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Fuel filter

Discussion in 'Boats and Motors' started by HawgHunter, Sep 22, 2008.

  1. Ok, question for any motor mechanics out there. Had the boat out on Turkeyfoot Friday we used the main motor probably 5 times running betwenn spots and it ran fine, started easily and had no problems. We were trying to locate a hole that we had been told about and were running the motor at 2-3 MPH for about 10 minutes while checking for the depth we were looking for. The motor began to stall and a lifted the lever to rev the engine and instead of the RPMS increasing the motor cut out. I tried unsuccesfully to restart it but it would not start. We thought it may have flooded so we fished with the trolling motor for about 1/2 hour and then tried to start it again. I could start it if i choked it but as soon as I released the choke it died out again. The lever to rev the motor into higher RPMS did nothing. Knowing that after running it all day I should not have to choke it to get it to start I was thinking the fuel filter may be clogged and need replaced. Does this sound right and if not are there any other suggestions of what it might be. The motor is a 45HP Mercury outboard. If it sounds like the fuel filter any good websited on replacing it. Thanks for any help you can give.

    Scott
     
  2. check the squeeze blub /, fuel pump/ air vent on tank/ hose on the right direction , you can check the fuel pump ,pull the carb side off then crank see if it has a nice stream, .just some easy things to check . just a though some mostlikly a whole lot of fuel filters never get changed , if its just a inline filter a lawn garden repair shop should be able to match it up. or car parts store , I:D put my money on the fuel pump.
     

  3. UFM82

    UFM82 The one others want to be

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    You say that you can start the engine by choking it but it quits when you come off the choke. That tells you that the engine is getting fuel to the carb. Otherwise it wouldn't start at all. You also said that it ran fine until this suddenly happened. That tells me that the fuel line, primer bulb, vent, etc. are all doing what they are supposed to be doing. Now we need to figure out why the engine is starving for fuel when not being choked.
    The problem points to a clogged carb. Not the fuel filter as the carb is getting fuel as evidenced by the fact that it will run on the choke. Somewhere the fuel is being blocked in the normal run circuit. That points to the carb. The first thing I would do if possible is pull the bowl off the carb and look for debris in the bowl. If you find dirt in the bottom of the bowl, chances are the carb sucked dirt into a jet or passageway and it's preventing flow. Your course of action would be to pull the carb and as I always say, clean every passageway and jet in the carb. Use a can of carb cleaner and use the tube that come with it - spray the cleaner into any and every hole you find in the body of the carb. That will flush out any dirt that may be blocking a passageway. The space is very small in those passages and it doesn't take much to clog them. Once you have the carb cleaned, reassemble it and reinstall and see what it does. I believe it will fire up and run normally as you will have solved your problem. You didn't say what year the engine was but most outboards lead a tough life with intermittant use at best unless you are one of the lucky few who can devote lots of time to fishing/boating. It's very hard on an engine to be run for a few hours and then be left to sit for days or weeks or even months at a time.

    Don't just spray cleaner down the throat of the carb- that does nothing to clean the inside of the carb and it won't help your problem.

    UFM82
     
  4. ezbite

    ezbite the Susan Lucci of OGF

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    nice post, im having some similar problem with my kicker and you just gave me an idea too. thanks.
     
  5. OK, OK I chickened out. I went hom elast night intent on taking you guys advice. Pulled the shroud and cover off of the motor and there is a large cast iron (?) plate covering the front of the motor, blocking access to both carbs. I thought it was probably just a safety thing and was going to take it off to get to the carbs. The more I looked at it the more worried I got that I would not be able to take it off without screwing something else up. It is held on by no less than 6 bolts and there are numerous wires running into and through it. I imagine it is on some type of hinge since all the wires seem to run into the left side. I cant imagine taking all of these wires off to remove the plate and getting everything back together the way it is supposed to be. I believe it is a late 80's "Classic fifty" model Mercury 45HP if that helps. If anyone has a manual for these motors that I could borrow or can walk me through removing this plate I would appreciate it. If not I may just have to wait and take it to a marina to be looked at during the winter. I hate paying someone to so something I could probably do myself but like I said I am afraid of not getting it putback together right and causing myself even more trouble.

    Scott
     
  6. I forgot to mention both carbs were professionally rebuilt when we bought the boat at the end of last year, so I assume that the fuel filter would have beeen changed then but I will have to check the reciept at home to see if that is the case.

    Scott
     
  7. UFM82

    UFM82 The one others want to be

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    That would give you a "map" of where stuff goes when you reassemble. A manual is a must-have as well.

    UFM82
     
  8. I found the manuals on CD on ebay pretty reasonablly priced. When I go home this afternoon I will look up the exact year and model of the engine and order the CD. I will probably wait until it arrives before I try anything but I greatly appreciate your help and may have more questions once I get the manual

    Scott
     
  9. The 4 cylinder 45 hp motors were made from 1986 thru 1989 and were part of a family if 4 cylinder motors which were basically unchanged from 1976 thru 1992. Earlier versions were 50 hp which dropped to 45 hp in '86 probably due to power being rated at the prop rather than the crankshaft. In '90 they became 40 hp for some reason unknown to me. These motors have two carburetors each having a fuel pump integral to the carburetor. They have a fuel 'strainer' of sorts which may remove some 'chunks' but no other fuel filter unless one was added inline as an aftermarket item.

    I have owned two of these motors, an '88 model 45 hp which I bought new in '88 and ran for four years until I sold it with the boat. I currently have a '77 model 50 hp which ran great until the ignition system puked and the pushed the motor to the bottom of the project list. For what it is worth both of these motors were cold blooded. They ran great but if you shut them down for more than 15 minutes you had to choke them to restart.

