1972 Johnson 100 HP Starting problem

" Hi-

I recently purchased

" Hi-

I recently purchased a 1972 Larson with a 100 HP Johnson. I decided to change the lower gear oil before taking it out. I used "type C" gear oil for engines with electronic shift. After changing the oil I fired up the engine. It ran fine for 30-60 seconds, then stopped and won't start again. I've checked the fuel line and there seems to be plenty of gas getting to the motor. Is there any way that changing the gear oil can effect the way the engine runs in neutral? Any other ideas?? Thanks for the Help!! "

" Changing the gear lube has n

" Changing the gear lube has no effect such as you mentioned. When problems such as this happen, the first thing to do is check the compression and ignition. The compression should be in the area of 100lbs and even on all cylinders, or varing not more than 3 or 4 lbs. The spark (with the s/plugs out) should jump a 1/4" gap at the rubber boot on all cylinders. The 1972 100hp Johnsons have a terminal block at the top of the exhaust baffle plate area, between the cyl heads. On that terminal block, there will be a "Purple" wire that leads to the powerpack (that black box you see there). With the ignition key in the "On" position, there should be 12 volts at that "Purple" wire terminal. Check the above out and get back to us with the results. (Joe - 30 years with OMC) "

" Thanks Joe for the help. I

" Thanks Joe for the help. I was finally able to get to it this weekend. The electrical and compression were both fine. I traced the problem to the fuel line and it seems to be running fine now. A new problem is that the switch in the throttle box that activates the hydroelectric solenoids is broken, so the boat can't be shifted into gear. Can you recommend a supplier for this part? Thanks! "

" That's going to be a tou

" That's going to be a tough one. It's been unavailable for quite a number of years now. I thought I had one left in stock but it's not under file. I'll check farther and if I locate it I'll get back to you. The only suppliers that I can think of right now would be any Evinrude or Johnson dealer who might have one left in stock, or has some old used items. I believe the OMC part number for that switch is #383620 if it's the toggle type switch. The only other route to take that I can think of is to rig up a couple toggle switches on the dash whereas power is fed to both the green and blue wire for reverse, and to the green wire only for neutral. Forward gear requires NO power applied. (Joe - 30+ years with OMC) "

" Good news! I was able to lo

" Good news! I was able to locate a new switch at the local Johnson dealer--- their last one(#385253). I guess next time, I'll have to go with the toggle switches on the dash. Thanks again for your help. "