justa150merc
Cadet
- Joined
- Jun 24, 2014
- Messages
- 24
Good evening guys,
So I have a '76 Merc 9.8 that's in fantastic shape for its age. I bought it a year ago for $400 and have it really as just a small hobby motor that I occasionally throw on my great grandfathers old 12 foot boat and go bomb around the lake for a bit. I love old kiekhafer mercs!
Anyways, my problem is that during idle or lower throttle positions, the motor occasionally drops a cylinder and runs on one, but then as I start to increase the throttle, either slow or fast, the 2nd cylinder kicks in and it runs great everywhere from 1/4 throttle to full throttle. Hell, I get 22 mph out of her with myself and 3 gallons of fuel. It runs fantastic and always on 2 cylinders anywhere above roughly 1/4 throttle.
Once I get under 1/4 throttle, it's anyone's guess as to when it kicks out a cylinder again, sometimes it's right away, other times it runs on 2 for 5 minutes of low throttle then randomly kicks to 1.
I have checked to see which one is giving me issues and it appears to be the upper coil, if I pull that plug wire it runs on 1, if I pull the bottom wire it won't start. This is when it's going through its 1 cylinder routine. Like I said, sometimes it runs on 2 just fine for 5+ minutes.
I also hear a weird clicking noise with the cowl off when it kicks into 1 cylinder as though it's arcing and grounding somewhere??
Any thoughts would be great! I just bought a whole new (used) good working ignition system from a parts motor 76 9.8 that comes with coils wiring hardness etc. I'm thinking it's just a bad coil, but it's weird that it runs so good anywhere besides that 1/4 throttle and below. I can run it at WOT for 10 minutes and it doesn't miss a beat, same for other throttle positions besides 1/4 or lower. Thoughts????
Thanks again.
Background:
- always use 91 non E fuel with stabil mixed at 50:1 with pennzoil premium plus.
- carb is clean and adjusted
- brand new impeller that pumps water perfectly. Confirmed the motor is cooling properly.
- plugs were brand new last year
So I have a '76 Merc 9.8 that's in fantastic shape for its age. I bought it a year ago for $400 and have it really as just a small hobby motor that I occasionally throw on my great grandfathers old 12 foot boat and go bomb around the lake for a bit. I love old kiekhafer mercs!
Anyways, my problem is that during idle or lower throttle positions, the motor occasionally drops a cylinder and runs on one, but then as I start to increase the throttle, either slow or fast, the 2nd cylinder kicks in and it runs great everywhere from 1/4 throttle to full throttle. Hell, I get 22 mph out of her with myself and 3 gallons of fuel. It runs fantastic and always on 2 cylinders anywhere above roughly 1/4 throttle.
Once I get under 1/4 throttle, it's anyone's guess as to when it kicks out a cylinder again, sometimes it's right away, other times it runs on 2 for 5 minutes of low throttle then randomly kicks to 1.
I have checked to see which one is giving me issues and it appears to be the upper coil, if I pull that plug wire it runs on 1, if I pull the bottom wire it won't start. This is when it's going through its 1 cylinder routine. Like I said, sometimes it runs on 2 just fine for 5+ minutes.
I also hear a weird clicking noise with the cowl off when it kicks into 1 cylinder as though it's arcing and grounding somewhere??
Any thoughts would be great! I just bought a whole new (used) good working ignition system from a parts motor 76 9.8 that comes with coils wiring hardness etc. I'm thinking it's just a bad coil, but it's weird that it runs so good anywhere besides that 1/4 throttle and below. I can run it at WOT for 10 minutes and it doesn't miss a beat, same for other throttle positions besides 1/4 or lower. Thoughts????
Thanks again.
Background:
- always use 91 non E fuel with stabil mixed at 50:1 with pennzoil premium plus.
- carb is clean and adjusted
- brand new impeller that pumps water perfectly. Confirmed the motor is cooling properly.
- plugs were brand new last year
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