1987 yamaha 225 excel oil fouling plugs after extended low speed operation

[wwb1969]

good afternoon i have a 1987 yamaha 225 excel in a 225 boston whaler with approx 700 hours on motor.This year i am having a problem with the motor oil fouling plugs after slow speed operation of about 1 mile.I live on a creek with a no wake zone that leads into lake ontario after slow speed operation i start to oil foul the plugs and the motor seems to be using more oil than normal.I have not touched the adjustment on the pump at all.If medium to high speed boat runs perfect no problems right up to 5300 rpms can the oil pump wear out internally with age to produce more oil flow? any help would be greatly appreciated thanks.

 

[gsyfishy]

Re: 1987 yamaha 225 excel oil fouling plugs after extended low speed operation

Most older model motors with external oil pumps, will pump different amounts of oil for different operating circumstances. It may mix the fuel and oil at 50:1 at idle and low trolling speeds, as you throttle up it will change. You may need to have the oil sending unit checked, and adjusted accordingly.

 

[rodbolt]

Re: 1987 yamaha 225 excel oil fouling plugs after extended low speed operation

if all the plugs are fouling I would not suspect the oil pump. if you have the original pump it should have 6 nipples pointing up, if you have the newer version it will have 3 on each side almost horizontal.
the early style pump had internal check valves the newr had inline check valves.
you will also need to check the low speed charge coil and the recirc check valves located on each cyl. its the little steel 90* nipples with small gray hoses. there are 6 of them.
if they fail plug fouling at low speed is the result.
manual shows an oil output test, I use a consumption test as well. use a marked glass or plastic tube and multiply the oil output by 6 and see if the running consumption is correct.
also check the TPS voltage for correct output.

 

[wwb1969]

Re: 1987 yamaha 225 excel oil fouling plugs after extended low speed operation

hello rod bolt i hope you would respond.you helped me on this same boat with the fuel airating but is was actually boiling do to the vaccum on the system.the nipples are all up i have a factory manual and as far as i can see it does not give me any procedure on oil flow to the carbs.also not to be a dumb *** low speed coil reference to the oil pump.any help would be greatly appreciated thanks wayne