engine trouble?

[JLAfarms]

Hi, I have a 1991 20.5 foot monterey runobout with a 305 and after 3 or 4 hours out on the lake it fouls the back plugs 1 on each side of the motor. When i pull them and look at them they have carbon on them they are not at all wet and I dont think they are oil fouled because they are totaly dry. I have recently had water in the tank and I have pumped tank dry and added gas tank cleaner at a heavy rate but I think that would have no affect on fouling the same two plugs time after time? Thanks in advance for your help.<br /> Thanks <br />Jerry

 

[Hog Wild]

Re: engine trouble?

Guess I would perhaps start with a simple suggestion of doing an entire ignition tune up. Change the distributor, rotor, wires, esp. the wires for those back plugs. Next you either have a intake/exhaust (fuel) issue in those cylinders or are getting like oil in them. Does it use any oil? When did this start happening and what was changed just before it started happening. Perhaps what is the compression test show on this engine?

 

[Skipster1]

Re: engine trouble?

If you don't wanna do the whole nine yards, you might want to make the changes step by step.<br />I'd change the spark plug harness first, using Marine spark plug wires (sounds like the rear cylinders aren't getting enough spark andthe rear spark plug wires could easily have broken down).<br />If that doesn't do it, then change all spark plugs, making sure you have the recommended plugs.<br />And then, if it still is acting up, change distributor rotor, etc.

 

[cc lancer]

Re: engine trouble?

Start with the inside of the distributor cap, be sure everything is shiny and bright.[like Christmas] <br /><br />Then look for cracks inside and outside, then see if the plugs wires for these 2 cylinders are burned, or damaged. <br />If you find nothing then put some money in new parts.

 

[JLAfarms]

Re: engine trouble?

the problem started I think when I got water in the tank at a local pump on the lake. After finding my boat was running poorly or didnt have the power to plane out I have checked every thing from cylinder pressure to rotor and cap which all checked out and seem to be fine I am using ngk ur4 plugs and I have pulled and cleaned the carb twice the first time it had water in the carb.I have also replaced the wires with 8mm accels (auto wires) and I have not been to the lake scince i replaced the wires