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  • You guys are awesome

    So I had the "privilege" of joining another forum about F150 to try to get some research done on my uncles 1986 F150 5.0 EFI that he bought new and garage keeps. The thing is just amazing for being a 30 year old daily driver. I needed some help with early Ford fuel injection as I simply didn't remember the ins and outs of it.

    So long story short is after asking for help, I was be basically told I was an idiot and and didn't know what I was doing. On two separate posts. I was told I should get my facts straight before I post. Now I am asking for help, so if I knew everything I would be posting the questions.

    After reading that I thought to myself wow, that would never happen over a squarebirds, I pretty much have seen a few idiots wander through here and still they are helped way better than I was on the other Forum.

    So thanks for the help guys and great job. Happy to be a member here!!!

  • #2
    Ryan, you're always welcome here. As far as being an idiot, well, you're in good company because I don't know anyone who knows it all.

    BTW, we also 'do' injectors. What is your question? - Dave
    My latest project:
    CLICK HERE to see my custom hydraulic roller 390 FE build.

    "We've got to pause and ask ourselves: How much clean air do we need?"
    --Lee Iacocca


    • #3
      Message boards are only as good as the moderators who police them. This site is probably the best one I've seen to date.


      • #4
        This is a great forum and the members are very respectful of others.

        Thanks to all, that work hard to keep this site Great!

        Sedalia, Mo.
        CLICK HERE for Keith's web site


        • #5
          You guys are awesome

          Thank you for these comments. They are very much appreciated... To honor the memory of our founder, Alexander Sosiak, we have strived to keep this Forum operating as he established it, following his Rules Of Conduct. I can tell you this. Julie, his widow, and Marianne, his sister, are very pleased with the way we have continued to honor his memory by expanding and maintaining his Forum in the manner he would have greatly approved of. Marianne ~ My59Tbird stepped in shortly after his passing and continued handling the Detent Plate program for us. From time to time, as she has time from raising her family, you will see her logged onto the Forum. Should you have any questions for her regarding detent plates, or availability, you can click on the Members List, go to the letter M, then to the last page of M's, and you will find her user id listed there. Clicking on it, you can send her an email or a PM. I suggest the former, because you are more likely to get in contact with her quicker that way.
          Last edited by YellowRose; March 4th, 2016, 03:07 PM.

          Ray Clark - Squarebirds Administrator
          '59 Tbird "The Yellow Rose Of Texas" aka "Tweety Bird"
          "It's Hip To Be Square"
          Thunderbird Registry #33025 VTCI #11178

          Contact me via Private Message for my email address, or (Cell) 210-875-1411 (Home) 210-674-5781


          • #6
            sorry dave. My uncles truck has been around the block. Several mechanics have replaced endless parts. The emissions light is on and it runs like poo. Here is the symptoms.

            starts and kills 2x's in the morning, back fires during acceleration and hesitates. for the first 5mphs then runs fine, starts hot very poorly.

            actually I will copy and past my original post from the other forum. LOL I think I was pretty respectful. .

            here it is

            Good evening gentlemen, I am new here but a user of several other forums so I know new posts can be a pain from a first time poster, so sorry in advance.

            So here we go. My uncle had a 1986 F150 EFI. He bought it new and it is garage kept to this day. I am very knowledgeable fellow about new Fords, but this old one is kicking my but.

            First I have codes 12, 41, 25 and an emissions light is on.

            Second the truck runs like poop and is backfiring on acceleration.

            The list of parts he has changed is out of the box. It has a new distributor assembly, HP pump, tank switcher and new fuel tanks, new egr valve, position sensor, and evp solenoids. ( only part replaced by me so far ) and it did fix the egr code. It also has new IAC, TP and O2, which complicates the issues of some of the above codes.

            The fuel pressure is at 39 running, but I have noticed if it sits over night I have to cycle the key twice to get it to come up to 35ish. It starts and kills twice every morning on cold start then runs. ok-ish

            I have also sprayed down the intake to check for vacuum leaks. no difference.

            once the truck has accelerated past 10 mph it runs fine. If just hates the acceleration from a stop.

            The only modification is crane energizer cam during a rebuild about 2 years ago.

            The timing is set 10 with the spout disconnected. ( not sure if should be different with the cam, so I just set it to factory setting)

            So question is any ideas? I was going to go buy a new IAC to see if it clears code 12 and possibly a 20buck O2 again so I can do it myself to see if it effects the lean code. The knock sensor I am pretty sure will have to be a junkyard dog item as they are not available any where.

            Thanks in advance and I will be back shortly.



