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04b 200hp OX66 problem your thoughts

skeetersx200

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"2004 model. Started a few wee

"2004 model. Started a few weeks ago. Motor always starts up fine and idles fine until a few weeks ago. Stalled in the morning, was hard starting, finally got started again and reved engine and warmed up, fished all day... no more problem. Last weekend, did the same thing in the morning. Started up fine and idled, while warming up engine stalled and was hard to get started. After many attempts finally got it running again feathering the hot foot. Fished half the day with no problems. On the run back down river was up on plane at about 5000 rpms when boat came off plane and engine shut off. No alarms, was hard to restart and acted like starving for fuel. Kept trying to start and felt like fuel filter clogged. Ran motor up to about 3500-4000 making run back towards ramp and would run fine for a mile or two and do the same thing. Each time I tried restarting, felt like it was not getting fuel. Finshed that day and came home. Replaced my fuel water seperator this week figuring for sure that was the problem however today, same issue. When first in the water engine started fine, idles good for about 5 minutes and shuts off. Crank it again and it acts as if it is not getting fuel, a few times it would start up and idle on its own fine, and would then die after a few seconds. Never got it up and running this morning. Would not stay running, put it on the trailer and just got home and broke out my book to start reading.
Getting ready to go outside and pull the plugs and take a peek at them but I am leaning towards a fuel problem like fuel pump diaphragms however some of the diaphragm symptoms I have read do not seem to effect the boat at idle.

Any help appreciated folks. Never had any mechanical issues whatsoever with this motor. Also when I changed the fuel filter, I poured a good sample of gas into a clear jar and fuel looks real good. No water, no cloudiness.

Whats the thoughts from the Yammie gurus?"
 
"Chip, sounds like maybe a car

"Chip, sounds like maybe a carb problem - either a clogged jet (starving) or even the opposite, a sticking float causing a flooding condition.

However, I would start back with the basics - ensure you have spark when it dies on you. It could very well be an intermittent ignition problem - at least rule out an ignition issue before you look any further..."
 
"This is an OX66 fuel injected

"This is an OX66 fuel injected model Graham. I am pretty confident it is fuel related. Have been reading similiar symptoms and am leaning to low pressure fuel pumps, but my symptoms aren't exactly as others have described with their pump problems. I am also wondering about the O2 sensor and or the TPS."
 
"Chip, sorry, wasn't even

"Chip, sorry, wasn't even thinking injected when I read your post.

If the TPS fails, usually the motor will not run at all, but if it is just starting to go and running erratic, could well cause a number of issues that may appear to be "something else".

All my troubleshooting notes on this however, require that it be hooked up to a computer to be checked...."
 
"Sounds like fuel pump to me.

"Sounds like fuel pump to me.

You can buy new replacement fuel pumps for about $32 each.

If you have clearish (white) diaphrams, they are defective from factory. The newer ones have black diaphrams. Just get new ones, for the price it is better than trying to rebuild."
 
"Thanks guys, it's going t

"Thanks guys, it's going to the dealer tomorrow. Hopefully my extended warranty will cover diagnosos and maybe some of the repairs. Will post the results to maybe help someone else down the road."
 
"Try an auxillary fuel tank,if

"Try an auxillary fuel tank,if you haven't changed the three fuel pumps in three years ,change them,
check filter inside vst. If your main tank has a check valve (one way flow) it may have trash in it. Sits on top of tank.Pick-up tube inside of main tank may have a leaf that comes and goes.Even your fuel injectors have a small filter on each. I believe your motor should be running at 35psi on the scharder valve ,check while problem shows up."
 
Thanks Bernard but went ahead

Thanks Bernard but went ahead and dropped it off at the dealer. Everything you suggested checking sounds like the right direction to head in fixing my problem. Dropped my boat off yesterday but said they probably wouldn't be able to get to untill next week. I will post the cause/cure hopefully soon.
 
"Dealer called yesterday said

"Dealer called yesterday said they had my Yamaha fixed. It appears that the undercowl fuel water filter seperator bowl (clear fuel filter under engine cowling) was cracked. He said it was leaking fuel, but checking out on the water and in the driveway I never saw a leak anywhere. Anyhow, it was cracked, dripping fuel, and the fuel pumps appeared to be sucking air and not getting proper fuel to the injectors. Said I must have bumped it with the engine cowling at some time to crack it. That's a possibility, as I had the cowling off a month or two prior to my problem starting. Haven't picked it up yet from dealer but he sounded pretty confident that was the problem and is now fixed."
 
"Thanks on the report, as you

"Thanks on the report, as you probably wouldn't see gas leaking on such a small dripping. The engine was no doubt sucking air through the crack and not drawing fuel from the tank. A good test for that kind of a problem would be to plug main gas tank line at the tank and disconnect at beginning of fuel pumps and do a hand vacuum pump test. Not a pro mechanic here, just good business to learn your engine."
 
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