I give up! HELP PLEASE

[William W.]

This was my original post.....................I have a 2003 Yamaha VMax 200 OX66. My last three outings the engine has been acting up. It started as sptting and sputtering as I went to plane off as the boat was nose high about to jump up on plane, it sputtered but went on, did this all day. The second time, when trying to plane off, it would shut down, crank up and idle fine but I couldn't get it past that point this time, had to prime the bulb and take off quickly, it would still spit and sputter just before it got on plane. Yesterday, took it out and I really had to work to get it to plane off, priming the bulb no longer worked, I had to keep the RPM's below 3000 and let it just build up enough speed to plane off, once it did, it started acting like it was missing or something at WOT. I thought I may have a fuel delivery problem when all this began, but yeterday I took the cowl off and had my buddy drive the boat, I watched the fuel water seperater the whole time and had plenty of fuel running through it. Any thought on what could be my problem?


Since I posted this, I have tried all the suggetions, cleaned the VST filter, changed all three fuel pumps and changed spark plugs. So I took it out today with high hopes she was gonna run like new..................WRONG, it has still gotten worse, it would still start and idle fine, but now when you give it much more gas than a no wake speed, it shuts down. I did manage to get it to plane off once, but I had to have the engine trimmed all the way up and it still hesitated, and I could only get it on plane one time this way, all other attemps failed, even when it did get on plane, it was still missing really bad. One thing I didn't change was the gaskets for the fuel pumps, the ones that go between the engine and the fuel pump, could that be my problem?

Any other suggestions, or just take it to the dealer and fork out the big bucks?

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Modified by William W. at 3:32 AM 7/12/2010<br /><br />
Modified by William W. at 10:33 AM 7/12/2010


Modified by William W. at 2:42 PM 7/12/2010

[Kramr]

Either it's not getting a good spark or the fuel line/injectors are clogged. Your changing the pumps probably knocked more loose.

2 things to try before the dealer:

New plugs

Lots of fuel line cleaner

[William W.]

Changing the plugs was the first thing I did, along with the primer bulb. I have always kept a close eye on the fuel water seperater and that filter, never had to clean it out, there has never been any trash or debris in there of any kind, the VST filter was also clean when I checked it, so I am hoping that it is not trash at the injector, but just incase, I had trippled the recommended amount of injector cleaner and have ran it twice since then and it has steadily gotten worse.


Modified by William W. at 2:43 PM 7/12/2010

[Kramr]

Sounds like your covering all your bases. Still sounds like it's being fueled starved.

The one time my motor developed a miss was bad gas. Any chance this started after you added fuel?

[William W.]

I had not added gas when this all started, and I have been using the ethanol treatment since the first day I put ethanol gas in it. I was talking to someone at work today about it, and they said that sometimes the gaskets will not seal as they should when you remove a component from them and re-install without changing them out, so I ordered the 3 gaskets today.

[falcooon]

I am no expert but just brain storming....
How about the air side? Choke stuck closed? Electrical problem keeping the choke closed...
o2 sensor?
compression check?
Electrical spark system ...wires etc.

How about the exhaust ... obstruction??

Just thinking out loud here and I hope it gives you other things to check out.

Good luck and please remember to post the solution if you find it!

[William W.]

I haven't checked any of that yet, but when I do figure out what the problem is, or if the dealer figures it out, I will post it.

[toledo freak]

i would seriously check your fuel pump resistor!!!!!!!!!!! IM me if your not familiar with this

[okieblazer]

I have a 2003 225 ox66 with all these symptoms. Changed fuel pumps twice, removed and flow tested/cleaned the injectors, changed plugs twice, all new fuel lines, cleaned the tanks, changed o2 sensor and still is getting worse each time that I take it out. Has never run over 5400 rpm's since a new powerhead was installed last August. Been to the dealer twice, over 700.00 spent dont know what is wrong. I am pulling my hair out. IDEAS!!!!!!!

[falcooon]

The power head change certainly adds a variable ...
However, think "outside the box" Air, exhaust, electrical (spark), choke, linkage, etc, etc.

Don't get stuck on fuel issues only!

Good Luck to all and remember to post the solution once you find it!

[dhagemei]

Isolate boat fuel system with temp tank (OMC and MERC has max flow compared to others) and hook directly to fitting inside cowling. Problem goes away, then we know the boat fuel system is at fault. Basic process of elimination, before replacing parts from hearsay. Please give us these results.

[okieblazer]

First of all, I need to apologize to William W. for hijacking his post. I have already tried the outside fule tank and line, no help.

[William W.]

It's fine, "hijacking" my post, you never know, whatever my solution is could also help you, and vise-versa. I just wish I could get this damn thing figured out, it bugs the crap out of me if something isn't running right. And I have two weeks off coming up in August, I WANNA BE ABLE TO GO FISHIN' !!! Hopefully I, or if it comes to it, the marine shop, will have it figured out by then.

[hooken203]

These engines have no choke or choke linkage. You have really covered most stuff. You really need to try an outside fuel source. 6 gallon tank if you are able to get fuel without ethanol for this tank I would do so. And try to stay away from the stuff if you can.I know in some states thats all you can buy. Both of you guys need to check all your power and ground connections on the engine take the covers off the fuse and relay area and make sure all those nuts are tight and are making good connection. If you are using fuel injector cleaner something other than seafoam not a good idea and never over do it. That stuff eats plastic and will trash those new fuel pumps and can damage injectors when used in high doses. That goes for your cars and trucks also. You could have an exhaust tuner thats bad as in cracked or melted the lower unit needs to come off to check this and its not very likley but it does happen. Back to the fuel thing see if you can find an auto shop that can check the amount of ethanol in the fuel.Take them a sample of your fuel and have it checked. Never more than 10%. Let me know what you find out.

[okieblazer]

I have actually ran with a 12 gallon outside tank, no change. I strictly run real gas with ringfree. It seems to be getting worse each time I go out. Sunday it would not plane out, partner went to front of boat, finally broke over and ran at about 4800 RPM's, surging all the while.

[jbfarm]

Your boat is running just about like mine. If you take your air box off is it full of oil.

[hooken203]

Yours is the one that has had the power head replaced. For sure I would be checking those power and ground connections. Neither one of you guys talk about a compression check. Have you done one?

[William W.]

No, there is no oil in the air box.

[okieblazer]

Mine has the powerhead replaced last August. Yes compression test has been done twice, good numbers. No, there is not a lot of oil in the air box. Hydro_Tec checked the injectors, they were in specs. When the powerhead was replaced they replaced the tuner also, telling me that the old one was melted. I had the middle piston on the port side blow a chunk off on the old powerhead. I should add that it starts every time by just bumping the key. Took it out last weekend after replacing another fuel pump and still doing it. My partner had to go to the front of the boat twice just to get on pad, then would only run about 4800 rpm.


Modified by okieblazer at 7:26 AM 7/17/2010

[hooken203]

I dont want to beat a dead horse but did you pull all the pumps at this time and make sure there isnt more that one leaking. Heres another dumb question.The prop have you always ran this prop? Too high of pitch or vent hole plugs wrong. If you had a bad fuel pump could the O2 sensor be fouled again. You can hook a volt meter to it and see if it is switching or varying voltage as it should.