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Johnson Motor will not start or stay running

J

Johnboy1

New member
I have a 1992 Johnson 48SPL Model #J48ESLENB. The motor was given to me by my Grandfather and it had been sitting for awhile. The motor would not start at first without spraying a small amount of starting fluid into the Carburetors and then it would start up but would run rough. So I drained the gas tank as the gas smelled bad so I drained and cleaned the tank and new ethanol free gas and oil 50:1in it. The motor still would not start up without using a little bit of starting fluid. It ran rough for a little bit and then smoothed out. Ran for about 15 minutes on the hose and then turned it off. About an hour later tried to start but would not without using starting fluid. Could still smell odor of bad gas. It ran smooth for a few minutes then began running rough and shut off and would not start back up. Both spark plugs have hot blue fire. Checked fuel pump and diaphragm has hoe n it and a lot of small trash and debris in pump. So I rebuilt the pump. Motor will start up briefly run rough and then shutoff. Should I check the carburetors and clean or rebuild them. I have not checked the compression in the cylinders as I do not know what it should be. Thanking anyone in advance for any information or assistance
 
First check the compression. Then the spark which should jump a 7/16" open air gap on a tester. If that's okay do the carb.
 
Thank you Boobie. I have checked the spark and it is oK. I will check the compression as soon as I find out how much the compression should be. I have a compression tester. How difficult is it to clean and or rebuild the Carbs, on my 1992 Johnson 48SPL.
 
Carburetors generally will need cleaning.-----------Not much to them and rarely do they wear out.--------Just do one at a time and use the other for reference if you need to.-----------After you are done you will say---" that was easy "
 
Thank you racerone I will give it a try as soon as I get my service manual that will show me a diagram of the carburetors and how to do it.
 
Is the starting fluid bad for the motor. I did not use but a small spray not much to get the motor to start as all it would originally do was spin over and not fire even though there was good fire at the spark plugs
 
Some folks jump up and down and say starting fluid is bad, not sure why that is.------An outboard that is cold will have lots of clearance on the parts.----An outboard that has not run for a while will have lots of oil all over the bearings and cylinders.-------Using quick start in wee amounts is not a problem !!!!
 
racerone said:
Some folks jump up and down and say starting fluid is bad, not sure why that is.------An outboard that is cold will have lots of clearance on the parts.----An outboard that has not run for a while will have lots of oil all over the bearings and cylinders.-------Using quick start in wee amounts is not a problem !!!!
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Thank you racerone for your response. I was beginning to get a little bit worried about what the other guy said. I am new to this but it is not like I sprayed a whole bunch of starting fluid into the motor, just a little bit as it was cold and had been sitting for several days. I knew that fire was getting to the plugs and thought that enough fuel was getting to and going through the carburetors but could no understand why e motor would not start up so I spy a little bit of the starting fluid. Now I know that my problem was trash in and hole in fuel pump, and also probably trash in carburetors. So now I will be cleaning carbs and putting a filter in fuel line between tank and motor. Where is best place for filter, near tank or near motor?
 
racerone said:
Carburetors generally will need cleaning.-----------Not much to them and rarely do they wear out.--------Just do one at a time and use the other for reference if you need to.-----------After you are done you will say---" that was easy "
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Racerone when you say clean the Carbs, does this mean that I need to remove them from the motor, disassemble them, clean them and then put them back together. Do I need to get rebuild kits for the Carbs to do this, or do I just clean everything up with carburetor cleaner and put them back together. Someone told me that I might be able to clean them by removing the float bowl screw and spray some carb cleaner in there and let it set for awhile and then drain it out.
 
Boobie said:
The proper way is to take them all apart, clean them and install new kits. Then check your sync and link.
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I rebuilt both Carbs, wasn't too bad. I also checked the compression and the top cylinder has 150 and the bottom cylinder has 145. The motor starts up now but runs a little rough as though it is only running on 1 and a half cylinders. Do I need to make an adjustment with a fuel mixture screw or something to get it to smooth out, and I so which screw and how much. I did not turn or mess with any of the adjustment screws during my disassembly or assembly of the Carbs
 
kimcrwbr1 said:
If you didnt pull the jets and soft plugs then you just cleaned the carbs you did not rebuild them.
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I bought two Carb rebuild kits and put everything that was in the kits into the Carbs without pulling the jets and soft plugs because I did not want to change or mess up their settings, as I did not know how to readjust them. Is it possible to remove them now and clean them without having to remove the Carbs and disassemble them again. I am new t this and thought that ifI id not remove them that they would be okay.
 
kimcrwbr1 said:
Are they the early production or the late? The late production has the flat cover on the top of the carbs. Count the turns in of the slow needles until lightly seated and then back them out 1 1/2 turns. On the bottom of the float bowls is a drain screw and the high speed jets are inside. Pull the jets and clean them with a soft copper wire so you dont ream them out. Make sure the screwdriver fits good so grind down a wider screwdriver to just fit inside the threads as they are in there pretty tight. On the front of the carbs is the intermediate jets do the same with them you may need to make a special screwdriver to fit them also. You may be able to just stick a copper wire in them and clean them without pulling them? Make sure both carbs open exactly the same time and then check engine sync. There is a mark on the throttle cam the carbs should just begin to open as the mark passes center of the follower roller that opens the butterflys. Start the motor and bring it up to temp first and then in a barrel of water in gear adjust the slow needles. Turn the needle in clockwise until the engine cuts out and back out for a smooth idle. Do that to both carbs a couple times and adjust the idle speed around 750 rpms in forward gear. It never hurts to run the slow air fuel a little rich it helps for cold starts and a good hole shot. Take it out and run it WOT for a bit and then go back to idle and final the slow needle adjustments. If you do it right you shouldnt have to touch the carbs until it is time for the next rebuild. For future reference when you rebuild the carbs the only parts you dont take out are the butterflys. Allways adjust/check engine sync and adjust the slow needles as necessary.
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Thank you for your reply. I think that mine are the early production, as they do not have drain screws on the bottom of the float bowls, as there are four screws that attach the float bowl to the Carbs and there is a drain screw on the lower front of each Carbs float bowl. When I did the rebuilds I removed these screws and sprayed carb cleaner through them.
 
But the 7/16" head screw is the drain screw for the carburetor.------------Also where you remove the high speed jet ( orifice ) for cleaning.
 
did you remove the soft plug, ther are a couple of very small holes under it that should be reamed clean, think the holes have some thing to do with idle/low speed
 
racerone said:
But the 7/16" head screw is the drain screw for the carburetor.------------Also where you remove the high speed jet ( orifice ) for cleaning.
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I removed the drain plug, and the paperwork said that there was an orifice in there also but I could not figure out how t get it out, so I just sprayed carb cleaner in it and used a small wire and ran it in and out a few times. After I put the carbs back together and hooked up the fuel lines, I pumped my primer bulb a few times with the carb drain plugs out and plenty of fuel came out.So I did not figure that there was a problem.
 
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