Went fishing offshore 50 miles the other day and both engines ran perfect. Before leaving the dock, we changed the fuel-water separators. Set up to troll and switched to reserve tank to burn that up since gas was 4 weeks old. Trolled all day and when we went to run home, port engine’s RPM’s kept going up and down (from 10 to 30 back down to 10) and we could not get on a plane. Switched to main tank and replaced the spark plugs (which were almost a year old) and engine seemed to run fine. HOWEVER, every now and then (like when hitting a wave hard), RPM’s would drop (quickly) and then continue working fine. At the dock, we changed the engine fuel filter and emptied out the water separators. Seemed to run fine so took boat for a cruise last evening. Ran perfect….even up to 35-40 RPMs (34 knots) so cruised out the inlet (which was a little rough). Hit a wave and problem started again …..RPM’s would drop down to 10 and then back up again but very infrequently. Does anyone have an idea what might be going on? I’m thinking something is loose on engine or one of the 3 fuel pumps is starting to go. Had this happen on the starboard engine when boat was new (Summer 2000). Doesn’t sound like bad fuel since we switched back to main tank and starboard engine was never a problem. I did notice the primer ball for that engine didn’t seem to be pumping – although once I started engine, fuel seemed to flow fine. Could this cause the symptoms? Also, when checking the new sparkplugs at the dock, 1-2 of them already had a small build up of carbon. I do use the RING FREE and STAR TRON religiously.
Help diagnosing RMP problem ('00 Yam F225/Saltwater Series)
- Thread starter grady33
- Start date
To add to my post, I'm now wondering if this is the 02 sensor? Haven't had them cleaned in awhile. Is this a do it yourself job?
Notwithstanding the members' experience on this site, Andy over at thehulltruth.com on the vendor forums for the Shipyard Island Marine is a good place for this one.
Thanks. I posted it to the hull-truth. At this point (based on what I'm reading)..... I'm thinking it's got to be a fuel pump, 02 sensor or the VST Tank Filter problem. Have not cleaned the 02 sensor in 2 years. Anyhow, I really appreciate the response. Thanks, David
David my vote is for a bad low pressure fuel pump. Had a very similar problem years ago with my 2000 250 EFI outboard. Replaced the blown fuel pump and problem went away. Very easy job and not too expensive. I think the cost was about $40 each (three per motor).
One question, your post reads "00 Yamaha F225/Saltwater Series" - is it a four stroke or a two stroke? I though the four stroke was intoduced later than 2000 but I may be wrong.
One question, your post reads "00 Yamaha F225/Saltwater Series" - is it a four stroke or a two stroke? I though the four stroke was intoduced later than 2000 but I may be wrong.
Scott,
Thanks for the reply. YES - they are actually 2 stoke (225) OX66 engines. I just spoke to my mechanic and he suggested I check the 02 Sensor (very carefully). He said I could easily replace them on the other engine to see if I had a bad sensor.
Regarding the fuel pump, I was actually thinking the same thing you were .... to go ahead and replace them - which I think I'll do this weekend. Have you ever messed with the VST (vapor Separator Tank Filter)? Saw some threads from folks with similar RMP problems who went ahead and replaced them. The engines have ran great (8 years) without any problems. Guess it's time to start replacing a few things here and there - especially since I go out 40-60 miles each weekend. Again, thanks for the reply.
David
Thanks for the reply. YES - they are actually 2 stoke (225) OX66 engines. I just spoke to my mechanic and he suggested I check the 02 Sensor (very carefully). He said I could easily replace them on the other engine to see if I had a bad sensor.
Regarding the fuel pump, I was actually thinking the same thing you were .... to go ahead and replace them - which I think I'll do this weekend. Have you ever messed with the VST (vapor Separator Tank Filter)? Saw some threads from folks with similar RMP problems who went ahead and replaced them. The engines have ran great (8 years) without any problems. Guess it's time to start replacing a few things here and there - especially since I go out 40-60 miles each weekend. Again, thanks for the reply.
David
If they're the original fuel pumps, they're probably on their way out but I can't see the pumps causing a problem when they get rocked. Normally the engine just falls on it's face when you give it gas. Did you ever chage the other fuel filters (there's quite a few of them)? You may also want to pull the VST tank off and check it out.
