• If this is your first visit to the iboats.com Boating Forums, be sure to check out the FAQ. To post a question or comment, begin by signing up. To start viewing messages, select the forum that you want to visit from the selection below.


Announcement

Announcement Module
Collapse

Help Tip: If you have a question that has not been answered to your satisfaction in the archives, it is always best to start a new thread of your own. By starting your own thread, you will receive the maximum number of views by forum members.

Below are some additional forum policies in hopes of all iboats members will follow, Thank you.

1. Please do not reply to old topics or hijack existing topics. Old topics of a technical nature are like a library book, Please do not write in them.

2. Old topics should be considered archives and used for reference only. Please do not reply to them.

3. Do not take over someone else’s topic (aka hijack) with your own question, even if it is similar. If you have a question that has not been covered to your satisfaction in the archives, it is always best to start a new topic of your own.

4. If you have a question for the original poster (OP) and the topic is over 30 days old, send the OP a PM, he may not even visit the forums any longer, or may not notice your question in the old topic.

5. By starting your own topic, you will receive the maximum number of views by forum helpers that may not even notice your question when it’s posted at the end of someone else’s topic. And those answers will be specific to your particular issue.

6. Please do not post to topics that have been inactive for more than 3 months unless you are the original poster. We have very active forums and any topic that remains inactive for that long should be considered "dead". It is especially confusing when there is an entirely new question posted to an old topic.

7. Posting at the end of any topic is considered to be hijacking the original posters topic which in turn subjects the topic to be closed if it continues to happen thus not making it fair to the original poster in the future had for some reason he/she needed to return for additional information or provide an update of the problem solved which is always welcomed within a reasonable amount of time frame.

8. Please note that you should see a red banner pop up near the bottom of each inactive topic asking you not to reply to old topics. The Red banner will read: Please note this topic has been inactive for 90 days. For the best results, please start a new topic.

Thank you all in advance for doing your part in helping iboats run a smooth ship.

Additional forum rules linked below.
http://forums.iboats.com/forum-rules-guidelines-405/
See more
See less

Backfire through carb under load

Page Title Module
Move Remove Collapse
X
Conversation Detail Module
Collapse
  • Filter
  • Time
  • Show
Clear All
new posts


  • #76
    Re: Backfire through carb under load

    This weekend I am going to go through the checklist again. I have petronix ignitor ignition, no problem shifting. I am not sure if there is a shift assist module on that year, but I don't think so, when I shift there is no engine hesitation at idle.I will also do a compression test, but everything still seems rather suspect to me that the backfire only occurs as the secondarys open. I have never got it to backfire reving it with only the primaries opperating.Timing was good, advance was also workingpump is newlines are all clearvaccuum test was goodthanks all, hopefully when I get this running again I can proudly post the solution, this one has everyone I have talked to stumpped.

    Comment



    • #77
      Re: Backfire through carb under load

      the solution will be replacement carb mahoney... he he he trog100

      Comment



      • #78
        Re: Backfire through carb under load

        Damn trog, you're one ugly dude Mahoney, before you go and start spending more money check your spark. Should have a nice blue crisp color and a "snap"ing noise. Aldo
        Watch this space......................

        Comment



        • #79
          Re: Backfire through carb under load

          thanks Dunaruna, Ill add that to the list of double checks as well.

          Comment



          • #80
            Re: Backfire through carb under load

            Well, Im not going to read all the replies to find out what you've done, but did you check the small cam that lifts the secondary metering rods up when the secondaries are open? They can break and then the metering rods won't lift up when the secondaries open.
            Don S.

            sigpic

            Please, no PM's (Private Messages) regarding boat/engine problems.
            That is what the forums are for.
            Only forum/moderator issues will be answered in PM's.

            Comment



            • #81
              Re: Backfire through carb under load

              Yup Don, checked that. That cam is only operated when the actual airchokes are open on top(and all seems fine), which I couldn't check for sure because I had the flame arrestor on. Didn't want to be to careless regardless of how frustrated I am gettingPlugs are always black when I take them out, not wet, just black. This should indicate a rich condition, which got me thinking I might want to relook at my timing.I should probably start a new post for it, but here it is. I have always noticed when I am adjusting timing that if the engine is running at ~700 rpm and I set the timing by rotating the distributor to where it is supposed to be to make the timing mark match up to 8 deg BTD, I can turn the distributor and it makes more RPM and the engine runs smoother.I think I might do this next time and keep adjusting then backing off throttle till I am back at my idel rmp range and check timing again. Not sure if this would cause the backfire through the carb I am experiencing, but I am running out of options.

