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Hard starting, won't idle, won't rev - 2000 Grand Marquis

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    #16
    I'd be changing the fuel filter. You might have the pressure but not the volume. Who knows what that old fuel sludged up in the existing filter, or even if the existing filter was on the verge of causing problems even with good fuel. Not to mention any foreign debris that may have been introduced by the transfer vessels.

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      #17
      Having worked at a gas station in my youth, "there's nothing as expensive as free gas".
      Even diluted, if it's sludge and varnish then it's not going to burn as well. The stuff in the tank is exposed to air; the stuff in the lines is not. So the donor car will run well on startup, but maybe not much longer. Once the gas is mixed from running the pump/return line, 20 years of condensation and sediment is stirred up in there.
      Drain it out and use it for a bonfire. On a carb'ed car with no return line, might be able to run a few miles before it conks out.

      On OP's car: Drain as much as you can. You've added gas to it and the gunk is on the bottom, so not sure of the best way to get it out without getting a lot of the gas you just added. Water and sediment sink to the bottom (fuel pump/pump sock) but if the sock is gunked up running it out with the pump means you'll be dropping the tank next.

      If it was my car, I'd drop the tank, empty it, scrub it with a rag, new fuel pump sock, new fuel filter. A can of injector cleaner and 4 gallons of fresh gas (4 gallons in a 5 gallon can so there's room to pull it all out if I need to drop the tank again: never top off the tank when dealing with fuel issues, or at least know you have a big enough container to put it all in before you start!). Then get back to basics on diagnosing the start and run.

      A long way back, as a dumb kid at the aforementioned gas station, I was doing an oil change. A kid came in with his grandad's Oldsmobile diesel. A Cutlass, I think, but it was a looooong time ago. He puts in 10 bucks, which was probably about 10 gallons back in those days. Then realizes: this "diesel" has been replaced with a gasoline engine, the only diesel part left on it is the lettering on the trunk lid.

      So we siphon out the tank and get him filled back up with gasoline. There's about 12 gallons of mostly diesel in jugs in the shop. We've got a waste oil burner and it's been cold so we're almost out of oil, I know we can burn diesel in it. I dump it into the basically empty waste oil tank and fire it up. About 10 minutes later there's a series of bangs but everything seems okay. More smoke than usual from the chimney pipe but it's running so after a few minutes I figure everything is okay.

      Next time we go to run the WO burner, it won't light. Apparently there wasn't enough gas to do serious damage, but when it fired up it damaged the igniters in the furnace. Heater tech told us it could have done serious damage if there was much more gas in there. Got a reaming from the boss (but learned a lot about setting up oil burners).

      Plenty of cars and motorcycles came to us with fuel systems gummed up from free gas. "I sold the boat with a 2 stroke, realized I had a couple gallons left, so I just dumped it in the truck..." "It's been in the garage for a decade so I figured I should just use it up..." "We were having that old junker towed out of the back yard, and thought I could save the gas from it..." "It fired right up, but as soon as I got halfway around the block it stopped dead..."

      So, yeah. Nothing so expensive as free gas. Maybe in a mower or weed whacker where you can turn it upside down and shake it out, but not in a truck. Heck, I got a load of bad gas from a gas station in 2004 in my F150 and I couldn't use the rear tank for years. Clogged the pump and tank selector valve and stupid me kept trying to burn it in batches after separating out the water. Spent a lot more in filters than I saved in gas. Should have just capped it off, or dropped everything and worked the system over from back to front, but I'm not that great at taking my own advice (it ran great on the front tank, so if I just use the rear tank a few minutes at a time to use that gas up...right??)
      Last edited by bgreywolf; 12-16-2020, 03:38 AM.

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        #18
        Sorry I missed the part about fuel pressure in the OP.
        Does the the fuel pressure rise with RPM?
        ..

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          #19
          I just re-read my post and I apologize if I was a bit cranky. Free gas (and multiple other instances of "completely change the design to save 5 bucks because someone gave me a 3 buck part") is one of my pet peeves; usually because I have to help people fix it, and because I warned them before they did it, then they object to putting things back to the way they were when they worked, and then they do it again as soon as I'm gone.

          OP, I hope that it's not going to require dropping the tank. My most recent go-round was a friend who used the in-tank pump from his parts van instead of a $30 new one...and then immediately put over 25 gallons in, only to have the old pump seize up that afternoon because it had been sitting in a tank full of old gunky gas for over a decade. Again, sorry for the rough reply above.

