leaking fuel injector you would have hydrostatic lockup, I would think combustion chamber blowby meaning burnt valve.

            Comment

              #7
              They can be stuck open and not have hydro lock. I had one on the old 89 where the pintel was obviously stuck open.
              03 Marauder DPB, HS, 6disk, Organizer Mods> LED's in & Out, M&Z rear control arms, Oil deflector, U-Haul Trans Pan, Blue Fuzzy Dice
              02 SL500 Silver Arrow
              08 TC Signature Limited, HID's Mods>06 Mustang Bullet Rims 235/55-17 Z rated BFG G-Force Comp-2 A/S Plus, Addco 1" rear Sway, Posi Carrier, Compustar Remote Start, floor liners, trunk organizer, Two part Sun Visors, B&M Trans drain Plug, Winter=05 Mustang GT rims, Nokian Hakkapeliitta R-2 235/55-17
              12 Escape Limited V6 AWD, 225/65R17 Vredestein Quatrac Pro, Winter 235/70-16 Conti Viking Contact7 Mods>Beamtech LED headlight bulbs, Husky floor liners

              Comment

                #8
                What exactly is hydrostatic lockup? Never heard of it, ive only heard of hydrolocked

                Sent from my LG-LS997 using Tapatalk

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                  #9
                  Same thing. The injector could be slightly leaky, not enough to fill the cylinder but enough to run too rich at idle. Internally its just a needle valve and a seat. Open one millions of times and both can wear enough that its an imperfect seal.
                  86 Lincoln Town Car (Galactica).
                  5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                  91 Lincoln Mark VII LSC grandpa spec white and cranberry

                  1984 Lincoln Continental TurboDiesel - rolls coal

                  Originally posted by phayzer5
                  I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

                  Comment

                    #10
                    Makes sense. And if it helps any the motor makes a popping sound at idle and i hear hissing for a second or two when i turn it off

                    Sent from my LG-LS997 using Tapatalk

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                      #11
                      Alright so i did a compression test on #8 and it came out to 160. So def not a burnt valve. I am going to get a whole set of new injectors. Should i go 19 or 24lb injectors?

                      Sent from my LG-LS997 using Tapatalk

                      Comment

                        #12
                        Unless you’re running a tune or a HO/Explorer swap at this moment, running a larger injector will not help you and would likely run worse. Stick with the 14 LBS injectors if you’re still stock. I got a set of eight remanned ones off of eBay. Avoid the Chinesium ones, they’re junk! I found that one out the hard way.

                        You may see listings for the four hole and single single pintle type injectors. Single pintle are OE, and four hole are technically improved design. The four hole ones supposedly have better atomization ability compared to the single pintle types, but I don’t know how much better it would be on our engines. I just stuck with single pintle ones when I ordered my remanned ones because they were cheaper.


                        My Cars:
                        -1964 Comet 202 (116K Miles) - Long Term Project
                        -1979 Ford LTD Landau (38K Miles) - New Cruiser                        ​
                        -1986 Dodge D-150 Royale SE (112K Miles) - Slowly Getting Put Back Together
                        -1987 Grand Marquis Colony Park LS (343K Miles) - April 2017 + September 2019 POTM Winner
                        -1997 Grand Marquis LS (244K Miles) - March 2015 + January 2019 POTM Winner - Sold (05/2011 - 07/2024)

                        Comment

                          #13
                          yes, stock 14# injectors for the stock engine. 19 for an HO unless the ECM has been tuned otherwise.
                          86 Lincoln Town Car (Galactica).
                          5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                          91 Lincoln Mark VII LSC grandpa spec white and cranberry

                          1984 Lincoln Continental TurboDiesel - rolls coal

                          Originally posted by phayzer5
                          I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

                          Comment

                            #14
                            OH yeah, couldn't you check fuel pressure once you flip the key off? I'm not sure but I thought these hold pressure for awhile so if you've got a leaking injector, you'll see pressure bleed off. Just my arm chair quarterback idea.

                            Like K wolf said about the injectors, I think I would just run OE single pintle.
                            1985 LTD Crown Victoria - SOLD
                            1988 Town Car Signature - Current Party Barge

                            Comment

                              #15
                              Yes, definitely check fuel pressure. I bought a tester kit at harbor freight for pretty cheap and it works! Easiest place to start.

                              Comment

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