OX66 Problem

[dunepray]

Good Morning Keith,
Thanks for the response. Yes, I have a Yamaha service manual. I have been working through the electrical systems on the motor and in the end have not discovered the problem. All electrical systems have checked out. I haven't as yet, but I will remove/clean/replace all the electrical connections. I haven't heard of Deoxit. I have used 626 in the past on electrical cleaning.

Last night I pulled all the fuel injectors. I agree fuel injectors need to be cleaned professionally, when they definitely need cleaning, but I thought a general look around was warranted. Turns out I don't think the injectors are the issue. I pulled the little filters at the back of the injectors and they all looked new. Cleaned them anyway with carb & choke cleaner. Using my homemade cleaning harness I pushed carb & choke cleaner through all injectors. All appeared clean. I removed the fuel rail and sprayed some cleaner through. All looked clean. After work tonight I will take the VST and HPF regulator apart again and re-clean. I had done this previously, but I am going to work backwards through the fuel system all the way to the tank. Once I get this done, I will bring two 3 gallon tanks with me on the next shake-down cruise. One I'm going to prepare with Seafoam decarb mix. The other I'll load with regular Rec-90. I'll decarb first, then run the small regular Rec-90 tank to see if performance has returned. Then return to main tank and test again to see if the problem is still there.

I'm crossing my fingers,
Dune

[dunepray]

Just checking in while at work. I've been thinking about the fuel starving issue and recall that there is air in the motor mounted fuel filter viewing cup. I'm thinking that air should not be there. AM I RIGHT, FOR ONCE!!! I removed the check-valve just past the fuel filter and it's working fine and is clean. My feeble mind tells me the problem lies at the filter or somewhere between it and the tank.

Just Thinking,
Dune

[jb123]

Hook up an aux tank ball hose to filter
Do a vac test

[bajakeith]

Ox 66

have you checked fuel pressure on the VST scrader valve ?? I would also recomednd running on a spare (portable) tank..and not made by Tempo or moeller...west marine crap...that will tell you if the tank and fuel system is a issue...also try to install the primer bulb near the motor with the arrow pointing up towards the sky !! next to wrong batts (deep clycle) I see primer bulbs in the wrong angle...if she now runs good on a spare tank, ck the anti sipon valve in the barb on the tank..."nasty little booger".. I will not tell you to remove it,,,BUT,, I sure the hell DO !! and I will run clear sectin with a vacuum guage "T" in and look for high vacuum ( 2.5 HG MAX ) or air bubbles in the clear tube will running the boat,,main tank..."GET ER DONE !!''......

[bajakeith]

Service manuel

If it doesn't say YAMAHA and instead is printed by seloc or Haynes or any other brand besides YAMAHA ,, it's to be used for fire starter !! trust me on this...LOL

[99yam40]

Just checking in while at work. I've been thinking about the fuel starving issue and recall that there is air in the motor mounted fuel filter viewing cup. I'm thinking that air should not be there. AM I RIGHT, FOR ONCE!!! I removed the check-valve just past the fuel filter and it's working fine and is clean. My feeble mind tells me the problem lies at the filter or somewhere between it and the tank.

Just Thinking,
Dune

there have been many people asking about the filter not being filled all the way up and the answers have always been the same. No it will not stay full while running

[dunepray]

UPDATE:
Well, I think I found it. I looked at every connection in the fuel line, and all LOOKED good. I have done this on several occasions, and not seen any leaks. Last night, I took each connection apart, starting at the motor mounted fuel filter and working back. And, like the old adage of always finding what you're looking for at the very end, the last stainless steel ring connector going into the "out" side of the water seperator was broken. It didn't look broken, but it came apart when I put my hand to it. Not leaking fuel, but obviously air. The fuel line was original, so I went up to West Marine and got 10' of fuel line (can you believe $3/ft?) and replaced the line. All new stainless connectors and thought I was in business. The fuel ball was hard as a rock. Motor started right up. AND THEN DIED. What the hell!!! Anyway, I eventually pulled the line apart again and found that while pushing the couplings into the fuel line the inner lining of the fuel line detaches from the plastic and makes a nice ball in the fuel line so that the fuel can't go through. Did I mention that I'm a cripple? Well, all this crawling around in the bilge just about killed me, so I gave up for the night and will attack it again tonight. I'm pretty confident that this is the fix needed.

Dune

[jb123]

And a pressure test from the start would have helped find this

[dunepray]

Hi JB,
I didn't have a pressure tester in the first instance that worked. Leaked on me, but did give me 35 psi at the shrader valve while running. I threw that one away and a few days later when I got my good pressure tester I ran the boat, with the pressure tester, from idle to WOT. At NO time did it lose pressure below 35psi. Even when it bogged down and I couldn't get the RPM's up. I believed the engine was using more fuel than it could replace fast enough at higher RPM's OR I thought things were plugged up at the fuel injectors. Last night before changing the fuel line I watched the fuel filter bowl real carefully and finally saw small bubbles. The fuel line was original to the boat and degraded somewhat so I changed out the line with that crap line from West Marine (Made in Canada). I've always liked stuff made in Canada, but this stuff was crap. I took all the fuel line off the boat tonight, went back to West Marine (crabbed at them for the crap they sold me) and bought a different type used for below deck (Made in USA) and got it all back together. Engine started right up, No bubbles in the fuel filter. Seemed to run fine. I will get her on the water tomorrow afternoon. Hope this does it. One of the lessons learned here was to watch that filter bowl very carefully or you will miss the bubbles like I did.

Dune

[99yam40]

Sounds strange because I would think if it was sucking air and running out of fuel at higher RPM then the rail fuel pressure would drop

[dunepray]

Hello 99yam40,
Yes it does sound strange, but I had my brother and I on the boat watching the meters and fuel pressure the whole time. All I can say is that there was enough fuel coming through at that time to keep the motor running at lower RPM's. The engine just wouldn't go past 3500 RPM at one point. What I can say is that the first time I took the boat out with my neighbor she shut right down from WOT, and I didn't have a pressure tester at that time on the engine, so it probably did lose pressure. Only makes sense now knowing what was going on. I should have her on the water later this afternoon and hope I've cured the problem.

Stay Tuned,
Dune

[rodbolt17]

do what you wish but DO NOT get hung up on the filter cup running at half full.
its totally normal and its just how the physics of fluid dynamics work.
its funny that I look at posts that go for days,sometimes weeks, on issues that I see daily and can typically isolate in the first hour of diagnostics.

[dunepray]

Hello Again Rodbolt,
Not until I got the proper equipment could I make anything close to your claim of isolating the problem that quickly. Good Lesson to amateurs like me. GET GOOD TEST EQUIPMENT. A couple hundred bucks will go a long way in solving issues quickly. That, and the fact that I'm disabled and not really able to do these things very fast lends itself to slowing the progress down a lot. The one thing I can do is type, so if anything good came from all these posts, it's that others like me may learn something from my mistakes. Along with guys like you (who have expertise in these matters), guys that aren't rich (like me) can tackle most small jobs. For that I am exceptionally grateful to you and others who try to help.

Dune

[bajakeith]

fuel systems

I'll be short !! Today,, fuel systems are the biggest boat issue's I deal with on a daily issue !! I work on boats in the calif. area with eth...AGGG!! it does stuff that you would not belive..ever heard of "phase separation"...fuel line going to hell on the inside and looks good on the out side....Buy oem or serria only...nothing that says TEMPO or MOELLER !!! Go an argue with That !!

[rodbolt17]

E fuels.
US govt marine technician stimulous program.

we are the only nation that wastes our food in an engine.

E fuels cost us twice what regular gasoline does.