              Comment



              • #82
                Re: Backfire through carb under load

                You can simply advance or retard your timing by 2 to 3 degrees and see what happens. If it gets better suspect balancer slip, wrong balancer, or wrong timing cover.
                Of those who receive good advice, only the wise will profit from it.

                If you need it....Get it
                If you want it....Wait
                If you have it....Flaunt it


                sigpic

                Comment



                • #83
                  Re: Backfire through carb under load

                  Well Mahoney amazing I tracked you down here,s a site you should check for your acc pump and so on adjustment's click on in carb sectionRochester Quad Manual M4Mc +++++get ready for your neck exercises Ben There http://www.oldcarmanual.com/
                  You forget you don't remember!
                  Friends are family we choose for ourselfs
                  Ifin YOU KNOW it goes....if not it doesn't
                  Transom Repair http://www.shareaproject.com/pages/i...i,1437,00.html

                  Comment



                  • #84
                    Re: Backfire through carb under load

                    Haha, thanks again dolluper(ben there)I replied and thanked you in your other post. As you can see I have been hitting everyone up for suggestions. I think with everyone pitching in like they have we will get this thing licked.

                    Comment



                    • #85
                      Re: Backfire through carb under load

                      Got a question for you when you got this boat did it have AC s/plugs in it if so what # were they if not post the # and kind ,if AC post that #
                      You forget you don't remember!
                      Friends are family we choose for ourselfs
                      Ifin YOU KNOW it goes....if not it doesn't
                      Transom Repair http://www.shareaproject.com/pages/i...i,1437,00.html

                      Comment



                      • #86
                        Re: Backfire through carb under load

                        I can check on that, I know now I have ngk plugs from cross referencing the old ones at Schucks. I still have the old plugs so I will check them out when I get home.

                        Comment



                        • #87
                          Re: Backfire through carb under load

                          Post AC #'s if you can I have an attack plan
                          You forget you don't remember!
                          Friends are family we choose for ourselfs
                          Ifin YOU KNOW it goes....if not it doesn't
                          Transom Repair http://www.shareaproject.com/pages/i...i,1437,00.html

                          Comment



                          • #88
                            Re: Backfire through carb under load

                            I also found some other stuff I think I overlooked. There was a wire going to the distributor when I had my original point system that I double checked with pertronix. I had it not attached to anything, and it needs to go on the + terminal on the coil. That should be fine now(could definitely contribute to advance timing problems I guess)Also reading through the manual you sent me on the carb, I am questioning weather I have the needle valve plunger retaining clip hooked up correctly. It says it need to be connected on the center of the float arm, but it also notes it SHOULD NOT be connected to the 2 holes on top of the float arm. Well with the new float I got in the rebuild kit, these are the only places to connect it, so I am going to get the old float and double check this.

                            Comment



                            • #89
                              Re: Backfire through carb under load

                              That was one of my taughts it is tricky the first time you do one but you will never forget it now the plugs should sort out any if any timming problems it will ID the motor better to get the spec's, since in a boat you will time it as if it was a standard [gearshift] car not autos more RPM and some motors less degree's, by the way if I were you I would stick to AC's
                              You forget you don't remember!
                              Friends are family we choose for ourselfs
                              Ifin YOU KNOW it goes....if not it doesn't
                              Transom Repair http://www.shareaproject.com/pages/i...i,1437,00.html

                              Comment



                              • #90
                                Re: Backfire through carb under load

                                i would have to agree that the carb is not the problem. i have the same problem with my '79 searay with 305. i have discovered the hard way (bought a new carb) that it is a miss that shows up under load only. it runs fine in driveway except for barely noticeable miss, but under load it misses and backfires. i have narrowed problem down to cam, lifters or valve problem----not a fuel issue

                                Comment

                                Working...
                                X