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Help from the carb gods out here please?-gctid381525

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    Help from the carb gods out here please?-gctid381525

    On my 87 2555, running a OMC 350 and cobra OD. Rochester 4 bbl marine carb. Starting is very difficult the FIRST time. Takes maybe 5 minutes of 15 second start attempts and 45 second cool downs on the starter (dont want to burn out the starter). Finally will start up. After that runs perfectly, good acceleration. Shut it down, turn the key and immediately starts right up. Even after letting it sit for 4-5 hours, turn the key and starts right up. Let it sit overnight, then im back to hard starting. Any thoughts on this? The thermal choke seems to be working properly on the carb and when I pump the throttle, I see fuel squirt intot he carbs.

    Boat has new plugs, wires, points, cap, fresh fuel, new fuel lines, new water sep.

    #2
    unixdood wrote:
    On my 87 2555, running a OMC 350 and cobra OD. Rochester 4 bbl marine carb. Starting is very difficult the FIRST time. Takes maybe 5 minutes of 15 second start attempts and 45 second cool downs on the starter (dont want to burn out the starter). Finally will start up. After that runs perfectly, good acceleration. Shut it down, turn the key and immediately starts right up. Even after letting it sit for 4-5 hours, turn the key and starts right up. Let it sit overnight, then im back to hard starting. Any thoughts on this? The thermal choke seems to be working properly on the carb and when I pump the throttle, I see fuel squirt intot he carbs.

    Boat has new plugs, wires, points, cap, fresh fuel, new fuel lines, new water sep.
    I'm not fully familiar with Marine version of Rochester carb, but the 'old quadrajet carbs" had a "soft plug" in the base plate that was prone to corrosion, there was a kit for it, drill hole, screw in sheet metal screw, pull screw/plug out... install brass plug w/neoprene o-ring. This was to cure hard starting issues.

    I have "vintage" mustang with Edelbrock carb, after sitting for months, it needs a prime (turn over numerous times, pause, pump gas pedal "vigorously", then turn over.... the third time is usally the charm!

    Comment


      #3
      Suggestions:

      If you are coming up on a possible starter motor replacement, go with one of the HTGR/PMGR motors. Cranking speed will be increased some, and battery load will be reduced some.

      Along the same lines as Cliff, the Q-jets can leak if the original build used epoxy to seal several of the manufacturing machine ports. Or perhaps the plugs that Cliff mentioned.

      When/if they do, the fuel bowl may drain off if not used for a week or so, so it must refill during cranking.

      The cure will be a fix to these leaking ports.

      An electric fuel pump, with a momentary over-ride switch, provides a rather temporary fix to this problem.

      This style fuel pump requires the low oil pressure shut down feature.... but the over-ride is easy to add.

      Edit:

      5.8L Ford HTGR/PMGR



      OEM non-gear reduction.


      Rick E. Gresham, Oregon
      2850 Bounty Sedan Flybridge model
      Twin 280 HP 5.7's w/ Closed Cooling
      Volvo Penta DuoProp Drives
      Kohler 4 CZ Gen Set

      Comment


        #4
        Thanks for the replies. i replaced the starter last season and that cranks much faster than the origional OEM type starter that was in it. I will check for leaky areas as suggested.

        Thanks

        Comment


          #5
          cliffm wrote:
          I have "vintage" mustang with Edelbrock carb, after sitting for months, it needs a prime (turn over numerous times, pause, pump gas pedal "vigorously", then turn over.... the third time is usally the charm!
          That sounds like exactly whats happening with my carb (no gas pedal though LOL)

          Comment


            #6
            Q-jets have a nasty habit of the float bowls drying out. It seems really common. My Merc 260 (Rochester) is the same as yours. I just crank it enough to get fuel there, and then she runs fine. I do it in pulses so as to not overheat the starter. It doesn't take 5 minutes though.

            You may want to review whether your fuel pump is dying. This will increase the amount of time it takes to get fuel there.

            Also, it should start right up if it sits overnight. What I mentioned above is for long duration (a week, say) or more.

            If you ran it yesterday, and it's tough to start today, look into the plugs as mentioned above. If it hasn't been rebuilt in a while, now's your excuse!

            In any case, definitely check the operation of the choke.

            Chay

            Comment


              #7
              Believe this or not..... but in this long cranking scenario, you WILL shorten starter motor life, and you WILL cycle your cranking battery more so than if the engine was quick firing.

              Once this week... antoher next week...... perhaps two the following weeks and with more to follow.

              These all add up to a reduced life span!

              .
              Rick E. Gresham, Oregon
              2850 Bounty Sedan Flybridge model
              Twin 280 HP 5.7's w/ Closed Cooling
              Volvo Penta DuoProp Drives
              Kohler 4 CZ Gen Set

              Comment


                #8
                Not to step on any body's toe's, but when using o-ring's or gasket material around fuel you want buna/nitrile, not neoprene, Neoprene is fuel & oil resistant, Buna is rated excellant,

                Comment


                  #9
                  Also a quick spray of starting fluid works wonders.

                  Comment


                    #10
                    I dont really like the starter fluid idea. a few years back i had a carb BURP up flames and ever since, never use starter fluid. I need to get to the main problem. I will be pulling the carb on Saturday and checking for that possible leaky screw that drains the bowl. And ya. I know you all cant stress enough NOT to overheat the starter by over cranking. Thats great advice and i follow that advice. Had my share of burning out starters in my early days of boating.

                    Comment


                      #11
                      Ether is not necessarily safe nor good to use in our gassers. Remember, you're not having compression issues, you're having NO FUEL issues.

                      A safer method may be to use a chemical squeeze bottle and fuel.



                      You can fill the float bowl directly through the vent tube while the engine is OFF, and not pose any danger to yourself or your engine.

                      Once the fuel bowl is near full, it would be as though you just turned the engine off, and all is ready to fire back up.

                      There are some starting fluids that contain only 50% Ether, if interested.

                      .
                      Rick E. Gresham, Oregon
                      2850 Bounty Sedan Flybridge model
                      Twin 280 HP 5.7's w/ Closed Cooling
                      Volvo Penta DuoProp Drives
                      Kohler 4 CZ Gen Set

                      Comment


                        #12
                        Good info to know Rick! THANKS!

                        Comment


                          #13
                          yeah I was about to suggest that. I used the squirt bottle (nice picture as always Rick) for my spring start up and was pleased with the results. Any time I am away for a bit I will take the couple seconds to squirt the carbs. I have exactly the same issue with my roach-chesters even after a rebuild.

                          Comment


                            #14
                            How many times do you pump the throttle when you first attempt to start it?

                            Comment


                              #15
                              I start with 3-4 pumps. Then I will pump another 3-4. Then i stop pumping and it finally turns over. I also have tried it without pumping the throttle and it takes about the same amount of time to start. Just picked up my new manifold gaset kit today so tomorrow I plan on pulling the carb and checking it out.

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