Having trouble with an older Johnson GT 150

[dj_callahan_27]

I have a 1984 Procraft 1750 bass boat with a Johnson GT 150 motor. The motor isn't running right. After you start it and idle it up to let it warm up it still will not idle at the lower rpms. Then when you do get it in gear and have to idle out of the no wake zone it's like it loads up and it will quit if you don't speed up and once you do get out of the no wake zone and open it up, right brfore it planes off it fills like it is missing and don't have the power to get up on plane. On the other hand, if you stop the boat out on the lake and give it a few min. before starting it back and can go without having to idle much the boat will jump up on plane and get gone in a hurry. Any insight on this problem would be helpfull Thanks DJ

[dj_callahan_27]

I don't know where to find the model or serial # for the motor but I did find this on the block of the motor RSM6412V and this below it 85 150 S and this below that 8 24 92. Hope this helps. If this isn't what you need where would I find the # you need?

[Bassmeister]

Try looking on the mounting bracket,leftside.

[dj_callahan_27]

Thanks I'll check there

[ChampioNman]

Got a guess on the model year of the motor? The model number on the tag will tell for sure.

[dj_callahan_27]

Ok I found it. The model # J150STLCRD I think the last two ( RD ) was hard to read And the serial #J5969441

[ChampioNman]

It would be an 84.

[dj_callahan_27]

Thanks alot. I knew it came with the boat but wasn't such of much else. I don't know what I should do to try to fix it though. I was thinking of ordering carb kits for it but would really like some more input on it before I buy something that wouldn't help.

[dj_callahan_27]

I was thinking it might have a bad coil pack but after pull all the spark plugs out and checking to see if they were firing. They was so I think I can rule that out. So right back to square one. Don't know if carb kits will help or maybe just cleaning the carbs. But if I go as far as to clean the carbs may as well get the carb kits I guess. Oh well just spinning my wheels trying to figure this thing out. Any and all help would be appreciated.

[dj_callahan_27]

Anyone have any ideas?

[ChampioNman]

Try this when you are idling out of the no wake zone, trim your motor up some and see if it idles OK. If it does inspect the recirc valves, also check head temps with a IR gun or a thermo stick.

[DoferGofer]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dj_callahan_27 &raquo;</TD></TR><TR><TD CLASS="quote">Anyone have any ideas?</TD></TR></TABLE>

Recirc valves are one-way valves and there is a procedure in your repair manual describing the correct way to test your valves without doing damage. New recirc valves cost approximately $11.00 - $12.00 a piece.
Therefore, use due care when inspecting or testing your precious valves. Also, make sure the recirc hoses are in good shape or just replace them.
As persnickety as I am, I just replaced all of my recircs valves and hoses when I revived my engine after being unused for a brief 15-year period. Incidentally, my engine will idle “ALL DAY LONG” without a whimper from idle to WOT. I would suggest you purchase an overhaul/service manual for your engine and read, read, and re-read. &lt;smile&gt;



Regards,

[dj_callahan_27]

I don't have a manual for this motor, but soulds like something I should check into. Thanks for the help. I was told on another forum to try Seafoam. Just add it to the gas and run the fire out of it until the gas was gone. It is supposed to burn the carbon out of the motor and carbs. Any thoughts on this product?

[Bassmeister]

We recommend the BRP 2+2 fuel conditioner, however many people have used the other products with out complaint.

[Mark Wendler]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ChampioNman &raquo;</TD></TR><TR><TD CLASS="quote"> .................also check head temps with a IR gun or a thermo stick. </TD></TR></TABLE>

Wise words!!!! Had the same symptoms until my motor "doc" checked the head temp. Seems a stuck thermostat will cause these motors to "load up" easily when idling.

[DoferGofer]

I use Seafoam religiously in all of my gasoline engines. I feel it is a good preventive maintenance aid but not a wrench in a can.
Again, I suggest that you follow the ChampionNman's suggestion as a starter; if that does not solve your problem then, there are many more systematic tests we can follow in a good manual for your particular engine . . . and suggestions from the pros here on BBC.
Remember, there is not any "Wrench" in a can that can work miracles on your engine, just good preventive maintenance.



Regards,

[gearcaseman]

Sounds like you may need to check the float level adjustments in the carbs. Also make sure your sync & lync are correct.