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25 hp mercury outboard wont start

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xman33

Member
Hey guys thought you guys can shed some light on my problems. I have a 1980 mercury 25 hp. It starts with starting fluid only. To keep it from dying, i have to put it in gear and leave it running. The motor revs up fine and runs strong. But when engage in neutral it dies out and does'nt want to start unless i spray starting fluid directly inside the carb. But sometimes when the motor wants to start, it starts only when i have the throttle wide open in the foward position. Okay so this is where Im at. I took off the carb off and clean it with carb cleaner and reinstall with the old gasket. I know, I shouldve replace it with a new one but was told I can reuse the old one if they look fine. Okay so I got the motor running good for 5 minutes or so. Starts with first pull everytime in neutral position and seems to be running great. I then move on to the next step and tried adjusting my needle valve. Thats when then my problems starts all over again. It dies out when i put it in neutral and only starts with starting fluid. Any help will be great guys Im all ears. Im thinking it might be my float. But when I hold my carb right side up and tried blowing through it, it has resistant. Anybody knows whats the float level on this motor? Serial number is (9542340). My float is actually located on the inside of my bowl and not on the carb it self. Should I just leave it alone and not mess with it at all or what should I do? Is the old gasket the problem, do i need a new one? Is it my fuel pump? I can see gas dripping from the two holes inside my carb when pumping on gas. Any ideas would be great guys. Thanks
 
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IMG_1069.jpg heres a pics of my float.....;)
 
kimcrwbr1 said:
First off stop using starter fluid serious damage can occur it has no oil in it. Try tapping on the side of the carb with a wrench as you pump the primer bulb, if the primer bulb dont get hard the float needle needs replaced. Try running it out of fuel and with the primer bulb fill the carb with seafoam and let sit overnight it may be varnish on the float needle and seat. If you dont know how old the impeller is put a new one in. Turn the carb upside down and with the weight of the float only you want the float to be 1/4 inch above the gasket surface of the carb body to adjust it pull the float out and bend the tang and check it again never press on the float with your finger.
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Thanks for the help response kmcrwr1. Ok so Before it didnt get hard, the primer bulb. Now that Ive rebuild the carb and clean the float bowl it does get hard when I pump it and stays hard.So I think that checks out good. So now with the float question. My float and needle is seated inside the float bowl. How can I measure it with out taking it out. Its not like any other carbs were its seated on the carb itself which you can turn upside down and wont fall off. I posted a pics above where the float is located to give you guys a idea.
thanks
 
xman33 said:
Thanks for the help response kmcrwr1. Ok so Before it didnt get hard, the primer bulb. Now that Ive rebuild the carb and clean the float bowl it does get hard when I pump it and stays hard.So I think that checks out good. So now with the float question. My float and needle is seated inside the float bowl. How can I measure it with out taking it out. Its not like any other carbs were its seated on the carb itself which you can turn upside down and wont fall off. I posted a pics above where the float is located to give you guys a idea.
thanks
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heres a pics of my float inside the float bowl. As You can see its seated inside of it not on the carb itself. The other pics is the gasket. It goes between the carb and the float. Should i change it or leave it?
 

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kimcrwbr1 said:
The float needle is in the float bowl allways use the new gasket if you have one. To adjust the float turn the float bowl upside down with only trhe weight of the float on the float needle from the surface where the gasket sits measure 1/32 of a inch above the bowl it states as close to 1/32 as possible, do not press on the float with your finger to adjust it pull the float out and ever so slightly bend the tab that pushes the float needle and then put it in and check it. Normally they are pretty close but still good to confirm it. Then you should be able to adjust the low speed needle. With the engine up to temp in gear in the water slowly making 1/8 turns at a time and wait 15 seconds between adjustments first turn it out until it coughs note that position then turn it in until it stumbles and split the difference. Let the engine fully cool down usually overnight and then see how easy it cold starts you may need to turn it a little rich for cold starts and it helps protect the engine at idle speeds from lack of oil especially if you do alot of trolling. Did you put a new carb gasket on it and check the mount surface was good and flat?
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thanks for the info (kimcrwbr1). I did not know that this carb had a low speed needle idle. I took off the high speed inlet needle only on my first attempt and clean it but there was also one more bolt next to it. I was wondering what it was. It was in very tight. It took me awhile to get it out but I eventually got it free. When I tired reinstalling it the (L) needle nut, I screw it in as tight as i could like how it was in before. The one on the picture with the (L) on it. Maybe that's what I did wrong. I was trying to adjust my high inlet needle while I had my low speed needle so closely tighten. I post up a pics (L) for low and (h) for high inlet needle. Let me know if thats correct. My drawing sucks so forgive me =). I decided and went ahead to order a new carb kit today and started fresh while everything is out. The only thing that i couldnt get was the needle because their not available anymore . I guess I just try and clean it as good as I can. The needle tip is plastic rubber so I gotten it as clean as i could. I will tried to measure my float bowl tonight and see where im at. Let me know if im measuring it correctly. Im measuring it from top float to top bowl correct ?Heres a pics of it also let me know if im doing it wrong. In the meantime ill just have to recleaned my carb while waiting for my carb kit =)...
thanks
 

