1987 johnson 40 hp was running and now is not!

[Waterfowl_07]

I have a 16 foot mirrocraft with a 1987 Johnson 40 hp (Model # J40TLCUD).

My friend and I recently resealed the lower unit and I took it out on a test run to see if it stopped taking on water in the lower unit (which it did). But while I was out there I had the boat at full throttle and it would run good and then bog down then instantly run good and then bog down and kept that up pretty much until I returned to the dock. I brought it home and pulled and cleaned both carbs and reassembled it.

The problem I have now is that it would start but the only way to keep it running was to keep squeezing the primer bulb on the fuel line, we were trying to figure that problem out when the engine eventually would not start, it will crank but not start. Even when we bypassed the carbs and went through the spark plug hole with carb cleaner (I know prob not the best thing to do) it just cranks but wont fire up at all, and tested both spark plugs and they were good and I even went out and bought new ones but still the same dillema...

Additional info: This boat does not have a kill switch (previous owner removed it I guess)

Also This boat was converted from VRO to pre-mix

Any Ideas as to why it no longer starts would be greatly appreciated, Thanks in advance.

 

[fireman57]

Re: 1987 johnson 40 hp was running and now is not!

when you pump the primer bulb does it get hard? Squeezing the primer bulb and it keeps running indicates a bad fuel pump but it should at least run until the carbs get empty. If you are going to put anything in the spark plug holes use premix. If it ran before you cleaned the carbs and now it doesn't then I would take another look in the carbs. Make sure your floats are set level when turned upside down and make sure that all orafices and jets are cleaned with a small wire run thru them and then blown out good. If you say your plugs are good that is one thing but when you check for spark you need a spark tester that will show how far the spark jumps. It needs to go almost 1/2" and be bright blue. The black and yellow wire is your kill switch, make sure that it is not grounding out somewhere.

 

[Solittle]

Re: 1987 johnson 40 hp was running and now is not!

Also check for bad o rings at the fuel connectors - - air in the fuel lines.

 

[Waterfowl_07]

Re: 1987 johnson 40 hp was running and now is not!

Thank you both for your responses! I finally got it back up and running last night, after checking all seals, o-rings, etc, and taking apart the carbs again among numerous other things. The culprit was that little red lever on the starboard side of the motor that is connected to the choke solenoid (not sure on terminology there) that allows gas to pour into your carbs when you have the key pressed in. That lever was turned to the left (9 o'clock position) when it should have been turned to the right (3 o'clock) position. anyways i was flooding the engine as if i had the key pressed in even when I didnt.... but thanks to all your help!

Sorry for any typo's etc, Its early and I'm going Fishing!!

 

[Waterfowl_07]

Re: 1987 johnson 40 hp was running and now is not!

Ok so I got my boat out on the lake thinking I had fixed my problem and was good to go and when I went to take off it did not have full power... just bogged down. I could still put around to chase stripers and kill and start engine over and over again with no problem, but I just could not get it to get up and go.

I had my friend pull the cowling off while we were moving at a slow speed and flip that red lever back to the left ( that was causing the flooding in my initial problem) and the motor would take off and run fine, but if I idled back down it would flood engine and die. So I know that the motor is starving for fuel, and was thinking that the high speed jet in carb (or both) is clogged but I just took them off and inspected them last night and looked good and once I got it put back together and started it, it ran perfect on the trailer last night, just not the next morning in the lake!

I have searched online for this answer and have found forums where people have had same issue with same motor but there was no solution to the problem..

Any ideas would be greatly appreciated! Thanks in advance