    If the motor will run with the choke button pushed in I will have to agree with UFM (OH NO!) and say the carbs are blocked. Your motor probably does not have a traditional 'choke' system it has an 'enrichener' system which injects the fuel behind carburetors near the mounting flange. If this is the case it narrows down the problem.

    I'm not familiar with the manuals on CD but I do own a Seloc manual and it gives a pretty good desription of dismantling and cleaning and/or rebuilding of the carburetors. It does not describe removing/reinstalling the front plate so you are on your own there. My motor is not at the house but I believe you can just unbolt the plate and swing it out of the way and hang it by a string or wire. Just keep track of any wires you have to disconnect. If that scares you you might want to reconsider working on the carburetors. The carbs are pretty basic and can be easy to work on but they can also be easy to screw up.

    Just for shitz and giggles before taking anything apart get a socket or wrench on the carburetor mounting bolts and make sure they are snug. If the carbs were worked on last year they may have vibrated loose. Its a long shot but its worth a look.
     
  10. triton175

    triton175 STX 206 Viper

    Sounds like fouled plugs to me. Give them a quick check before you get too deep into the fuel system. It'll only take a minute, and might save you some headaches.

    Brian
     
  11. UFM82

    UFM82 The one others want to be

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    The engine runs on the choke. If the plugs were fouled, it wouldn't run at all.

    A "fouled" plug can describe any condition in which the gap across which the spark travels is shunted, thereby providing a path directly to ground or preventing the flow of current completely. When a plug fouls when you are cranking the engine it gets wet with liquid fuel. This prevents that spark from occurring and thus the engine doesn't start. Also, keep in mind that liquid fuel doesn't burn- just the vapor. If you get liquid fuel all over the plug, it won't fire and even if it does, the engine may not fire.
    You can also foul a plug with carbon deposits, physical damage from pre-ignition or other run-issues. I've even seen plugs fouled with aluminum from a piston that is melting down or breaking apart. But, no matter what is causing the fouling condition, the spark cannot spark and the engine will not start. The fact that he said the engine will start and run on the choke tells us that the plugs are not fouled.

    One more thing- fouled plugs are not necessarily junk plugs. If you have fuel -soaked plugs, simply dry them off. They've suffered no damage other than being wet and once dry, they will work just fine. If they have actuallt damage, replace them. Even carbon deposits can be cleaned off and the plugs re-used though. So a fouled plug isn't necessarily a throw-away. You don't throw towels away if you get them wet once do you?

    UFM82
     
  12. OK, the engine is a 1988 Mercury Classic 50 45HP according to the serial number. I picked up a Clymer's at the library and it describes very well rebuilding the carburetor but does not mention getting to the carburetor. I did find a blow up of the engine at Mercruiserparts.com and the part I am describing is call the front support bracket. That sounds pretty tame so I feel a little better about removing it. The wires running into the left side are two sets of wires running into some plug assemblies which are then screwed into the support assembly. I think I can just take the bolts off and swing the whole assembly out of the way without removing the wires to get to the carbs.

    I am really hoping that I pull it out of the garage, hook up the muffs and start the engine and it runs like it is supposed to. Maybe I will get lucky for a change and it was just vapor locked. Between working 60 hours a week and 3 kids in softball and soccer I havent got a chance to work on it yet. Any last minute advice before I jump into this.


    Scott
     
  13. UFM82

    UFM82 The one others want to be

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    Vapor lock used to occur when fuel, under negative pressure, (suction from the fuel pump) would boil in the fuel line. The mechanical fuel pumps actually pulled fuel from the tank before pumping it up to the carb. If the metal line was too close to a heat source the fuel could boil in the line and cause a vapor lock. Vapor can't be pumped by a 7 psi fuel pump and so the car would quit. However, that was then. Nowadays with in-tank fuel pumps that pressurize the fuel back at the tank and pump it forward, vapor lock is pretty much a thing of the past.

    Also, as I haven't seen metal fuel lines on outboards, the rubber lines insulate the fuel within and as most outboards don't get all that hot under the cowling, I don't see vapor lock as ever occurring. The conditions simply aren't there.

    It's good that you got a manual- however as you've seen the instructions for actually accessing parts sometimes lack a bit. A simple "remove the bracket" is oftentimes as detailed as it gets. Just keep close tabs on where stuff goes as you disassemble and it will help. Take notes if you want or sketch the layout. A picture of the engine before you start is invaluable and with digital cameras so accessible, a good photo shoot can help immensely.

    I still believe you have a carb issue. The engine may very well start and run fine for you. However, I think it would be due to whatever caused the clog has dislodged and is somewhere else. Once you start running again the same thing could happen again and then you're back to square one. The job can literally take just a couple hours max if you have a book and some mechanical aptitude. Dive in and see what happens. Good luck with it.

    UFM82
     
  14. I just came in and the boat ran fine in the driveway.I Let it run for 15-20 minutes with no problem. I mentioned vapor lock because I had read a discussion on one of the outboard troubleshooting forums and it sounded very similar to what was happening with my engine. I guess I could have been more accurate and said" I hope it is something minor that has worked itself out for now". I am still kicking around the idea of taking the carbs apart and cleaning them. Between the manual and the great advice from UFM I feel pretty confident that I could handle it. Thanks for all your help UFM and if I have more trouble with it or decide to tackle the carbs anyway I will definitely be seeking your guidance.

    Scott