1989 johnson gt 150 not wanting to pass 3500 rpms

[basscat348]

This motor starts awesome, idles great,get's on plane right now,it has great acceleration up to about 3500 rpms then starts to bog down like it's dropping a cylinder or something,then i can return to lower rpms and the engine will run fine again.I have recently cleaned and rebuilt all carbs,added a fuel water seperator,and added another fuel filter hust before the fuel pump on the motor.What is the problem with this motor?Could it be the fuel pump not being strong enough to pull fuel through 2 fuel filters?Thats my guess.

 

[Joe Reeves]

Re: 1989 johnson gt 150 not wanting to pass 3500 rpms

Assuming that the warning horn beeps when you turn the key on BUT does not when this problem ocurrs, this would eliminate a fuel restriction problem. Do you receive any warning horn sound when this problem takes place?

If the fuel; primer bulb has a tendency to go flat, that also indicates a fuel restriction.

If you have proper compression and spark on all cylinders, possibly you're overlooking something within the carburetors. I find it a good idea to manually clean all the high speed jets with a piece of single strand steel wire..... solvent just doesn't seem to get those jets properly clean.

 

[basscat348]

Re: 1989 johnson gt 150 not wanting to pass 3500 rpms

There is no alarms when key is turned on or when this problem occurs.Now the horn itself may not be working either .I am going to change the fuel pump and take out that inline filter and go to the lake and test it.I will keep you posted.

 

[basscat348]

Re: 1989 johnson gt 150 not wanting to pass 3500 rpms

Ok so there is 1 chirp of the horn when I turn the key on.I took out the inline filter only leaving the 10 micron fuel water seperator.The boat ran awesome for about 2 miles,brought it all the way up to 5000rpm's no problem and thought problem solved.So on the return back to the ramp i was cruising at about 3000 rpm's when it starts acting up again and I checked the primer bulb when this is happening and it stays fairly firm the way its supposed to be.The only thing is I put brand new plugs in the motor this trip .Could the motor be getting to much fuel or something?I just dont know.

 

[basscat348]

Re: 1989 johnson gt 150 not wanting to pass 3500 rpms

Am I overlooking something but there doesnt seem to be any carb adjustment's on these particular carbs?

 

[jonesg]

Re: 1989 johnson gt 150 not wanting to pass 3500 rpms

Don't start twiddling with the carb settings, if they worked before and you didn't change anything the problem is elsewhere.

Do as Joe suggested, compression test and spark test with a spark gap tester set to 7/16th inch gap. Don't try to test the spark with a sparkplug, it doesn't work. Get a comprssion guage and adjustable gap tester at any decent auto part store. Don't buy the neon tester.

 

[Joe Reeves]

Re: 1989 johnson gt 150 not wanting to pass 3500 rpms

Basscat......... Reread the last paragraph on my initial reply.

Those high speed jets are in the bottom center portion of the float chambers.

 

[basscat348]

Re: 1989 johnson gt 150 not wanting to pass 3500 rpms

Spark gap tester awesome tool.Problem was 2 bad coils and 1 was pretty week.Thanks Guys.

 

[basscat348]

Re: 1989 johnson gt 150 not wanting to pass 3500 rpms

We'll the problem continues although its running alot better.The engine will get up and go to WOT like it should now but there is a hesitation that occurs after about 30 seconds , the rpm's will drop from 5000 down to about 4500 for about 5 seconds then it will go back up to 5000 rpm's for a few seconds,now it will run like this for however long you want to.It happens also in the lower rpms also,like 4200 rpm's it will drop to 4000 then back up.I have replaced port side powerpack all 3 coils and spark plug wires.I have cleaned carbs,added fresh gas and a fuel water seperator.Oh also while running when the problem occurs I have tryed pumping primer bulb and that has no effect.I'm stumped and I hate to admit it.

 

[Melvin Hatcher]

Re: 1989 johnson gt 150 not wanting to pass 3500 rpms

I would check the stator.


Regards,

 

[basscat348]

Re: 1989 johnson gt 150 not wanting to pass 3500 rpms

We'll the motor finally runs the way it should.The problems encountered in this whole process was bad power pack,bad coils on port side and ethanol had eaten away what looked like brand new fuel line's coming from the fuel pump to the carbs.They were just torn up inside .

 

[emdsapmgr]

Re: 1989 johnson gt 150 not wanting to pass 3500 rpms

Sounds like you have two power packs on your engine. You may want to recheck the model number on the engine. The 89 had a single power pack. The 88 and older engines had twin power packs.

 

[jonesg]

Re: 1989 johnson gt 150 not wanting to pass 3500 rpms

We'll the motor finally runs the way it should.The problems encountered in this whole process was bad power pack,bad coils on port side and ethanol had eaten away what looked like brand new fuel line's coming from the fuel pump to the carbs.They were just torn up inside .

You're lucky that fuel line could have blown the engine.
Alls well that ends well.