[kwhitted]

91' Yamaha C115 V-4I've read many of the Starting topics and have some clues but I need to narrow down a bit more. Symptoms are generally very difficult to start after it has set for awhile. Crank, crank, crank, flooded, pull the plugs, clean them up and try again.The other day while doing this I checked for spark. While grounding the plug on the engine and cranking there was no spark. Did this for about 8-10 seconds with no spark. But then a little spark jumped across the electrode and the same time the engine fired. I put the one plug back in and it cranked right up. Once it starts and run to the bay (about 10 minutes) it will start instantly and run great the rest of the day with many subsequent starts by just a brief touch on the starter.Today before I left the house I tried cranking it. It popped a time or two but would not start. After a few attempts it would not fire at all. Flooded. Pull plugs and clean. I check for spark but get none on all 4 plugs. Went to the boat ramp anyway. When I tried to crank no fire. I tried with several different choke and throttle settings. Nada. Except one. I had not tried FWOT. So I pushed the throttle all the way down with choke and tried. It popped once but no more. So I got this idea and pulled the cover. While cranking I had my son tap the powerpak with a knife handle. He barely got the second tap on it when it roared to life.So we take off but dont get more than 1/2 minute from the dock running fast when it just dies, like the key turned off. Crank, crank, nothing. Pull the cover and crank while tapping the powerpak. Its firing but not starting. Push the throttle all the way down, crank while tapping and it starts. We continue to the bay. It runs fine for the next 4 hours. The engine would be off for periods of as much as a half hour but would start up with no hesitation at the touch of the key. Did this probably 7-8 times.This problem has gotten progressively worse over the past year or so. My thoughts are something to do with the powerpak, coils, stator, or rectifier. It would seem that maybe there's a short and the tapping triggered it or it may have had something to do with pushing the throttle all the way. I notice that moves some linkage underneath the flywheel around the stator area. Just dont know. There's too many possibilities in the electrical system . I even read where kill switch or bad grounds can do it.If there's some simple troubleshooting steps I can do to isolate would like to try before dragging it down to Yamaha shop. Thanks in advance for any help.K-ManSeabrook TX

[jim dozier]

Check for loose or corroded connections in the ignition. I am assuming you have already replaced the spark plugs.

[Capt Ken]

The only electrical problem I've ever encountered with the V4 Yamaha is the CDI. If I was to bet money, I would say that it has given up the ghost. You can remove the cover and disconnect the white wire at the lower left corner and see if it sparks OK then. That's the main kill wire that goes to the key switch. If it runs fine with the wire disconnected, then you have a problem elsewhere. I've never seen a stator or trigger assembly give problems on these units.

[kwhitted]

UPDATE... Been sitting over a week. This morning I pump the gas bulb til firm, choke, with throttle all the way down, crank and it fires right up immediately. While running I start pulling off plug wires to see if the engine sound changes. The top left (viewed from behind) wire bit the hell out of me. Put on gloves. Definitely fire on that one. Lower left does not appear to have fire. Sound does not change and cannnot see/hear any spark jumping across from wire to plug. The two on the right were hot. I continued to check and tried to use my volt meter to check but I think its not the right type (peak volt meter?). Funny thing while doing all this. That upper left that bit me good while checking again I notice the spark would flow freely right out of the end of the rubber plug boot. None of the other would do that. Another weird thing. After the engine had been running for a few minutes when I checked the lower left again it now seems to be firing. I can hear the clicking of the spark and when I disconnect the engine stutters a bit.Checked all wiring connections inside the CDI cover. All clean as a whistle. Disconnected white wire but reconnected with gator clip test lead, started engine, pulled the white wire off, engine keeps running, turn off key, engine still keeps running, reconnect the test lead to terminal in the CDI box, engines stops. This may be significant I think. There have been times when after running the engine for awhile I turn the key off and the engine keeps running. I would have to pull the manual choke to kill the engine. Could this be a bad key switch assembly? Please say it is. I know they must a fraction the cost of a CDI.Many Thanks AmigosK-ManSeabrook TX

[kwhitted]

Anyone got any input on my last post? I'm hoping I'm getting close to narrowing this down. ANy help is most appreciated.K-ManSeabrook TX

[Knightgang]

I am not sure what the actual problem is, but I can tell you that the cost difference between a Key Switch and a CDI unit are significant as you say. It might be worth paying the $20 for a new switch just to see if that fixes the problem.