Yamaha F225 bogging. Need some help...

[thecowpen]

2003 Yamaha F225 TXRC - 300 hours
I only run non-ethanol gas. Previous owner ran some ethanol, but that was over 3 years ago.

Symptoms:

The problem began as an occasional brief "cut-out" of power at load, but seemed to straighten itself out and run fine for the rest of the day. The next trip, the engine would only throttle up to about 3000 RPM and then bog beyond that. Sometimes, I could "nurse" it past 3000 and it would run 4000-4500 RPM's intermittently. Sometimes, if I just left the throttle a little farther open past the bogging speed, it would "kick in" and surge up to the proper speed for a second and then bog back down by itself.

What I've done:
Since I've had a similar issue before and solved it by changing all the filters I assumed this would solve it again so I replaced them (Racor, main engine, F-filter, and VST screen). None of the filters were dirty. No evidence of water or stale gas. Took the boat out to test and it made no difference (maybe even a little worse).

So then I assumed since I had never had the injectors cleaned, that had to be it. Pulled them, sent them off for cleaning and new screens. Installed, and now it's running even worse. Could not even get on plane when I took it out last weekend.

The motor starts and idles fine. Primer bulb is not sucked flat. Priming the bulb has no effect on the bogging at load. The motor will rev to any speed in neutral without load. Can now only get about 2000 RPM at load.

So now I'm not sure what to try. Hate throwing good money after bad just blindly hunting for a solution. I haven't put a pressure gauge on the fuel rail yet, but I see Harbor Freight has them for $20. Would the engine behave this way if the high speed pump was bad? Will the motor even run without the high speed pump turning?

Thanks for any suggestions.

[thecowpen]

I put a pressure gauge on the fuel rail and have about 42 psi, so I think I'm good there.

I discovered that the low pressure pump isn't running when I turn on the key. It turns fine when I connect 12V directly to the pump. I'm reading no voltage at the connector with the key on. I was expecting voltage for 10 seconds and then off for 10 seconds.

Any advice on what to check next?

[99yam40]

I am not positive so wait for someone that knows for sure, but I think the 12+ should be there at key on and the negative is what ECU turns it on and off with.
If you do not have the + then you need to see where it is dropping at

[fairdeal]

that lift pump "isn't supposed" to be running at key on (except for the first five-ten seconds)
only after the engine is running
and then yes, under 1200 rpms: 10 sec on, 20 off
(although according to some manuals, continuously for the first three minutes after starting)

[justincblades]

I had the same exact symptoms. Ended up being two bad injectors. Now fighting a new problem.

[justincblades]

Pull injectors and send them off to be tested and cleaned. I had replaced almost everything.

[thecowpen]

Thanks for the replies. I feel like I'm getting closer to chasing this down...

... I think the 12+ should be there at key on and the negative is what ECU turns it on and off with.

I've got no voltage at the pump connector with key on whether grounding to the connector or the block.

that lift pump "isn't supposed" to be running at key on only after the engine is running and then yes, under 1200 rpms: 10 sec on, 20 off

OK, this is a little confusing. I found reference to a section of the service manual for checking the low and high pressure fuel pumps. The manual indicates that both pumps should run at key ON, without the engine running (see image from service manual). I guess I could just put the muffs on and crank it, but I'm not sure I could hear / feel the pump with the motor running and the intake cover off...

[fairdeal]

"should run at key ON, without the engine running"

yes, but only for 10 seconds, low pressure pump, 5 seconds, high.

You've checked your rail pressure; can't have that without a working high pressure pump....

or for that matter, a working lift pump.
Also you said " Priming the bulb has no effect on the bogging at load" which would seem to indicate that the lift pump is working....

the lift pumps only job is to keep the vast full
the high pressure pumps only job is to maintain fuel rail pressure
clearly they are both "working"

what is it that's happening at >2000 roms, only under load?

[justincblades]

I chased my tail for two months on why mine was doing the same exact thing. Did everything you are doing. Went to two mechanics. Finally one pulled injectors, had them tested, and two were bad. Runs fine now.....now I have another problem I am chasing.

[TownsendsFJR1300]

I chased my tail for two months on why mine was doing the same exact thing. Did everything you are doing. Went to two mechanics. Finally one pulled injectors, had them tested, and two were bad. Runs fine now.....now I have another problem I am chasing.

You may want to start a new thread for the new issue. It gets confusing having the two together. Thanks..

[justincblades]

Already did that. Just trying to save the guy some time and money. Had two yamaha mechanics say it wasn't the injectors til one decided to pull them just to make sure. Two were bad. He'll they were about to have me buy a new ECM (or whatever yamaha calls the computer.)

[thecowpen]

Already did that. Just trying to save the guy some time and money.

I do appreciate that, but I've already pulled the injectors and sent them off for cleaning and new screens. If anything, it was a little worse after doing this.

the lift pumps only job is to keep the vast full
the high pressure pumps only job is to maintain fuel rail pressure
clearly they are both "working"

what is it that's happening at >2000 roms, only under load?

It bogs down. I can "feather" the throttle up only so far. It runs OK up to that point, but if I try to give it any more, RPM's drop and the tone of the engine sounds kind of "throaty" if that makes any sense. It sure feels like a fuel volume delivery issue to me.

Is it possible for the high speed pump to "pull" sufficient fuel to keep the engine idling without the low speed pump? The lack of voltage on the low speed pump seems significant.

[fairdeal]

"Is it possible for the high speed pump to "pull" sufficient fuel to keep the engine idling without the low speed pump?"

I can't say for certain, but I doubt it,

"The lack of voltage on the low speed pump seems significant."

Perhaps - but each time you turn the key, that pump will only be powered for a few seconds - are you sure that's not happening?

[thecowpen]

Perhaps - but each time you turn the key, that pump will only be powered for a few seconds - are you sure that's not happening?

Definitely does not run at key on - not even a little bit.

[fairdeal]

ok now that its morning I remember - the pump is always getting 12V, its the ground that that switched by the ECM. so if you've got nothing at the plug, thats a problem.

It would be interesting if this has anything to do with that mysterious "fuel pump driver" - have long wondered what goes on in there.....