1988 Mariner 50 HP 2-stroke oil injected

[judyglen]

The 3 cylinder engine starts great, will rev up when idling but when placed in gear the boat will only travel at about half speed. I have installed three new spark plugs, new gas lines as well as new gas filters on the oil injection system and on the in-line at the side of the engine. Gas is new. Oil is new. It still does the same thing - no speed. <br /><br />History: I went across the lake and the boat was working famously. I trolled for about 45 minutes and then when I started to head home the engine started working as described above. It is still doing it after the items, listed above, were changed. Looking for suggestions as to what to do next? <br /><br />Glenn

 

[andy6374]

Re: 1988 Mariner 50 HP 2-stroke oil injected

How fast do you go and at what RPMs? Does it just not move at all? Or, do you throw into to gear and give it some throttle and then the engine boggs down on you, as if it isn't getting any gas?<br /><br />-Andy

 

[judyglen]

Re: 1988 Mariner 50 HP 2-stroke oil injected

Originally posted by andy6374:<br /> How fast do you go and at what RPMs? Does it just not move at all? Or, do you throw into to gear and give it some throttle and then the engine boggs down on you, as if it isn't getting any gas?<br /><br />-Andy

Hi Andy, thanks for your quick response. I don't have a tachometer on my boat therefore I am unable to tell you the RsPM. The boat moves at about half the speed it used to go at. When I push the throttle all the way forward the engine only revs up about half the amount it used to and the boat therefore only goes about half speed. All the gas hoses and filters have been changed. Could it be a coil or one cylinder not firing. If so, how do I check that without frying myself. You have no doubt determined that I know very little about mechanics but I can do some things with it. Thanks again. Glenn

 

[andy6374]

Re: 1988 Mariner 50 HP 2-stroke oil injected

Trust me, I knew nothing about working on my merc. The more you try the more you will learn and the better you will get. The fact you are trying to figure it out and fix yourself is great! <br /><br />Since you are a doityourselfer.. Get a manual, mulitmeter(Doesn't have to be fancy) and spark tester (something you hook up between the spark plug in the ignition boot and it flashes a light when it gets a spark).<br /><br />No back to your problem.<br /><br />If you don't have spark on all cylinders, sure that would cause a great lose in horsepower. To check for spark you can take the ignition "boot" off the spark plug, place it near a ground (engine powerhead) crank the engine and check if you see spark. A spark tester would be easier. Do one at a time. If you don't have spark, get back to me. If you do have spark then...<br /><br />It most certainly is your carbs or fuel pump. To test the fuel pump, pump the primer bulb while in gear and see if your speed increases. If it does, then your fuel pump is bad. If not, your carbs are gummed up and need a cleaning. Which I can walk you through.<br /><br />Get back to me-<br />andy

 

[judyglen]

Re: 1988 Mariner 50 HP 2-stroke oil injected

I have tried squeezing the gas primer bulb when underway and there is no variance in speed. (The engine worked very well and the carbs were working great before the 45-60 minutes of trolling)<br /><br />I will purchase a spark tester and try that next. My boat is at the cottage, about 40 miles away so it will be a little time before I get back to you on the spark question. I think I will bring it back home with me so I can try various things in my yard as I hear back from you and others. I thank you for your time,interest and assistance.<br /><br />Glenn

 

[andy6374]

Re: 1988 Mariner 50 HP 2-stroke oil injected

As a note. I went out to fish, worked well at WOT. Trolled all day. On the way back all I had was half power. It turned out to be dirty carbs, yep just like that. Like day and night.<br /><br />andy

 

[judyglen]

Re: 1988 Mariner 50 HP 2-stroke oil injected

Originally posted by andy6374:<br /> As a note. I went out to fish, worked well at WOT. Trolled all day. On the way back all I had was half power. It turned out to be dirty carbs, yep just like that. Like day and night.<br /><br />andy

Hi Andy. Your experience sounds exactly the same as what happened to me. Anyway, I acquired a spark tester today and plan to go out to the lake in the morning and test the spark. If there is no spark on one or more wires then we may have found the problem but if not then there is the other - remove the carburetors and clean them. One person mentioned to me today that there is a spray that you can use to clean the carburetors. Are you aware of what they are talking about and does it actually work? How difficult is it to remove the carburetors? I looked in there yesterday to see if they were fully opening when I put the speed control all the way forward and they did open all the way. There is little space in there to work. Hoping to hear from you on this request. Thanks. Glenn