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kimcrwbr1 said:
http://www.marineengine.com/parts/m.../5705532-thru-6416712-usa/carburetor-assembly Item #3 look close that it has a nice smooth taper on the tip if it has a groov cut from being too tight you may be able to dress it up with a drill and a chunk of sandpaper fine grit and get the taper smooth and knock the tip down so it fully seats. Turn it in to lightly seated and then back it out 1 1/2 turns initial adjustment and adjust it in the water after the engine is warm in forward gear. To check your throttle pickup with a timing light on the #1 plug wire advance the throttle so the two dots on the flywheel are in line with the timing mark on the starter housing, the strait line on the throttle cam should be within 1/16 inch from the roller to adjust it with the throttle lever on the starbor side of the engine. once you get that adjusted set the idle speed by adjusting the idle screw for best performance and use the idle stop screw to obtain between 700-800 rpm. at this speed the stem of the daspot should be fully depressed if not make the necessary adjustment. Shift into neutral and move the primer/fast/idle knob into the center detent and adjust the ratchet for a good fast idle rpm between 1400-1700. To check max spark advance with the timing light connected at WOT you want the three dots on the flywheel to line up with the mark on the starter housing you adjust it with the link rod shorten it to retard and lengthen it to advance the timing. If you didnt mess with these adjustments they should be ok but couldnt hurt to check. You will probably need some smooth water to check the max advance at WOT.
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okay...If number #3 is the low idle needle then I didnt mess anything up. I didnt screw it tight and the needle looks good.The screw #32 was the one i was talking about. I dont know if it was suppose to be on very tight but i tighten it just like how it was on before. Thanks for going deep into details about checking and adjusting the motor. I will do that as soon as i get the motor up and running and let you know how it goes. While im waiting for my carb kit. I wanna to check and see if the imppeller is still good. Theres four bolts on the bottom shaft, do i take those off and the lower units just comes out or is there more to it?

thanks
 
kimcrwbr1 said:
It looks to me like all you do is pull the four bolts and drop the gearbox someone here will know for sure. when your putting the new impeller in you may as well while you have it apart turn the driveshaft clockwise and never turn it backwards after the new impeller is in. Put some dish soap on the new impeller to lube it up for the initial spin up. If it was pumping water before you take it apart likely the impeller is all you need but a pump kit would be nice to have on hand just in case.
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Well im pretty sure my impeller may still be working good.It has a steady peeing like flow coming out the back. But doesn't hurt to check n see if it's still good.
thanks :) A million
 
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kimcrwbr1 said:
The float needle is in the float bowl allways use the new gasket if you have one. To adjust the float turn the float bowl upside down with only trhe weight of the float on the float needle from the surface where the gasket sits measure 1/32 of a inch above the bowl it states as close to 1/32 as possible, do not press on the float with your finger to adjust it pull the float out and ever so slightly bend the tab that pushes the float needle and then put it in and check it. Normally they are pretty close but still good to confirm it. Then you should be able to adjust the low speed needle. With the engine up to temp in gear in the water slowly making 1/8 turns at a time and wait 15 seconds between adjustments first turn it out until it coughs note that position then turn it in until it stumbles and split the difference. Let the engine fully cool down usually overnight and then see how easy it cold starts you may need to turn it a little rich for cold starts and it helps protect the engine at idle speeds from lack of oil especially if you do alot of trolling. Did you put a new carb gasket on it and check the mount surface was good and flat?
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Okay, so I got carb kit and Rebuild my carb tody for the second time. I even boil it for 20 min and recleaned it.Reset my float heights and spark plug to mercury spec. New fuel pump also. The motor is still doing what it did before. Won't start up. It fire up with starting fluid just fine and would run if I give it gas on throttle .My sparks are orange n bright blue. I'm scratching my head here. Is there anything I'm missing or am I doing something wrong? I also put new gas In my tank and siphon all the old gas away. Any idea would be greatful. I'm at wits end.
 
hey fellas, this is my first time using these forums so bare with me. i have 1989 johnson outboard 30 hp. i just bought the boat and im trying to get it to run right. i can get it to crank but only when i hold my hand over the carb it cranks. i already bought a new carb kit and installed it and also a new fuel pump. new fuel lines... the whole shooting match. i also changed the coils, wires and plugs. the motor runs great just my problem is i cant get it to start without my hand over the carb. can someone please help!?!?!
 
