Johnson 150 surging

[Jim Rider]

I have a 2000 Johnson 150 engine that is not fuel injected. When I took the boat out for the first trip this summer the motor ran good but would surge in RPMs while going across the lake. The increase in RPMs would be about 300 -400 RPMs for a few seconds and then it would drop back to normal. It felt like someone had just pushed the throttle forward and then let off after a few seconds. Any ideas??? <br /><br />Thanks<br />Jim

 

[SAGE9]

Re: Johnson 150 surging

Hi Jim - sorry for doing this to you but you have the same engine as I do/will have. I had an early post about this engine emitting a lot of smoke and a strong gas odor and even leaving a pretty good sheen in the water when sitting idle. Do you have the same experience with your engine? It just seems much stinkier than other engines.<br /><br />And to answer your question...I have not yet experienced any surging. Good luck with that though.

 

[Jim Rider]

Re: Johnson 150 surging

My motor does have some smoke on start up, but I think that is probably to be expected with a 2 cycle carburated engine. I have not seen an excessive amount of oil on the water when it is idling. The motor runs very good but seems to be very hard on gas. The smoke on start up is only evident on the first start up of the day.<br />Jim

 

[SAGE9]

Re: Johnson 150 surging

OK - hopefully it was all the winterizing stuff coming out! Thanks.

 

[Jquest]

Re: Johnson 150 surging

Check your spark plugs wires and make sure they're tight. You might be dropping a plug. You can also purchase a spark plug tester at autozone and check to see that you have spark in all 6 cylinders.

 

[sikpnter]

Re: Johnson 150 surging

Do you feel the boat go faster or just the motor reving up? If just the motor is reving could be hub in prop slipping.What are your rpms when this happens?

 

[Jim Rider]

Re: Johnson 150 surging

Boat definately speeds up when RPMs increase at motor surge. It feels like somebody just nailed the throttle.......<br /><br />Jim

 

[Jim Rider]

Re: Johnson 150 surging

Sikpnter;<br /><br />This was occuring with the motor running at about 3500 RPM and the surge was 300-400 RPMs more for a second or two.<br /><br />Jim

 

[Bruce San]

Re: Johnson 150 surging

Just a thought and I'm no expert but, A lean condition will cause a short surge in RPMs. Running a 2 cycle lean is very hard on the internals as you lose lubrication with the loss of fuel. Check your hoses for cracks and leaks etc. where air may enter the system. Also be sure your gas tank vent is clear. As far as the fuel consumption goes...don't know what your used to but, V-6 carbed outboards are gas hogs.

 

[Walker]

Re: Johnson 150 surging

Sounds to me like you are dropping a cyclinder and it picks back up momentarily. First thing I'd do is clean all coil grounds and take a timing light on the lake. Try each sparkplug wire one at a time and see if one isn't dropping the spark when the motor starts surging.

 

[Jim Rider]

Re: Johnson 150 surging

That could be it and the surge happens when that cylinder kicks in for a few seconds. I would have thought though that it would be running really rough if it was running only on five most of the time. Do you think if this was the case that one of the plugs would look different if I pulled all six and looked them over? I replaced the plugs just before this trip out so they are all new.<br /><br />Thanks<br />Jim

 

[Walker]

Re: Johnson 150 surging

Plugs from a 2 stroke are hard to read. It might show but it might not. Won't hurt to take a look at them. One other thing you might check (I had this problem with a motor once) If the pee tube comes off the top of the block in the rear make sure its not leaking water onto a coil. Mine did but only at throttle and when I would pull the cowling I saw no wet coils, but the insulation on my cowling was wet. Sure your motor can run smooth on only 5.

 

[Jim Rider]

Re: Johnson 150 surging

I'll check that. I am making a list of things to check. I am headed to the lake for 9 days starting tomorrow so I can tinker with the boat over the weekend when the lake is too busy to fish.<br />Jim

 

[Melvin Hatcher]

Re: Johnson 150 surging

Don't overlook the powerpak.<br /><br />Regards,