1983 14o hp Johnson powering down

[florist2]

I bought an older boat last year, the motor is a 1983 v-4 140 johnson outboard. Had it in the water and it ran good for a short while. then it seemed like it just bogged down. Or powered down I guess you could say. As you can tell I know nothing about this. Way out of my league, So I figured I would ask here and see if I might find out what it could be before I took it too yet another mechanic. The last one checked everything and said the only thing he could fine was a thermosat issue.. which he replaced, that cost me 300.00. We put it in the water and just like before. Its starts ok and runs ok. Powers up well. Then all of a sudden while crusing along it just seemed power down and even with the throttle wide open it would go no faster. I took it back to the same guy another 200.00 for some repairs. Tried it again and still the same thing, he then said it would be best to take it to someone else. I thought to myself. You are right. Duh. LOL And this is how he makes a living. So yes I am a bit reluctant to deal with theses guys. I parked it. Now So yea I wanted some type of idea as to what the problem might be before hand.. Below is what I was told had been done by the mechanic. replaced right head gasket and thermostats, left and right power packs checked and cleaned grounds on coils and power packs..any ideas??? someone said maybe the wiring shorting out? IDK

 

[Bosunsmate]

Re: 1983 14o hp Johnson powering down

You have being given some bad expensive service there.

You say it starts and runs ok at what i think is idle. Is there any backfiring at idle?
Can you put your hands on the head when it bogs down or does it feel very hot?

It may be a failing waterpump, or stuck poppet valve or something causing water to not circulate properly causing it to overheat at higher rpm.

You could buy a spark tester, they are only a few dollars and check you have good spark on all cylinders. Sometimes they will go ok at idle but fail at faster rpm, a spark tester can pick that up.

Also check none of the linkages have come off, my 1982 did the same thing the other day, bogged down and wouldnt go any faster even with the throttle right down. Ended up being just a linkage coming lose off the throttle on the side of the motor

 

[emdsapmgr]

Re: 1983 14o hp Johnson powering down

You can do a simple fuel pump test. When the engine bogs, have someone constantly prime the fuel hose bulb. This will force extra fuel into the carbs. If the engine picks back up and runs fine as long as you constantly prime the fuel hose bulb-then you have a fuel delivery problem. That could be anything from a bad hose, to a weak fuel pump, etc. If that makes no difference, then check for good spark. Weak ignition components tend to run fine when cold, then crap out when the engine heats up to normal operating temps. Two good tests, a cyl drop test or you can use an inductive timing light to check for spark. When the engine slows, put the timing light lead on a plugwire. The flashes from the gun will show the spark. Compare the flashes from the gun with all 4 plugwires. You will be able to determine good spark, no spark, weak spark, intermittent spark. That engine has dual matching power packs-one for the spark on each head. If you find no spark on one plug, swap the power packs and see if the "no spark" condition moves to the other head. If so, replace the bad pack.

 

[florist2]

Re: 1983 14o hp Johnson powering down

You have being given some bad expensive service there.

You say it starts and runs ok at what i think is idle. Is there any backfiring at idle?
Can you put your hands on the head when it bogs down or does it feel very hot?

It may be a failing waterpump, or stuck poppet valve or something causing water to not circulate properly causing it to overheat at higher rpm.

You could buy a spark tester, they are only a few dollars and check you have good spark on all cylinders. Sometimes they will go ok at idle but fail at faster rpm, a spark tester can pick that up.

Also check none of the linkages have come off, my 1982 did the same thing the other day, bogged down and wouldnt go any faster even with the throttle right down. Ended up being just a linkage coming lose off the throttle on the side of the motor

Not sure if the head was hot or not.. had no idea that I should check it.. I was just praying we would make it back to the boat ramp, and we did. slowly but surely. I,ll check the linkages. I think the spark plugs/ spark was checked but. I will check it again. Water pump. you say? well there I would be at a loss there. Not idea how to check that. You see guys I didn't check anything because I Knew that I knew nothing about these motors.. Thats why I was just happy to get back in and take it to someone I thought knew what they were doing. and yea I plan to check the fuel lines and pump too. thanks guys and I will see about these things you guys suggested.

 

[71Windsor]

Re: 1983 14o hp Johnson powering down

Friends motor did the exact same thing. Once we put it in a deep tub of water removed the thermostats and ran it we found almost no water making its way up to cool the engine. Dropped the lower unit and found multiple fins missing on the water pump.