My Johnson Outboard wont run in the water but runs great on the water hose.?

Question

My boat run great on water hose , but under a load in the water it's hard to start and keep running.

I've replaced the fuel pump, carbs were rebuilt, new jets, no obstructions in the water pump system(good stream of water).

Quick history: The boat repair place has had it for a month messing with it and still cant figure itout( yes Don't say it) THEN GO PICK IT UP.

I've already paid them for the Fuel pump, Carb. work, New jets for the card.

I took it to them in the beginning cause the motor "Burpped" at high speed.

Please help with your ideas...

Answer 1

It could be an electrical problem with the ignition not advancing when the throttle does. That could be it or any other host of things. Watch the throttle advance and ignition and see if it bogs down then. Ask the technician if that could be the problem. They can usually figure it out.

Answer 2

hmm  good one what i would do is change the fuel filters and water sepperator if you have one, also is it pissing water out the tube when running on land? if not change the water impellor and change the plugs  try that than you might have to get a johnson repair shop but not the one you are using and let them figure ir oue

Answer 3

what is the compression onthe cylinders?

if you got less than 110psi compression, you need new rings.

that's what it sounds like to me.

Answer 4

Did you do a compression check ? what size/year is the motor ?

Answer 5

difference between the hose and in the lake is backpressure on the underwater exhaust.

did those parts-changers down at the boat place do a compression test and spark test?

If not, do that first.

Compression should be about the same on all four.  Anything over 90 would be good on that vintage v4.  Spark should jump a 7/16" gap on an inline tester.

Is the primer bulb getting hard and staying hard?

Take the airbox cover off.

Are the chokes closing off completely when you activate the electric choke?

Tilt the motor full up and pump the primer bulb until firm.  Does any gas leak out the carb throats?

Are the spark plugs wet or dry after cranking?

Are they champion QL77JC4 gapped at .030?

Is the battery fully charged?  it needs to crank at least 250 RPM to start.