I have a johnson GT 100 on a 16ft bassboat and it wont get on plane?

Question

When there is weight in the front it will get on plane and run but you should't have to do that it should have the power to get out the hole

Answer 1

If it's been like that since you got it, it could be overpropped, or the boat could be waterlogged, or the hull might have a hook.  Especially if its an aluminum boat and the bunks don't go all the way to the end of the transom.

Does the fuel line hold pressure?

Is the tank vented and free from water and debris?

Are you using fresh 87 octane gasoline?

Or, it could be one of 3 things:  bad compression, inadequate spark, or fuel starvation.

Do a compression test;  the lowest should be within 5 or 7% of the highest.

Then a spark test, not a "spark plug" test.  You should get a sharp blue spark across a 7/16" gap on an inline tester.

Spark plug should be champion QL77JC4 gapped at .030

If compression and spark check out, rebuild the carbs.  Soak 'em overnight in carb cleaner, remove the core plugs & blow through all passages with compressed air (or aerosol carb cleaner).  Reassemble with new carb kits.  Reinstall, link & sync, adjust slow speed mixture screws (if equipped).

DON'T run it like it is -- any cylinders starved for fuel are also not getting any lubrication.

A decarb will help, read about here:

http://forums.iboats.com/showthread.php?...

Answer 2

That is an open question. Either your engine is not putting out 100hp or their is to much weight in the back of the boat. Have the compression checked. Make sure there is no hidden water under the floor.

I could see where you would have 2 guys, 2-3 batteries, 20gl of fuel and the engines, that would be allot of weight for a 100 to push.

Please add some more details. Are you new to this boat?

Answer 3

It needs a tune up so swallow hard and spend the money.

Answer 4

If there is nothing wrong with the motor, then you need a prop with a smaller pitch.  Example, if you have a 17 pitch prop, try a 15.  You will lose top-end speed, but at least you will be able to get out of the hole.