2004 Yamaha FX HO - Eats Motors!

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I recently purchased a pair of 2004 Yamaha FX HO's. One in good running condition and one with a blown engine. Previous owner claimed that he ran it through some seaweed, it overheated and blew. After purchasing, I realized the blown engine was from SBT as it had the FO# sticker on it. No big deal, i ordered another from SBT, installed it and sent the old one back. I took it out on friday, ran it for about an hour (never over 5000 rpm/20 mph) with no issue other than it seemed a little "noisier" than the one in the good ski and the engine shook a little more. I still felt comfortable enough to let my wife take it out saturday morning. She too was very easy on it but about 10 min in, she said it started cutting out and died. I circled back to her, checked it out (nothing obvious) and fired it back up. Ran ok for a couple more minutes then she said the warning light came on so she shut it down. At this point I'm concerned so I tow her and get it docked to check it out better. Exhaust was hot but not overly hot. Fired it back up and the cooling looked ok, water from the rooster tail and port side although the water was very hot at times. However, the oil reservoir was EXTREMELY hot. And I could not get the oil cap unscrewed for at least 15min until it had time to cool down. Oil was full and very clean. Sure enough, it blew on the return trip to the dock.

I'm assuming I have an oil pump problem. Considering it has already blew three engines (that I know of), I'm pretty sure the motors are not the problem. Should the oil pump rebuild kit from SBT solve my problem? Any help/suggestions are greatly appreciated!!!

[Technical Support]

Re: 2004 Yamaha FX HO - Eats Motors!

The FX H.O. is very temperamental with oil pressure and oil cooling, I have rebuilt pumps on them in the past and still had issues producing correct oil pressure, your best bet is to replace the complete oil pump assembly; there are check valves and other components in the pumps assembly that can cause issues besides just the pump rotors and impeller. Other known issues with that engine may include leaking fuel injectors or stuck open fuel injectors caused by bad drivers in the ecu (computer) that may cause fuel to mix into the oil causing the oil to become fuel saturated and not lubricate properly. These engines seem to run great when new but don’t seem to age very well. The Vx 110 and the regular Fx 140 seem to have a much better life span.

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Re: 2004 Yamaha FX HO - Eats Motors!

Thank you for the prompt response! Not the best of news but thanks for all the info. I'll be pulling the motor this weekend and I've already ordered a new oil pump. I'll let you know how it works out.

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Re: 2004 Yamaha FX HO - Eats Motors!

So I pulled the motor yesterday. Pretty catastrophic. The connecting rod basically sliced through both sides of the block. It even blew the oil filter off! I attached some photos.

The crankcase had oil in it. It was a dark grey/green mixture. Same in the bottom of the ski that I attached a picture of. Hard to tell if the top end was getting oil or not and I did not want to tear it down per SBT policy. I drained the remaining oil from the block into a bucket that happened to have a styrofoam cup in it. 10 minutes later it had eaten a hole in the bottom of the cup. Does this mean there is gas in the oil? Possibly due to the ECU issue you described above? Is it possible the oil and fuel did not mix until the engine blew? Hoping to avoid the cost of a new ECU...

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Re: 2004 Yamaha FX HO - Eats Motors!

Hi, unfortunately after nearly 3 years I am back :( You guys replaced the engine above under warranty (thanks!) and I reinstalled with a completely new oil pump assembly. Everything seemed fine (although I have proably only put about 10hrs on the new motor) until last weeked. It blew again in nearly the same manner. There is now a small hole in the side of the block just above the oil filter (not quit as big/bad as last time). Any further suggestions?