Won't start/idle with lower unit submerged

[thrash]

Motor will run and idle normally out of water with ears on. When submerged at lake or in tub, hard to start, will not idle, and runs rough. What is the problem? Motor is a 1998 40 HP Johnson.

[Boobie]

What's the compression on it ??

[thrash]

No. 1 Cyl______118 dry 120 wet
No2 Cyl_______130 dry 133 wet

[boats.net]

When you are running at lake are the exhaust relief holes on back of exhaust housing under water, it wont idle if exhaust holes are under water. Is it firing and running on both cylinders?

[thrash]

It is firing on both cylinders however you might have me on the right track.
After consulting the manual my problem might be the reed valves are not closing properly?
what do you think?

[boats.net]

Usually if reeds are bad it will spit gas out throat of carbs when idling. The reeds can be seen by pulling carbs and looking in intake manifold.

[thrash]

Thanks for the reply, I will check out the reeds and let you know what I find out, thanks again.
May be a while we have over 100 degree temps.

[Joe Reeves]

********************
(Engine Won't Start or Hard Starting In Water)
(Joe Reeves)

The Evinrude and Johnson engines, starting in 1973, have what is called Magneto Capacitance Discharge ignition, self contained, not dependent on battery voltage. The engine must turn over at least 300 rpms in order for the flywheel magnets rotating past the stator ignition generating coils to supply approximately 300v AC to the powerpack(s), which in turn is needed to supply power to the coils etc etc (spark).

In the water, exhaust back pressure is encountered due to the fact that the exhaust housing (housing between the powerhead and the lower unit) is filled with water. This would drag down the needed rpms, affecting ignition.

Normally the clue to this type problem is that the engine starts fine on a flushette (hose), but is very difficult to start when in the water.

Should this be the case, check the battery, clean and tighten all conections (use a wrench or pliers, not your fingers). Any cable that gets overly warm or hot indicates either a loose, or tight but dirty, or internally corroded cable. And of course check the starter itself.

********************

[thrash]

Had a friend help me and we determined that the timing is BTDC 4 degrees, can not figure out why.