Thanks. I have to agree and will go ahead and replace them. YES - changed the engine filter and separators but did not mess with the VST. Is it possible to replace those without taking tank (unit) off engine? Is this a time consuming or simple? Boat is on a lift.
Yes you can simply pull the top off the VST if you remove the eight or so phillips head screws. I think you will need a new gasket though. I forget if you clean a screen filter in the VST or replace it, been a while. No need to pull the whole unit if you do not want to.
O2 sensors can also be cleaned. However you may also need to replace the gasket on them well (be very delicate and you should be fine). Make sure you clean the carbon from the tube inside as well while your at it.
O2 sensors can also be cleaned. However you may also need to replace the gasket on them well (be very delicate and you should be fine). Make sure you clean the carbon from the tube inside as well while your at it.
Sounds like a bad fuel pump, likely the low pressure pump, we had the exact problem happen on my HPDI. Try pumping the ball by hand when it does it, if it seems like it runs better, or wants to run harder then before, then that is for sure the problem.
Since the problem occurs when you hit a wave, I suspect that something is loose ( electrical) or that something gets shook up and is blocking fuel. Since only one engine is acting up, it's not a tank problem. It still could be a check valve problem in the bulb. Does the bulb appear to be colapsing? I agree that pumping the bulb when the problem occurs is a good diagnostic test. You should feel the fuel in it and if it is a pump problem, the engine should rev up when you pump. I'm giving 3:2 odds that its not fuel per se.
Thanks. I'm going to replace the bulb and then clean the 02 sensors (swap them between engines) and replace the fuel pumps today. Will let everyone know if that clears the problem. If not, I'll clean (or replace) the VST filter. Hopefully this will solve the issue plus a little preventative maintenance can't hurt. 
i have not seen a bad O2 yet, but u never now
i have seen more fuel pumps shot than clogged VST strainers
also u might want to replace the high pressure filter and the check valve before the fuel filter
let us know
i have seen more fuel pumps shot than clogged VST strainers
also u might want to replace the high pressure filter and the check valve before the fuel filter
let us know
Background: 2000 225 YAM Saltwater Series 2 stroke was having intermittent RPM issues at higher speeds.
After changing spark plugs and fuel filter on port engine, problem still occurred. I then went ahead and changed the VSP filter and replaced the 3 low pressure fuel filter (both jobs very easy and were done on a lift). Will take you about 1-2 hours each engines.
Tested boat and went offshore (50 miles) the following day. Engines worked like a champ!!! Both VST filters were dirty, but basin was clean - except for a very light white haze which I cleaned using RING FREE and lint free napkin. This was the first time the VST filters and fuel pumps were changed and engines are roughly 8 years old.
Did not mess around with the O2 sensor since boat was working fine after doing the above. Will tackle this job after season is over in a month or so.
Again, this is a very simple do-it-yourself job.
David
After changing spark plugs and fuel filter on port engine, problem still occurred. I then went ahead and changed the VSP filter and replaced the 3 low pressure fuel filter (both jobs very easy and were done on a lift). Will take you about 1-2 hours each engines.
Tested boat and went offshore (50 miles) the following day. Engines worked like a champ!!! Both VST filters were dirty, but basin was clean - except for a very light white haze which I cleaned using RING FREE and lint free napkin. This was the first time the VST filters and fuel pumps were changed and engines are roughly 8 years old.
Did not mess around with the O2 sensor since boat was working fine after doing the above. Will tackle this job after season is over in a month or so.
Again, this is a very simple do-it-yourself job.
David
Had a feeling that was the problem, glad to hear you are up and running again!! Any fish on that 50 mile run? Fishing off northern NJ has been slow in the canyons, most charter boats are running 100 miles south to go after bluefins instead of running the canyons. Many professional sportfish teams as well as charter captains on the E coast are deeming this one of the worst offshore seasons the whole E coast has seen in 20 years, hopefully things turn around fast.
Thanks and I hear ya! We ended up with a 35-40 lbs yellowfin. Tuna fishing is extremely slow off OC right now but I did hear the White Marlin bite was OK in the canyons (poormans). We fished all day at the Hot Dog (trolling most of day and switching to chunking the last two hours) and not a single bite followed except for 2 false albe’s. I may try some overnight canyon trips if the weather holds. Where are the 60-90 lbs yellowfins?