1975 70 hp idle issue PLUS coil issue

[redneck bubba]

Hi- I have a 1975 Evinrude 70hp. I just bought the boat a few weeks ago and took it out for the first time. At first it ran kinda rough at idle but cleaned up a little. As I left the dock it climbed fairly well but would not plane and just didn't sound quite right. after about 2 minutes it cleaned up too and gained 7-8 mph and planed excellent. We rode for at least 45 minutes at higher cruising rpm and she did excellent. As we came back to the dock it just would not idle at all. Nothing we did made a difference. I brought it home and this is what I've done- Put correct plugs in, removed airbox and drained carbs(also sprayed carb cleaner in bowl to flush out any contaminants), cleaned factory screen filter and added an inline filter, took both tanks out of boat and drained all gas and cleaned out real well,checked over everything and it all looked good. I have fresh fuel, Starbrite and Seafoam additive, and good quality 2 stroke oil. Heres where I do have a problem and I want to make sure its fixed before trying again. My middle coil appears to have some type of adhesive/sealant where the wire goes into the coil. This wire pulled right out when changing the plugs. I see replacement coils with the wire NOT already attatched and those WITH it already attatched. Do I have a problem or can I just push the wire back inside real good and put something there to keep it in place?

 

[emdsapmgr]

An intermittent problem can be an ignition problem. It's possible that your coil in question is not functioning properly. Usually these coils last for a long time, but they can go bad with age-and if you happen to catch the coil wire with the cowling latch each time you replace the cowling on the engine. You can test for spark. Do it when the engine is under load. Put the boat in the lake, run it at idle in forward gear. Put an inductive timing light on each plugwire and note the flashes from the gun. They should be strong, rhythmic-that's normal. If you see intermittent, weak flashes, it may indicate a problem with ignition to that cylinder. The original coils on that engine had the coil wire as part of the coil-permanently attached. Todays' replacement coils are updated and have a removable coil wire. They are not overly expensive. Do some testing and replace the coil based on your findings. I'd be inclined to replace it, based on your description of the loose plug wire.

 

[fireman57]

Also that engine will idle on two cylinders and sound fine but your isn't. You really do need to dismantle your carbs and make sure all the jets are clean.