OX66 keeping shutting down, now what?

[Jdogsbass]

Hey guys, I've about lost my mind trying to figure this out was hoping you guys might know what to do from here. I have 2005 OX66 200. Awhile ago, my motor just would die randomly, wait a while and it would start back up and run fine. Well, this continued to get more frequent and after I had to trolling motor back to a weigh in I decided to start going after it. It acts like it just runs out of gas. This is what I've done and the results that I've seen:

Replaced all the gas lines all the way to motor (thought it was the last remaining line I hadn't replaced out of general care; no problems). Checked for clogs in the vent and main lines as well, no problems. Replaced the water separator too. The bulb was replaced a few years ago and gets hard when you pump it. This did nothing to help.

Went through the VST and changed the filter and the regulator screen. All of this was surprising easy and in good shape. This did nothing to help.

Replaced the O2 sensor with the NGK equivalent and replaced the o-ring and gaskets. This did nothing to help.

Went through the LP pumps although none appeared to be leaking when I loosened them up and squeezed the bulb. I did notice what appeared to be oil from the cylinder behind one and the gasket was missing, either never got put in a couple years ago or lost it during removal. Either way, I got new gaskets for them and swapped them with ones that were working just fine when I replaced them out of general care a couple years ago. Still this didn't help.

Thought my battery was a bit bad and wasn't seeing the voltage I'd like to have seen. So, I replaced this as well, went bigger anyhow and it was on it's 5th season. This did nothing to help.

Checked my compression, they were all with 5lbs between the highest and lowest and were at 90lbs (with a cheap set, so I'm not worried about the actual number; just that they were reasonable high and consistent in all cylinders). Shew, it's not blown!

Checked my fuel pressure at the schrader valve, hits 38 at initial power up and settles at 35. Tested it running in the yard, consistent 35. If I bleed the fuel while running, it bounces immediately back to 35.

It'll idle and come up to about 1700 all day without failing. When I cram on it, it jumps up as it always has, but after a few seconds/maybe a minute at most, it dies again. I have to turn the key on and off a couple times and then it will start up and idle again. It acts like the low pressure pumps can't keep up with the higher RPMs and dries the VST out. But, I've changed everyone of them one at a time and tested afterward and have gotten no farther.

This thing has performed flawlessly for the last 5 seasons I've owned it, and never sits more than a week when the ice isn't covering the lakes.

I have no idea where to go from here. Was thinking it might be my fuel relay or possibly even the electric fuel pump, but don't want to whip the bigger $ at another set of unknown problems. We have horrible Yamaha mechanics in my area and honestly don't trust that they find anything different than I have. Looking for what you gurus or someone that has had the same issue has to say about it.

Please help, much appreciated everone!

[Tonyc]

A few questions, does it always do it? Do you ever get up on plane, berunning along and it just dies? Does it ever not start and you let it sit awhile and then it starts up?

[Jdogsbass]

Yes, it does it all the time now, before it would happen every six outings, that I'd ever cut out and it always fired up and ready for action. It always restarts, just depends on how long it has sat or how many times it gets turned on and off now, it seems.

[Jdogsbass]

If you chose you chose to punch it, it'll go and fall off after a 10 seconds

[JoeFriday]

If you replaced the O2 sensor and didn't pull the plate and clean the tube, replacing it didn't have much effect. The tube can get clogged with carbon. When it dies, can you hear the fuel pump run when you turn the key on? If not, fuel pump relay could be going out. O2 sensor is likely not the problem though. Fuel pump relay problems are intermittent. If you crank it after it dies and it doesn't start, then will randomly restart later, look at the relay.

[dwmgg17]

I have a 2003 Yamaha VMAX 250 TLRB. Been going thru the same thing.it would just cut off while running on plane like cutting off a light switch. As soon as it set down i would hit the start button and it would fire right up and go like nothing ever happened. Did it about 6-7 trips in a row. Then it got to where it would not crank after it shut down. Sometimes it would after 15, 30, 45 minutes or maybe a hour or so. I have been eliminating items on the list as you are doing. I am looking at the lift pump or the fuel relay(65l-81950-01-00 on diagram #3 for electrical). Relay is $215. Feel for you and mine has worried the he-- out of me. Good luck.

