1966 Johnson Outboard Runs great with rabbit ears on but won't run in the water?

Question

We just got a boat and in the driveway with ears on it runs great, but as soon as we put it in the water to go it either won't start, or when put in gear it dies. When running in the driveway if I cover the middle carb it will die I can cover the top and the bottom carb and it stays running. I have already cleaned plugs but not replaced, changed gas lines, checked gas tank filter, and changed the lower unit oil.

Any suggestions would be great.

Answer 1

Are you running in the driveway with the cover off?

If so check where your fuel lines are when the cover is put on. You could easily be pinching a fuel line when the cover is on and put in the water.

Answer 2

cheapest thing to do 1st is install new spark plugs

Answer 3

I guess this is a 60 or 65 HP motor?

Very common.  because you have underwater exhaust, which puts a load on the engine when the prop is submerged, while in the driveway it's completely unloaded.  It'll easily run on two cylinders, maybe even one.

Before you spend any money, take a few minutes to do some basic tests, that way you only have to fix what's broke.

Compression test:  no sense spending time or money on an engine with bad compression.  Should be about the same on all cylinders (within 5% or 7%).

Spark test, not a *spark plug* test.  You're testing the ability of the ignition system to deliver a spark to the plugs.  Get an inline tester (couple bucks at a car parts store), set the gap for 1/4", clip it to the engine block, attach the plug leads (one at a time) and watch for a strong blue spark when you turn the engine over.  Get bad or no spark on one or more cylinders, you'll have to troubleshoot the ignition system.

If you have good compression and good spark, on all three, make sure you've got fresh 87-octane fuel mixed 50:1 with TCW-3 certified oil.  Make sure the primer bulb gets and stays firm when you pump it up.  Make sure the the choke plates all close completely when the choke is activated.

All this and still no go, rebuild the carbs with new kits.  Soak the metal parts overnight in carb cleaner.

Compression, spark and fuel, she oughta run.

Answer 4

You say that the spark plugs are wet which means the needle

and seat in your carbs are stuck open.Try cleaning them and

install new spark plugs and then run it again.Good luck.