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Three of my cylinders are fouling. The left side of the motor gets fouled within an hour of use. Possibly overfueling or not enough air. The other side is fine. They flused injectors and even replaced a coil but I went to use it with new plugs and right away they turned black and were wet. Any suggestions??
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THEY meaning mechanic/shop ? and THEY have no explanation ?
how does it run otherwise?
you might check your primary fuel pumps, if one diaphram is bad, the crankcase will draw gas right in, you would also see unspent fuel out the prop. -
or possibly a torn oil pump o-ring ? anyone else shed light on this ??Comment
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I had the boat in at the Yamaha shop. The mechanic thought it might be a injector problem.They also replaced a coil. $700 later it is the same as it was. I removed the fuel pumps one at a time and checked for leaks with the engine running and couldn't find any. how would I check the oil pump to see if it is leaking? This engine was using a fair bit more oil then the other one. I don't think this engine was rebuilt, it did have a new brain box a while ago. Is the oil pump leaking into the crankcase consistant with the cylinders on the port side being fouled and the starboard ones not?Comment
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it runs alright with fresh plugs, still not as much power out of the hole as my other motor. I run at 36-3800rpm and it will run for about an hour before it starts losing considerable power.Comment
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I checked both the diaphrams on the fuel pumps. when I removed them there was a bit of oil on the engine side (normal I'm sure). I started and ran the engine for about 1 minute and didn't detect any fuel leaking. I'm wondering about the possibility of the oil being mixed too rich on those 3 cylinders. Can that happen? How do I go about finding out if the oil pump is leaking into the crank case? Do you think I should get another oil pump to try?Comment
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I would seriously look for a dirty o2 sensor or clogged transfer tube behind the sensor. Plugs will foul within minutes if the tube is clogged (motor goes full rich).
Odd that it is only one side. Not sure what that implies.
FYI- I experienced a failed oil pump and all it did was smoke like crazy when starting.
edit: and use alot of oil (18-1)Comment
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I just installed 2 new fuel pumps and replaced the fouled plugs with new ones. Went for a quick ride. Still doesn't have the punch the other motor has. I will replace O2 sensor next.Comment
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have it tested first...unless you can afford to sling 300 bucks....and clean if dirty.
http://www.boatsetup.com/O2sensor.pdf
the symtom of a bad sensor is varying rpms up hi, and not hitting the max rpms(or equal my other, at least in my case.)Comment
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still got the problem after pulling the O2 sensor and cleaning it. There was a little carbon but the sensor was looking good. The port side is the side that is fouling, not the side the O2 gets the reading from. My mechanic thinks it is an injector problem. Any other thoughts?Comment
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