[Tonyc]

The fuel relay is on the driver side of the outboard. Worked on a buddies ox66 200 last year, took the cowling off and tapped the relay with the rubber end of a screwdriver when turning the switch on, heard the relay click. Imho I think you have a bad relay. We tested his in the yard and it worked fine every time. Something with bouncing around on the water that would make the relay act up. It got worse and worse as time went by. One time it took us over an hour for it to fire back up before we learned the screwdriver trick.

[Amistad Tackle]

Yes. More than likely it is the fuel pump relay. Replace.

[JoeFriday]

I have a 2003 Yamaha VMAX 250 TLRB. Been going thru the same thing.it would just cut off while running on plane like cutting off a light switch. As soon as it set down i would hit the start button and it would fire right up and go like nothing ever happened. Did it about 6-7 trips in a row. Then it got to where it would not crank after it shut down. Sometimes it would after 15, 30, 45 minutes or maybe a hour or so. I have been eliminating items on the list as you are doing. I am looking at the lift pump or the fuel relay(65l-81950-01-00 on diagram #3 for electrical). Relay is $215. Feel for you and mine has worried the he-- out of me. Good luck.

Fuel pump relay. Could be other things, but that is the most likely culprit. The cutting off while on plane is a symptom.

[Jdogsbass]

Thank guys, that's kinda where I'm at right now too. I'll replace this next week and report back.

[Jdogsbass]

Yes, when I pulled the o2 I took the tube out too. It was really carboned up. Either way,
i cleaned both really well and got
nowhere farther.

[Jdogsbass]

Any way to test without just buying it, I have another day before spending too much time at work!!?

[JoeFriday]

Any way to test without just buying it, I have another day before spending too much time at work!!?

When it dies, turn it off, then turn it on and listen for the fuel pump running. No fuel pump running = the relay is going in and out.

[1bluemcm]

Thank guys, that's kinda where I'm at right now too. I'll replace this next week and report back.

FWIW, it does kind of sound like the fuel pump relay could be the issues, not based on personal experience but from what I've read around here over the years from others that have had an issue with it. If you do end up replacing the fuel pump relay and it turns out to be the culprit (I hope you get it figured out, I'd be aggravated at this point as well), I'll pay the shipping for you to send me the old relay. Been trying to get my hands on one so I can open it up and see if there are any other viable alternatives that we could use. PM me if you get to that point, if you don't mind.

[Jdogsbass]

Will do. Hoping to not have more spare parts, lol! I think an electric conversion kit for the low pressure fuel pumps would be a big hit as well. I know I would have bought one already. The OX66 is such a dependable engine, it's a shame it can be so finicky when it comes to fuel.

[Rich Z]

FWIW, it does kind of sound like the fuel pump relay could be the issues, not based on personal experience but from what I've read around here over the years from others that have had an issue with it. If you do end up replacing the fuel pump relay and it turns out to be the culprit (I hope you get it figured out, I'd be aggravated at this point as well), I'll pay the shipping for you to send me the old relay. Been trying to get my hands on one so I can open it up and see if there are any other viable alternatives that we could use. PM me if you get to that point, if you don't mind.

A 30a head lamp relay will work only if you know or can figure out how to correctly wire that thing. It's the same rely I used for the electric lift pump conversion.

[1bluemcm]

Yep, that's why I'd like to open one up to determine the pin outs/connections, then test it, and we'd have another option. I suspect we might be able to figure out the wiring from a good wiring diagram too, might not need to open up an original relay, I just haven't had time to look into that further.

[Jdogsbass]

It appears that the relay was the culprit. I installed it last night and tested without any issues for almost two hours; where before, I hadn't been able to go two minutes without problems. The first sign of this happening was two seasons ago and I dismissed it for being low gas tanks or preferring one tank over the other. It would happen a couple times the whole season. So, for any of you getting really random shutdowns, you might be heading for the same situation.

Thanks to everyone on this post and otherwise for guiding me through this adventure!

[1bluemcm]

Glad it worked out, that has to be a relief. Offer still stand, I'll pay you to send me that old relay. If interested, let me know.