Yam 2004 F150 Power Loss

"Run the motor only about 10 h

"Run the motor only about 10 hr per year; has about 50 hrs on it. Has been gradually losing power over last 10 hrs or so of use, was very sublte at first, only down 2-3 mph and was hard to really say somethig was wrong. Started idling a little rough about same time. All seemed to start shortly after filling tank at marina. Over the winter drained the tank and re-filled. When taken out this year was still a little off, about 3-4 mph off normal WOT. Now has progressed faster over last few hrs of use and is down about 50% on power and seeminlgy going over a cliff. Idles sort of rough for the most part and sometimes stalls on accelerating from idle. At WOT it will sound OK and start to plane up sounding pretty smooth at first, then gradually starts falling off with the feel of a lost cyl or two, only hits 25 mph when would normally hit 42 mph. Checked the plugs - all the same and look almost new. Main filter OK. Removed VST and both the inlet filter to the VST and the high press pump inlet filter seem spotless. VST needle vlv looks new. Have ordered SW diag kit to read sensors but will not get here in time to get me and family back on the water before end of our vacation. Any ideas on things to check "in the blind"? Also, the fuel flow from the main tank seems totally fine, ie, squeeze bulb and flow into the motor when VST was out, seemed totally un-restricted. Any ideas that come to mind which could get me back on water would be greatly appreciated. Thanks!"

"Shock it with SeaFoam. Run a

"Shock it with SeaFoam. Run a 16oz can in one gallon of fuel on a small tank. Let it idle for 15 minutes then run it at full speed for 15 minutes. Repeat this cycle until you have run out the gallon mix. Reconnect the main tank and run it at full throttle for 30 minutes.

Shocking it with SeaFoam will do a few things, first it will remove any water in the system. Second it will remove any varnish and third it will de-carbon the cyclinders."

check for gas in oil

check for gas in oil

"180v....thanks for the advice

"180v....thanks for the advice. Was worth a try at something simple, and also to rule out an on-board fuel tank issue. Gave it a try today, but no joy. Idled pretty good at first after a couple minutes. But took it out on the water and still a dud. Ran for 5-10 min or so at WOT and it seemed to be winding down the whole time. Came back in and idle was real bad. Put it back on the main fuel tank, same result. Kept dieing, but got it back on trailer. Seems to have deteriorated into a pronounced lope/instability at idle, and a pronounced miss at higher throttles.

Checked the plugs, which looked good the other day. Today only #1 looks good, with #2 and #4 a little dark, and #3 really dark, but none wet.

JIT - the oil does not look or smell of any gas, and oil level has not risen as best I can tell. Can you please eleborate on what you are thinking here? I've seen several of your posts before where it seemed you were linking fuel pump issues causing gas in oil. Can you please help me with the connection on that?

Anyway, we're off the water for rest of vacation. When I get back home it will be time to pull out the fuel press and compression gauges and the diagnostic software...unless better ideas come up."

"We have a 1999 Yamaha 250hp o

"We have a 1999 Yamaha 250hp outboard,when ever we put it into gear or put a load to it it will stall out. Can anyone help with this.
Thanks
Jeff"

"i,m having the same issue wit

"i,m having the same issue with a 2006 f150, suspecting the fuel pressure regulator, as according to specs, fuel pressure should be 45psi, getting 36psi with reg connected to intake manifold, and 45psi dissconected, will keep you posted."

Reggie - are you having same i

Reggie - are you having same issue as the F150 or the 250 problems above?

I was also looking into fuel press for my F150 problem. Yam manual says 45 psi when key turned on but before engine start. Says 37.7 psi after engine start. So 36 psi you are seeing could be ok?

Thanks

"chuck, my f150 is very errati

"chuck, my f150 is very erratic at idle and almost stalls, and then comes back up again, but idles fine when hose from reg is disconected from intake manifold."

"Wanted to post a follow-up to

"Wanted to post a follow-up to let folks know what fixed the problem. I suspect this could be pretty common. Plugged in Yamaha diagnostic system. No error codes, all sensors looked fine, 66hr total on motor. Checked fuel press - 38 psig at idle. Compression check - 180 psi on all cyl with plugs out and throttle plates open. Pulled injectors, sent to WitchHunter.com. Got them back in 1 week, $82 total for 4 injectors. Report back was static flow of 120,137,99,105, and spray pattern of fair,good,poor,poor before cleaning. After cleaning, flow was 138 and good pattern on all 4. Took it out today for a test...idles perfect, back at 42 mph/5800 rpm, just like new, what a difference! Thanks for related posts that folks made that led me to injectors and Witchhunter - I was very impressed with their service."

"chuck , mine was the same pro

"chuck , mine was the same problem, cleaned injectors, motor is fine."

"I had the same problem, and t

"I had the same problem, and the same fix. Seems like their is an issue. Does anyone know if Yamaha acknoledges the problem or is it the Ethenol?"

run seafoam

run seafoam