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            #20
            you can always tell who has dealt with things too many times by their reply
            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


              #21
              Hi.
              This car is still broken.

              If I remember correctly the following have changed since the last updates in this thread:
              -tank was drained and new filter was installed.
              -I observed that the fuel flow seemed to be kind of poor (tank drained using the in-tank pump) but it maintains required pressure with engine running, so that isn't likely the problem
              -I believe the balance of the injectors got changed
              -the cats were fully cut betw/ upstream and downstream, and the upstreams were gutted. current situation is functionally like open headers.
              -a believed-known-good MAF off a 99 was swapped on

              No difference in behaviour at all. If the MAF is connected, it will not respond to throttle input. If the MAF is not connected, it will lazily respond to throttle input. Regardless of MAF, it runs like ass.

              Current state of things: https://youtu.be/oo2FN89rt34

              Got my hands on a 99 PCM however it's from a Mercury with no keys, so it's a brick (PATS). Trying to sort out if there's a way around that perhaps using FORScan but would rather just find a P71 PCM. One has been offered but it has a tune that makes it not usable as an on-road PCM for our needs plus it isn't local, so we're looking at other options before taking that offer.

              This is an astonishingly tenacious problem, given these are one of the most bulletproof engines in one of the most bulletproof cars of all time that can rack up tons of mileage in abusive conditions with no more than minor issues. Just sort of ironic is all...the only car this person (friend) has ever encountered that he can't make work, and it's one of the most generally trouble-free cars ever made.

              Current driver: Ranger
              Panthers: 83 GM 2dr | 84 TC | 85 CS
              | 88 TC | 91 GM
              Not Panthers: 85 Ranger | Ranger trailer | 91 Acclaim | 05 Focus
              Gone: 97 CV | 83 TC | 04 Focus | 86 GM
              | Junkyards

              Comment


                #22
                I am by no means literate with the mod motor. I just got curious with Google as I am sure you have, and here's what the great Google says to try.

                1.) This person is having a very similar problem. Unfortunately it is not reported if it fixed the issue. But gives you a few more things to try with the PCV and also the IAC possibility. https://www.ford-trucks.com/forums/1...f-testing.html

                2.) Be very sure there are no vacuum leaks. My 6.8 will barely run, if at all, if a vacuum hose is unplugged, which is very different from my experience with other engines.

                3.) Verify function of air and coolant temperature sensors.
                1990 Country Squire - weekend cruiser, next project
                1988 Crown Vic LTD Wagon - waiting in the wings

                GMN Box Panther History
                Box Panther Horsepower and Torque Ratings
                Box Panther Production Numbers

                Comment


                  #23
                  +1 Check the temp sensors. They still use the same resistance curve as mentioned on the old fuel injection site... http://www.grandmarq.net/oldfuelinjection/page28.html
                  The MAF temp sensor (if 6 wire) should read the same as the ACT... or just test the ACT that's in the air filter box if 4 wire MAF. http://www.grandmarq.net/oldfuelinjection/page29.html

                  I've also had to replace the pigtails to those sensors on a couple of cars due to the wires going bad at the final bend into the connector. If you have any ability to pull live data from the OBD-II port on temps, that could be another way to test those. Cold start should match ambient temps pretty much.

                  Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
                  rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
                  Originally posted by gadget73
                  ... and it should all work like magic and unicorns and stuff.
                  Originally posted by dmccaig
                  Overhead, some poor bastards are flying in airplanes.

                  Comment


                    #24
                    Oh yeah... check the IAC and EGR for proper function. I've had to replace the IAC on EVERYTHING at some point other than the 2000. But it's not got a lot of miles on it either. And if the EGR isn't closing properly, it'll run like ass.

                    Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
                    rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
                    Originally posted by gadget73
                    ... and it should all work like magic and unicorns and stuff.
                    Originally posted by dmccaig
                    Overhead, some poor bastards are flying in airplanes.

                    Comment


                      #25
                      Due to time passage, we did not follow the above in sequence...your inputs are appreciated regardless. He called me and asked if I wanted to revisit this car's problems.

                      He put a sensor on it. It is unclear to me if it was the crank or cam position sensor. I thought we were going for crank but what he described to me sure sounded more like the cam sensor, now that I think about it.

                      I have a laptop with FORScan now, so I let him play with the datastream and see what he could get from it. He noted nothing about the IAC or EGR indicating a failure, but there is an interesting behaviour that if you lean into the accelerator pedal, the IAC opens. We have no idea if that's an as-designed part of how the PCM runs the engine, but we did observe it, consistently.