            • #7
              sorry. I was nailed for not posting the code definition and I did it again.

              code 12 can't control idle at high speed/RPM
              code 41 HO2S lean
              code 25 Knock sensor not detected

              the end result is this. This is a 1986 EFI 5.0 truck. I believe the super early EFI was very sensitive to exhaust leaks. This truck has one. I am thinking this is my main issue with its driveablity. We are ordering a set of headers for it.


              • #8
                Those are the early years of Ford EFI. I had an '85 TBird 5.0 that was a 2 barrel throttle body. As I recall in '86 they went to a multi-point, and yours is probably the same.

                I'm also a member of the allfordmustangs forum and they have a specific section for the 5.0L mustangs. You can probably find the information you need there. Here's the link:


                • #9
                  correct it is the first version of the mpi injection. lots of one year part on the 86 F150.


                  • #10
                    Originally posted by Ford351c594 View Post
                    ...once the truck has accelerated past 10 mph it runs fine. If just hates the acceleration from a stop.

                    The only modification is crane energizer cam during a rebuild about 2 years ago...
                    What duration cam did you buy, and why?

                    Most people want a little more out of their engine so they buy a 'street cam'. That's all well and good if you understand the consequences involved. They run better at higher rpm's than at idle because of the overlap for scavenging. The cam timing may also be retarded for better high end torque and performance.

                    As far as your sensors go, the oxygen sensor is not in the picture and it won't work until the temp is at 'normal'. During this time your EEC runs a 'canned program' for cold starts. All your sensors can be checked with a multimeter, including your injector inputs, idle air control, etc. There is no reason your fuel pressure should drop during idle.

                    If you have cylinders not firing, a IR gun will tell you quickly. Without actually seeing the engine, it's difficult for me to troubleshoot from this chair in Royal Oak, Michigan. - Dave
                    My latest project:
                    CLICK HERE to see my custom hydraulic roller 390 FE build.

                    "We've got to pause and ask ourselves: How much clean air do we need?"
                    --Lee Iacocca


                    • #11
                      it is a crane energizer. The engine was rebuilt about 60k miles ago by some one else so I don't know. I know it has ran fine for a long period of time. I put the truck in self test mode with an old NGS I had and it can control the idle so I don't think the IAC is an issue.

                      The fuel pressure issue is interesting. it has a new front tank and sender with low pressure pump. A new pressure regulator, and a new frame mounted high pressure pump( unique part to early Ford MPI). Also a new tank switcher. All done about 7 months ago by someone who said it would fix the issue.

                      This truck is giving me fits!!!!!!!!!!

                      The fact I don't know all of its history is just insane.

                      Some of the few things I have done are:

                      II replaced the EGR solenoids. I also replaced the egr position sensor to clear egr codes which did happen. The egr sensor was new as well at the time I replaced it. The solenoid was open and the position sensor was reading .97volts closed. I believe it is supposed to be approx. .6volts.

                      It also had TP codes, but it was adjusted wrong and I fixed that as well. Reading .81volts at idle now.

                      He told me he thinks they installed a new PCM as well. I found the receipt for that from O'Riely's in the glove box.. so yes.
                      Last edited by Ford351c594; March 7th, 2016, 12:15 PM.


                      • #12
                        I am not one who throws new parts at a problem because it complicates matters to no end. Sometimes it causes problems move to other areas, especially while troubleshooting.

                        I use sound troubleshooting techniques as I go through each section, looking for known results. For instance, you can change all the EGR parts you want but if carbon has blocked off exhaust gas flow, the system will simply not work. Conversely, if the EGR is stuck open, the engine leans out causing terrible idle. I look for ~0.5volts on the Throttle Position Sensor, then watch it go to 4.5 at Wide Open Throttle. Body grounding is also important.

                        Troubleshooting from this chair turns into a guessing game that is impossible to do. You need to understand each function and then test. For example, a good running EGR doesn't work at all until the car is RUNNING down the road in drive. You can check for vacuum leaks in the garage but that's only a partial story.

                        Watch this youtube video, all three parts: CLICK HERE
                        - Dave
                        My latest project:
                        CLICK HERE to see my custom hydraulic roller 390 FE build.

                        "We've got to pause and ask ourselves: How much clean air do we need?"
                        --Lee Iacocca


                        • #13
                          it was the fuel injectors. I believe from 86 to 89 ford used single pintal exposed fuel injectors. super common to failure. (left side)

                          I replaced them bosch 4 hole injectors that have the pintal protected from egr and pcv and it runs beautiful. flow matched set remanufactured only costed 149 bucks.
                          Attached Files


                          • #14
                            Glad you found the problem. Don't forget to change your fuel filter.
                            My latest project:
                            CLICK HERE to see my custom hydraulic roller 390 FE build.

                            "We've got to pause and ask ourselves: How much clean air do we need?"
                            --Lee Iacocca


                            • #15
                              Thanks for the update!