2006 yamaha f115

trying to help out my uncle with his 1890 warrior. been having troubles with the motor and have had it at the dealership three times and they are still stumped. motor runs fine at first. idles fine, gets up up on plane fine and does everything it needs to do. into the run it acts like it starts to miss and when you get to where you need to go is when it really acts up. Bogs down incredibly bed and will often stall out. if you start it up and try to go rpms wont reach even 2500. i am friends with one of the mechanics working on it and we tested it and seems like when it is acting up it is only running on injectors 1 and 4. started with replacing the coil for injectors 2 and 3 and did not fix it. all injectors and screens were checked and flushed and turned out ok. After the motor sits for a while it will take off perfectly fine again like there’s no problem. looking for some input. heard the vst filters are a common problem but why would it then affect only cylinders 2 and 3? seems electrical as if something is getting hot and making it act up then when it cools down will work again. Just looking for some ideas. anything is greatly appreciated.

Sounds to me like it’s starving for fuel. I would replace the hose going from the motor to the tank, it may be collapsing and starving the engine for fuel. Also check the vent on the fuel tank. If the vent is plugged it will not allow fuel to flow like it should. The cylinder 1&4 thing may just be a coincidence. Gotta check the simple things first. Good luck

i know its been a year but thought i would give an update. Problem still exists. The dealer working on it had a yamaha expert come up and do some digging. They suggested switching the pulser coil. Didnt fix it. Then they discovered that wiggling the wiring harness would sometimes make it act up. Switched out the wiring harness and didnt help. Next they suggested that the wiring harness shorted out and ruined the ecm. after a while of debating of throwing an ecm at it they finally did. Still didn’t fix it. Been a bad situation

Tom Anderson wrote:

Sounds to me like it’s starving for fuel. I would replace the hose going from the motor to the tank, it may be collapsing and starving the engine for fuel. Also check the vent on the fuel tank. If the vent is plugged it will not allow fuel to flow like it should. The cylinder 1&4 thing may just be a coincidence. Gotta check the simple things first. Good luck

My Mecury had same problem and i did replace the hose,pump,female connect…and works perfect.!

I have zero experience with yammies,but when two cylinders are affected at the same time,they have to have something in common,ie,ignition coils,or a sensor of some sort if used for them.

usually on four cylinder four cycle motors,one and four are at the same place at the same time,same with cylinders two and three,of course this is when a flat crankshaft is used,and they most likely use a double stacked coil firing two cylinders at once,its called a wasted spark system,when it works,its great,but when one side of the coil starts to break down,it affects both cylinders on that coil stack.

my thought is if I had it,I would be checking to see if the coils are losing spark when its hot and acting up,if that checked out good,look for a fuel problem.

please post what you find out as I am curious now.

Levi . wrote:

we tested it and seems like when it is acting up it is only running on injectors 1 and 4. started with replacing the coil for injectors 2 and 3 and did not fix it. all injectors and screens were checked and flushed and turned out ok. After the motor sits for a while it will take off perfectly fine again like there’s no problem. looking for some input. heard the vst filters are a common problem but why would it then affect only cylinders 2 and 3?

Just curious how you came to the conclusion of it “seems” when it’s acting up it’s only running on the 1 and 4 injector?

I’d really suspect with all the electronic parts and connections replaced there’s not much else it can be in the electrical system, other than possibly a weak ground but I’d highly doubt that. Or a kinked wire that looks good externally, but is weak on the inside, that’s a tough one to diagnose and chase down.

It almost sounds like it’s vapor locking intermittently somewhere in the fuel delivery system. Has anyone checked the primer bulb when it’s acting up? Has the fuel system been ruled out with hoses, vents, etc?

Could be running fine because it’s getting enough fuel at higher rpms then starves itself? Then it relieves the pressure after it sits for a while?

Have a John Deere that had an incredibly small air leak in the fuel shutoff value that was intermittent. Acted like electrical issues. Checked the fuel system and it “seemed” like it was working properly. Threw some electrical parts at it, cleaned all connections and battery cables, cleaned the carb and was about ready to call it quits. Had great spark, compression and everything seemed to be working properly. Put an inline glass filter in it and there was a tiny amount of air getting in the system that was causing the issue. Got rid of the shutoff and bingo runs like a top ever since.

What about the ignition switch or the tether shutoff? Have seen some tether shutoff’s and ignition switches do some weird stuff.

I’m a pretty firm believer after seeing grounds do some bizarre stuff on vehicles, tractors, outboards, diesel’s, etc that if it’s something really bizarre, I’ll clean and retighten the grounds even if they look good just for the kicks and giggles. Lots of times it’s not it, but sometimes just loosening and retightening them has solved some head scratchers that are otherwise unexplainable.

If the shop and mechanics tell you it couldn’t be this or that after all that digging, I’d start with what they say it isn’t.

Keep us informed and post up what the problem is when it’s found. My curiosity has been peaked.

Good luck with it.

We took it out for a test run and ran it for probably 6 miles until we got it to act up. If i remember right there is a coil for cylinders 2 and 3 and a coil for 1 and 4. When it was acting bogged down we unhooked the coil for cylinders 2 and 3 and there was no change in the way the motor ran. Hooked that coil back up and unhooked the 1 and 4 cylinder coil and the motor went completely dead. The boat has recently went to another shop. Maybe a fresh eye to the situation will catch something.

I had a the high speed fuel pump go out on an 07 F60. It intermittently acted up like your describing. I was told by the mechanics that it’s a common problem if you’ve ever ran the boat out of gas. I had a faulty gas gauge and had ran it out of gas twice.

I’m no mechanic but I figured I’d throw this experience out there.