                      It was not possible to do the KOER test as the test self-exits if the MAF is out of range, and the car can't run with the MAF connected, so that's out.

                      The fact that the PCM continues to be unable to detect misfires, despite every single 'fire' being a 'miss', makes us continue to distrust the computer being able to run the engine, and buddy is now actively on the hunt for P71 PCM as a diagnostic item (it should be possible to find one locally)

                      I pushed him about the vacuum leaks he is positive it doesn't have, but I'm going to keep pushing. This is a NPI engine with a PI intake and he did have issues getting it to seal initially (I don't recall or inherently understand exactly what they were), so I am very suspicious of that.

                      More to come. The temp sensors definitely need to be verified. I do however have a hard time believing that any one bad input could make it run the way it does. It runs like the computer is for an engine of the wrong displacement and quantity of cylinders.

                      Also, so it has been said: FORScan (the full one) does not offer PATS programming options for a '00 Grand Marquis. It must be a vehicle application they never built out that functionality for.

                      Current driver: Ranger
                      Panthers: 83 GM 2dr | 84 TC | 85 CS
                      | 88 TC | 91 GM
                      Not Panthers: 85 Ranger | Ranger trailer | 91 Acclaim | 05 Focus
                      Gone: 97 CV | 83 TC | 04 Focus | 86 GM
                      | Junkyards

                      Comment


                        #26
                        I think iac open on throttle open is normal. It keeps the engine from stalling when the throttle is slammed shut, and the PCM can roll back the air as it sees fit in order to bring it back down to normal idle speed.

                        The crank sensor is what the engine uses to drive ignition and determine engine speed, which is also how it detects misfire. If thats not reading correctly you'll get funny misfire response. Should be able to see output from the CPS in the form of engine RPM or something. If thats glitchy or wrong that should tell you something.
                        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


                          #27
                          2000 would require the Ford dealer programming tool to program PATS. If you have one master key (original key), you can program other keys though. Without original keys, Ford dealer only from what I know. I think this involves 98-02 models. I'm probably wrong on the years.

                          Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
                          rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
                          Originally posted by gadget73
                          ... and it should all work like magic and unicorns and stuff.
                          Originally posted by dmccaig
                          Overhead, some poor bastards are flying in airplanes.

                          Comment


                            #28
                            I’m suspicious of the intake setup now. If he didn’t rtv the water passages at the front he could be leaking coolant into a runner. He also could be using the wrong gaskets. I believe the pi gaskets need to be used with a pi intake on npi heads.

                            As said iac thing is normal.


                            Sent from my iPhone using Tapatalk

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                              #29
                              Well, OK, so...things have happened.

                              Buddy broke down and bought a whole second 2000 in running condition (too rusty to use as a driver for more than like, a season at this point).

                              Because it has been a nagging possibility we keep coming back to, we swapped the PCM (along with PATS module and lock cylinder so as not to anger the PATS gods). There was fundamentally no change. So, seemingly not that.

                              We pulled the EGR valve and verified that it operates correctly and is not full of carbon. Checked out OK.

                              He cobbled together a solution to connect his compression gauge to this thing and found it has zero compression on the front two cylinders on the driver side (#5 and #6) but is otherwise healthy everywhere else. Bingo, we have our problem. We do not know the cause, but we know the problem.

                              It is not impossible that a fuelling issue did originally start this snowball, but it does seem like a long jump from bad gas to melted pistons or whatever.

                              It's going to get the good engine from the other car put in and then a post-mortem teardown to figure out what went wrong. He scoped it and says the pistons don't look great but nothing obvious enough, so it'll get opened up eventually.
                              Last edited by kishy; 10-27-2021, 03:42 PM.

                              Current driver: Ranger
                              Panthers: 83 GM 2dr | 84 TC | 85 CS
                              | 88 TC | 91 GM
                              Not Panthers: 85 Ranger | Ranger trailer | 91 Acclaim | 05 Focus
                              Gone: 97 CV | 83 TC | 04 Focus | 86 GM
                              | Junkyards

                              Comment


                                #30
                                Failing or partially clogged injectors could make the cylinders go lean. Running lean enough for a while will burn up the valves leading to a loss of compression.
                                Initial rough running could've been caused by running lean until the exhaust valves burnt up and caused poor compression, leading to more running problems.

                                That's just a guess.
                                1985 Mercury Grand Marquis LS, "Maisa"
                                1995 Chevrolet Caprice Classic STW, "Sally"

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