100hp 71 model trouble shoot ignition

toey77

Petty Officer 2nd Class
Joined
Dec 12, 2008
Messages
158
hoping some one can point me in the right direction for the best way to trouble shoot my ignition system... I am 90% sure I have a weak spark, I had the engine fire up and run for ten seconds and thats it.. I then took the plugs out and the spark was a thin line only.. so I went out and bought new plugs but it didn't change the spark quality and I haven't had any luck starting it since, (all done before I found this site) the motor has been sitting for years. I have owned it for 2 and had it fire when I got home then no more but I have bought a complete second motor for spares and hoping that this gets me through to a nice strong spark. but like most on here I am new to boating and on removal of plugs I was surprised to see they are completely flat from the electrode so I am not sure on how they make a good spark or what it should look like on this style marine plug it just looks weak to me. I did remove the amplifier after noticing the wires leading into it looked and were very brittle I tried to rejoin them as close as possible to the amp unit but I don't think it was good enough.. it is still producing the same weak looking spark, hence the reason for the second motor because when I rang the boat shop for a new amp and wiring loom (although my loom does seem good and the amplifier has "reco 1985 $180" writing on it) he said I cant get a new loom and a new amplifier was about $600 aus, but he said he has a complete motor that was taking off a boat for reasons he didn't ask cause he was asked to replace with a new one, with and I quote "a good amp and loom" although the loom seems the same as mine, it also had power tilt and good prop (props stuffed) so at this stage parts are no issue just some iboat knowledge is needed on the best way to trouble shoot it and where to start and a wiring diagram would be great... I have some experience on motors and 2 stokes form dirt bikes

Ohh and before I get replies saying he ripped me off to get rid of his rubbish this is a local dealer with a very good reputation and is very helpfully to anyone that walks through his doors. He also sold me the motor for $400 aus plus engine stand and a week later I found a running one on ebay for $400. but it was 4000 kilometers away lmao:rolleyes:
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: 100hp 71 model trouble shoot ignition

You can get excellent troubleshooting information from an original factory service manual. Contact Ken Cook Co., in Milwaukee. Or, you can try cdielectronics.com for ignition help. I run the flat tipped plugs in my engine and they work great. Many of these earlier engines use them.
 

toey77

Petty Officer 2nd Class
Joined
Dec 12, 2008
Messages
158
Re: 100hp 71 model trouble shoot ignition

Oh no, tell me you didn't paint that cowl before getting it running well! You jinxed yourself big time!!!! :p There's a reason mine still looks like this http://i176.photobucket.com/albums/w200/ezmobee/New Boat/DSCF2640.jpg

i am a spray painter by trade so painting that cowl cost me nothing but a few hours of my time and making it look good was to give me the motivation to get back into my boat project. so all in all its fine if i cant get the motor up and running the wife will kill me for spending $400 bucks on the second motor not for painting the cover:D
 

toey77

Petty Officer 2nd Class
Joined
Dec 12, 2008
Messages
158
Re: 100hp 71 model trouble shoot ignition

You can get excellent troubleshooting information from an original factory service manual. Contact Ken Cook Co., in Milwaukee. Or, you can try cdielectronics.com for ignition help. I run the flat tipped plugs in my engine and they work great. Many of these earlier engines use them.

I would love a service manual but until I get the thing running the wife wont like me spending more money on it I am feel the same, plus i told her if i bought a second motor i will have all i need to get it up and running:rolleyes:
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: 100hp 71 model trouble shoot ignition

Check the CDI troubleshooting guide on the web.
 
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