scout-j-m
Chief Petty Officer
- Joined
- Jul 31, 2009
- Messages
- 642
My motor is a 94 70hp. The motor starts easily and runs but it runs a little rough and sometimes at 3/4 to full throttle it cuts out a little and has surges in power. I've replaced the fuel pump diaphram, primer bulb, fuel lines, I have good gas with a can of Seafoam in it, and the tank is vented. I've eliminated a fuel problem from this and the fact that it sometimes runs without the problem occuring. I was baffled so I took it in to the mechanic. For starters, he found it had compression of 90, 110, and 110. He also said it had weak spark on two cylinders. He said something in the ignition system was failing causing the powere surges and that the low compression in that one cylinder added to the problem. I did a decarb at home but the readings stayed the same. I haven't done the oil in the cylinder yet to see if it is a head gasket, rings or the cylinder walls itself. I'd like to tackle the ignition system first though because I think the cylinder that's low on compression is also one with weak fire and the ignition system seems to be affecting the performance the most.
My question is how should I test the ignition system? Should I work my way from the stator and trigger down to the plugs or the reverse of that? I have the manual but it doesn't really deal with troublshooting the ignition. I feel that I can do it but I need to know what tools I'll need for the elctrical tests and what readings I should be getting at each location. What are the odds that I just have a couple of bad coils?
My question is how should I test the ignition system? Should I work my way from the stator and trigger down to the plugs or the reverse of that? I have the manual but it doesn't really deal with troublshooting the ignition. I feel that I can do it but I need to know what tools I'll need for the elctrical tests and what readings I should be getting at each location. What are the odds that I just have a couple of bad coils?