I HAVE A 1979 85 HP EVINRUDE BOGGS DOWN

Question

THIS ENGINE RUNS GREAT OUT OF THE WATER WHEN IT IS HOOKED TO THE WATER HOSE. WHEN I PUT IT IN THE LAKE IT JUST BOGGS DOWN WHEN I TRY TO TAKE OFF. I HAVE FOUND TODAY THAT ONE CYLINDER IS NOT FIRING. IS THIS MY PROBLEM? WHY WILL IT RUN GOOD OUT OF THE WATER BUT NOT IN THE WATER??

Answer 1

when the lower unit is submerged, backpressure on the exhaust puts a load on the engine that isn't there when its running on muffs.  it'll run and sound great on three cylinders, till you put a load on it.

Assume by "not firing", you mean no spark?

swap the ignition coil from the dead cylinder with one of the others you dont' have to take 'em off the engine, just rearrange the orange wires, and check it again.

if the problem follows the coil, replace it.

problem stays with the cylinder, swap the powerpacks (two on that motor, one for each bank).  problem follows the pack, replace it.

problem stays with the cylinder, you'll have to troubleshoot the timer base & stator  --  probably won't get that far but if it does, just ask.