 

[andy6374]

Re: 1988 Mariner 50 HP 2-stroke oil injected

I am aware of the spray stuff you speak of and...it doesn't even scratch the surface. The most tiny bit of gum can give you a can of worms. A full disassembly is necessary, that is if you have spark on all cylinders. <br /><br />Removing the carbs is easy, I could give a walk through if you like and then a walk through the clean and reassembling. A digital camera is useful when disassembling so you can see how it looked befor you took it off. Even better, a picture will show me what type of carbs you have. Check to see if you have the carbs that fit this description.<br /><br />-With the front cowling cover and air intake box off.<br />-You see the throttle sutters inside the carb throats(which you said open all the way when you go to full throttle).<br />- There should be to plugs on either side, same level as the carb throats, those are the idle jet plugs.<br />-There should be a bowl under that, attached to the upper part of the carb with 6 retaining screws. On either side of the bowl should by two plugs (the main jet plugs)<br />-And finally to complete the description, on the top of the carbs should be a metal plate.<br /><br />If you have these carbs, they are the same ones I have I can help you clean them. If not you will need to get a Seloc or merc factory manual on your engine (Which you should get anyways, they pay for themselves).

 

[judyglen]

Re: 1988 Mariner 50 HP 2-stroke oil injected

Originally posted by andy6374:<br /> I am aware of the spray stuff you speak of and...it doesn't even scratch the surface. The most tiny bit of gum can give you a can of worms. A full disassembly is necessary, that is if you have spark on all cylinders. <br /><br />Removing the carbs is easy, I could give a walk through if you like and then a walk through the clean and reassembling. A digital camera is useful when disassembling so you can see how it looked befor you took it off. Even better, a picture will show me what type of carbs you have. Check to see if you have the carbs that fit this description.<br /><br />-With the front cowling cover and air intake box off.<br />-You see the throttle sutters inside the carb throats(which you said open all the way when you go to full throttle).<br />- There should be to plugs on either side, same level as the carb throats, those are the idle jet plugs.<br />-There should be a bowl under that, attached to the upper part of the carb with 6 retaining screws. On either side of the bowl should by two plugs (the main jet plugs)<br />-And finally to complete the description, on the top of the carbs should be a metal plate.<br /><br />If you have these carbs, they are the same ones I have I can help you clean them. If not you will need to get a Seloc or merc factory manual on your engine (Which you should get anyways, they pay for themselves).

 

[judyglen]

Re: 1988 Mariner 50 HP 2-stroke oil injected

Hi Andy. Well I went out to the lake and checked the spark with the spark checker. All three wires produced a very blue spark for over 3/4 inch so I guess that is not a problem. I also checked the spark plugs and they are firing great as well.<br />I then took off the carburetors and have brought them home with me (quite easy as you said). Where the carbs attach to the motor - the gaskets remained attached to the motor and on inspection looked just fine, so I left them there. I have the two carbs here and am about to clean them, with your help. They appear to be exactly the same as you described in your last correspondence. When I reassemble the carburetors I intend to place all new gas lines that go to the fuel pump, from the fuel pump to the carburetors and new line connecting the two carbs. I may have problems getting a gasket kit here in the backwoods of New Brunswick so I hope I can reuse the ones that are there. Oh yes, I fully intend to obtain a manual for the engine.<br /><br />Await your response. Glenn

 

[andy6374]

Re: 1988 Mariner 50 HP 2-stroke oil injected

You will need to order a set a gaskets via the internet, if you can't readily get them. You have to have new gaskets. They are cheap.<br /><br /> http://www.iboats.com/mall/partfind...&gd_poid=112060&gd_row=48&**********=87776537 <br /><br />This is supposed to be the gasket set for your carbs. You will need three sets. Takes your carbs apart to make sure these gaskets look like yours. Remember to take apart carefully (and take pictures if need be) to remember how to reassemble.<br /><br />Was there a set of gaskets between the carb throat and the air intake? Not the gaskets you said you left on the motor (intake manifold).<br /><br />-andy

 

[judyglen]

