• 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 elseís 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 itís posted at the end of someone elseís 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

mercruiser 5.0 dies

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


  • mercruiser 5.0 dies

    I have 1994 5.0 liter with a mercruiser alpha one outdrive,with a quadrajet carb. The engine has a low hours but has been sittting a while. The problem with the motor is it will idle good for about a minute at 800 rpm then the engine speeds up to about 2500 and then dies.If you give the engine some gas it will keep running but it is really rough. After about 30 more secounds it will die. The engine also feels very hot to the touch after only a few minutes of running and it appears to be running rich via the large amount of black smoke coming from the exhaust. The problem to me sounded like the carb, so i bought a rebuild kit and installed it. I dont know much about carbs so i had my father talk me through it. I made sure the float was set to the charts spec. then reinstalled it. The same problem was still there. The engine also has a knocking/rattle coming from between the engine and the outdrive which speeds up with the engine rpm. I have rented a compression tester and all the cylinders were good. Any help whould be greatly appreciated.


  • #2
    Re: mercruiser 5.0 dies

    The engine also feels very hot to the touch after only a few minutes of running and it appears to be running rich via the large amount of black smoke coming from the exhaust
    Sounds like you may have the choke too tight, or it is not opening. Also....If you are use to fuel injected cars and this is your first engine with a carb, you have to give it some throttle to clear it out or it will just flood itself out.Instead of letting it idle at 700 rpm, bring the throttle up to 1200 to 1500 rpm and let it warm up.Did you have water hooked to the outdrive when you were running it? If not, you have probably destroyed the raw water impeller, or it was bad to begin with. If you have an Alpha drive the impeller is in the drive, with a Bravo drive the impeller is in the engine mounted pump.Do you have a service manual?????The engine may also need a good old tuneup. Plugs, cap, rotor, set timing etc.
    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



    • #3
      Re: mercruiser 5.0 dies

      And don't run it with the drive in the full up (trailering) position.

      Comment



      • #4
        Re: mercruiser 5.0 dies

        The carb has a manual choke and it is open all the way.I alao had the water hooked up and it seemed to be spiting alot of water out of the exhuast so i guess its pumping the prop amount of water.I've tired raising the idle to around 1200 and still after a few minutes it just shuts down. When its dying I can either hit the choke or pump it a few times so it gets gas and it tries to stay running but I dont think its getting enough gas to stay running. I was thinking it might be the fuel pump or maybe a dirty filter, but I'm not sure. I also just gave it a tune up and I installed a new filter in the side of the carb. I dont have a service manual for the engine. I was thinking about buying a tempature gun to see if it is just me thinking it is get to hot.

        Comment



        • #5
          Re: mercruiser 5.0 dies

          Have you checked the fuel pump pressure? How about the water seperating fuel filter?
          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



          • #6
            Re: mercruiser 5.0 dies

            I was thinking it might be the fuel pump or maybe a dirty filter, but I'm not sure.
            I Think This Is your Problem...........Lack of Fuel.........You Need 4psi to 6psi of Clean Fuel, At the Carb inlet to run......It Could be Anything between the Tank,+ Carb..... including the Tank,+ Carb.....
            Any Grease is Better,..... Than No Grease at All.......

            Comment



            • #7
              Re: mercruiser 5.0 dies

              sounds like to much fuel, NOT an indicator of a plugged fuel filter, which would lean it out if anything (its never the fuel filter)if new to carbs,especially if new to them AND taken it apart, I would suggest a NEW NOT REMAN one. Carbs-=mechanical EFI=electronical, VERY DIFFERENT ANIMALS New to carbs and trying a rebuild. I would suggest getting a whole new carb no doubtyou can find them NEW 200-300 bucks online maybe chaeper if you look hard enough well maybe I should never say never, but if running overly rich it aint gonna be the filter

              Comment



              • #8
                Re: mercruiser 5.0 dies

                most likely a heavy float IF the choke working okay

                Comment



                • #9
                  Re: mercruiser 5.0 dies

                  if an engine cuts out due to too little fuel (too much air not enough gas) it will do so quite abruptly when the throttle is opened with quite likely a blow back thru the carb..if it cuts out due to too much fuel (too much gas not enough air) it will do so slowly when the throttle is opened with lots of black smoke and a slow spluttery die off..the difference between the two is quite obvious.. in fact without a carb fitted at all.. simply pouring say an egg-cup full of gas into the manifold hole then cranking the engine over should produce four or five seconds of full engine rev range followed by an instant cut out when the gas u poured in runs out. basially all the clever bits in a carb aint really needed for simplistic flat out running they are more to do with economy.. clean pick up thru the engines part throttle range and steady reliable idle than anything else..idling at 800 rpm then going up to 2500 rpm and dying without touching the throttle makes no sense at all.. i think u need to make sure u have decent gas in it before going much further.. as for the engine getting hot that sounds like a completely different problem..trog100

                  Comment



                  • #10
                    Re: mercruiser 5.0 dies

                    My '95 5.7 was acting like this. It turned out that the ignition module was going bad. There are some troubleshooting procedures in the shop manual to go through that can identify the different problems. Just replacing parts in the hopes that you will fix the problem without knowing what is wrong can be both expensive and frustrating.

                    Comment



                    • #11
                      Re: mercruiser 5.0 dies

                      Thank you for the replies, it turned out that the over heating problem was the water pump and the engine shutting off was the carb. I just took it to the nearst auto shop and they let it soak it carb cleaner over night, then we put it back together and its running fine. I also replaced the gas, which didnt smell old, but better to be safe then sorry.

                      Comment



                      • #12
                        Re: mercruiser 5.0 dies

                        The problem to me sounded like the carb, so i bought a rebuild kit and installed it.
                        I'm Glad you found the problem.............There's More to a carb kit, Than Changing a few Gaskets.............. Boats.....................Quite a Learning Experince, Aren't They ????
                        Any Grease is Better,..... Than No Grease at All.......

                        Comment

                        Working...
                        X