Question regarding boat throttle and motor repair.

Question

My boat idles way to high when started. My boat will not consistently plane out, why? Sometimes it runs fine, but lately and more often will not plane out. I have a Johnson 70hp motor (2-stroke).

Answer 1

What year Johnson? Does it have the "fast-start" feature? To cold start a fast-start motor, you don't lift the hi-idle lever; all others, you lift the lever full up to the "start" position.

The idle at start-up and the bogging might or might not be related.

Start with some basic troubleshooting:

Does the fuel line hold pressure?

Are you using fresh fuel?

Check the tank for water and/or debris

Are all three throttle butterflies closed at idle, parallel, and perfectly horizontal at WOT?

Are you using Champion QL77JC4 gapped at .030?

Fuel tank vent open and clear?

Compression test -- should get about the same PSI on all three, within 10 lbs or so

Spark test -- not a *spark plug* test. Use an inline tester (couple bucks at autozone), set the gap for 7/16", look for a sharp blue spark.

Report your results.

Meanwhile, don't run it like it is (except for testing) -- if any cylinders are starving for fuel, they're also not getting any lubrication.