kimcrwbr1 said:
Pull the coils and sand the base to good alumninum and clean the ground wire on the base of the coil and see if you get even spark on both plugs. use a spark gap tester you want the spark to jump a gap of at least 3/8 inch brite blue snap.
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Update, I finally got around and bought a new spark plug gap tester. *I clean and sanded all the grounds and now I finaly got blue sparks. The sparks on both plugs are jumping fine at 3/8. Ok now on to testing my coils. I am getting some *funnie readings or maybe my coils are bad. Here are the *numbers. On both coils for the primary I got readings of 0.6 ohms. On the secondarys, I got a reading of .916 ohms stable while the other coil was jumping up and down from *.206 to 959 back to o. Sometimes it would give me a reading n sometimes not. I'm thinking maybe one of my coils is fried, but if it's fried why would I still get spark and a 3/8 jump. Bad news I also broke the main jet screw on the float bowl becuase it was plastic made. Can I replace it with any screw or do i have to buy a original one . I'm outa luck because it's no longer available( aboselte).
Any ideas would be great guys. I appreciate all your help so far. I just want to get this motor running again before winter starts.:(
 
kimcrwbr1 said:
Bummer deal on the high speed jet. I did some research and maybe you can get a used carb with a good part even seaway says it is unavailable. Maybe give them a call and see what they suggest. http://www.seawaymarine.com/ m-f weekdays
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Good news and bad news. I stuck a old screw and it seems to hold on the main jet. Planning to silicon and leave it alone for now. Bad news, now one of my coils aren't sparking. I check out the non sparking coils and it's in spec still. The green/white wire coming for the switch box is dead. I switch the good wire from the switch box to the no sparking coils and got sparks. Is my switch box fried or my stator? My wife's want me to toss this motor in the trash and buy a new but I love the way it goes in the water. It gets up fast and strong. TThe funnie thing is that I can still run my engine with one spark *in one of my cylinders. I'm very close to tossing this out tommorow on trash day. Any suggestions? Thanks for helping me out so far youve been great. If the stator
checks out bad, i think the garbage man will get a good use motor, rruns but doesn't start:). I'm getting tired of fiddling with this motor.
 
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Change plug wires and see if it moves w/the wire. Clean the ground connections under the coils to bare metal.
 
guyjg said:
Change plug wires and see if it moves w/the wire. Clean the ground connections under the coils to bare metal.
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I did what you said and it stayed the same...im guessing its the coil but not too sure because while i was at it, i also installed new spark plugs and it still wont turn over. It sounds like its lacking something. I took out the new spark and i didnt see any gasoline on it. Am i suppose to see gas and oil on my spark plugs. Its clean and fresh still after 20 rope pulls. Theres gas in my carb because i can see it comming out of the two small jets if i prime it many times. I rebuild my carb and relpace my fuel pump diaphragm aready. I must be missing something. But what ?
 
guyjg said:
Swap coil positions and see if the issue follows the coil.
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Okay so I swapt the coils and the problems still persist. Though now i can get a better reading on the secondary coil of the coil that i thought was bad, its at .950 ohm which before i couldnt make a reading off it so i think the coil is good still good '" MAYBE". I also tried spraying fuel mix in the plug holes and* let it sit before trying to start it. It did start up with the throttle open fully wide but doesn't start on neutral ( the start position). I havent got the chance to get fogging oil and spray down the plugs holes. Ill tried that out next. Should i spray the whole bottle in there or couple sprays?

Thanks guys for helping me out so far. I can feel that Im almost pin pointing out the problem on my motor. I can hear it pop when trying to crank it over. Ive got sparks on both coils that jumps at 3/8 inch gap. I have two spark plug tester also. One test the spark gap* jump and the other test for sparks. I get orange, voilet and light blue on the coils with the spark tester and on my* spark gap tester i get the color light blue streak jumping gap. Is my coil still too weak to make a good spark to ignite? It starts if i spray starting fluid still but I dont think i wanna go that route anymore. =)
 
kimcrwbr1 said:
If you have it running no need to fog it that was just to get lube into the powerhead and cylinders as long as you using a good oil in your fuel you should be good there. Have you adjusted the low speed needle after you bring it up to temp. With the engine up to temp in gear in the water adjust the low needle out counterclockwise until the engine loads up or coughs 1/8 turn at a time and wait 20 seconds for the engine to stabilize. Get it to cough and slowly turn it in for a nice smooth idle. It may just be too lean on the idle air you want it on the rich side for cold starts and to protect the motor at low speeds. Allways make that adjustment when the engine is under a load.
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Yea I aready tried that. I got the engine running smooth but as soon as I kill the engine, it does not wanna start. Im looking at the manual and its says i should get a reading of 0 ohms on my primary but I am getting a reading of .06 on both coils. I am getting spark and a 3/8 gap jump also.Do you think my coils are bad since im getting a reading of 0.06 on it? Let me know if im reading it correctly thanks.
 
kimcrwbr1 said:
Have you done a de-carb? Get a can of seafoam spray and get the engine hot rev it up to around 2000 rpm and spray seafoam into the carb short spurts until it starts to smoke real good and quickly shut it down. Let it sit for 1/2 hour or so then start it and run it around 3000 rpm until the smoke clears out. That will clean the carbon off the rings, pistons and cylinders and you will probably get alot of black crap out the exhaust. If your running in a barrel drain it and refill with fresh water. To check if it helped check the compression cold first, do the de-carb and check the compression again after the engine fully cools down.
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I haven't de-carb my engine yet, though that will be my next move. My boat is in my garage, running it is bad enough for me as it is. I can barely breath in there while the engine is running. I know how sea foam works and for sure my neighbors might think i have a garage fire and might call the fire dept =). It be nice if it was in the open. Ill try figuring out something and go from there. Seam foaming the carbs sounds like a good idea. thanks Ill let u know how it goes.
 
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