Re: 1988 Mariner 50 HP 2-stroke oil injected

Originally posted by andy6374:<br /> You will need to order a set a gaskets via the internet, if you can't readily get them. You have to have new gaskets. They are cheap.<br /><br /> http://www.iboats.com/mall/partfind...&gd_poid=112060&gd_row=48&**********=87776537 <br /><br />This is supposed to be the gasket set for your carbs. You will need three sets. Takes your carbs apart to make sure these gaskets look like yours. Remember to take apart carefully (and take pictures if need be) to remember how to reassemble.<br /><br />Was there a set of gaskets between the carb throat and the air intake? Not the gaskets you said you left on the motor (intake manifold).<br /><br />-andy

Carbs have been taken apart and cleaned. Able to reuse the gaskets as they came apart very easily without breaking at all. The carbs were quite clean and did not look as though they would be my problem. Thank you for getting back to me. I did not remember seeing any gaskets betweeen the carb throat and the air intake. <br /><br />I am heading back out to the lake now to test the compression and put the carbs back on. At the same time I am going to put all new gas lines to and from the fuel pump.<br /><br />I will contact you to let you know how I make out. <br /><br />Do you know what the compression should be on each cylinder?<br /><br />Glenn

 

[judyglen]

Re: 1988 Mariner 50 HP 2-stroke oil injected

Yes, the gaskets you have shown appear to be the same as mine takes.<br /><br />Glenn

 

[andy6374]

Re: 1988 Mariner 50 HP 2-stroke oil injected

Trust me, please. My carbs looked so clean when I disassembled them I figured I could eat off them. But they weren't. You can't see inside every little tiny orfice. That's where the clogs are. That's why you have to soak them in the carb cleaner you can purchase by the gallon. You will see black sut spitting from your carbs.<br /><br />Also you will need new gaskets. You might live and learn, but... Even if they look good, they will not make a proper seal.<br /><br />There is no proper compression persay, rather each cylinder should be within 10% of each other. Like 105, 110, 105 would be good. 120 110 115 would be good. 130 125 100 would be bad<br /><br />-Andy

 

[judyglen]

Re: 1988 Mariner 50 HP 2-stroke oil injected

Originally posted by andy6374:<br /> Trust me, please. My carbs looked so clean when I disassembled them I figured I could eat off them. But they weren't. You can't see inside every little tiny orfice. That's where the clogs are. That's why you have to soak them in the carb cleaner you can purchase by the gallon. You will see black sut spitting from your carbs.<br /><br />Also you will need new gaskets. You might live and learn, but... Even if they look good, they will not make a proper seal.<br /><br />There is no proper compression persay, rather each cylinder should be within 10% of each other. Like 105, 110, 105 would be good. 120 110 115 would be good. 130 125 100 would be bad<br /><br />-Andy

 

[judyglen]

Re: 1988 Mariner 50 HP 2-stroke oil injected

Andy. I have located the problem. There is a little mickey mouse plastic item between the two carburetors that controls the valve on the lower carburetor. Somehow that has been crushed and the second carburetor could not operate. Makes sense once I looked at it. Anyway, I used a tie tag to keep the plastic item up where the spring could penetrate it and then both veunturas(?) now open at the same time rather than just one opening allowing me to only go at half speed. I put the boat in the water and it works excellent. I have to get one of those plastic parts as my modification will not last forever. At least I know what the problem was and can fix it should it do it again before I get the part. By the way I took the compression while I was there and it read 110-110-110 so I guess there is no problem there. It works great now but I must get a manual so I can look up the parts I need to make it right. I thank you so much for your keen interest and most helpful information. Keep up the good work. Thanks. Glenn

 

[andy6374]

Re: 1988 Mariner 50 HP 2-stroke oil injected

Good work my friend. Something stupid, it's always the case. Well you've nailed and now you have a running engine. Glad to hear it!<br /><br />-andy

 

[judyglen]

Re: 1988 Mariner 50 HP 2-stroke oil injected

Originally posted by andy6374:<br /> Good work my friend. Something stupid, it's always the case. Well you've nailed and now you have a running engine. Glad to hear it!<br /><br />-andy

Well now Andy. When do you plan to come to New Brunswick to see how this old boat works and possibly catch some FISH. Open invitation to you. Thanks again Andy. Glenn