2001 150 Yamaha running irractically

[BTF112989]

I have a 2001 150hp Yamaha HPDI longshaft that has started to run irractically. I was off the coast of Florida on Thursday and when I was headed back in my engine would drop about 1000 or 2000 RPM's then surge back up to normal. At first I thought I hit something in the water or that my impeller intake was clogged but that was not it. I continued to run back toward the shore but then it started to happen more frequently. The engine even died completely 2 times while I was running at 2700 RPM's. I could hear it start to come and then it would surge 8 or 10 times every few seconds. I was immediatly thinking fuel system and I checked the fuel filter and it looked fine. I checked the water/fuel separator and it had no water in it so I was ok there. I pumped the bulb while going and it still did it so I don't think it's the fuel pump. What should I check next? I can usually work on my smaller engine but this one's fuel system looks a little too complex for me? Should I just take it in to the dealer? I'm thinking that it is a chunk of debris in the fuel lines somewhere. It could be anywhere and I don't really know how to find it. So I'll probably just take it in. But any ideas on what it could be?<br /><br /> Thanks<br /> Ben

 

[rodbolt]

Re: 2001 150 Yamaha running irractically

could be debris, a quick test with the fuel vacum gauge or running directly from a known good portable tank will tell, most likly a clogged VST filter or a clogged medium pressure filter. has the maint schedule for the 100,200 hr as well as the calander maint been performed by a competent tech or is it a run it till it breaks motor ?

 

[BTF112989]

Re: 2001 150 Yamaha running irractically

I'm guessing it is debris as well. The gasoline was fresh that morning. I was making about a 70 mile round trip and I did fine the first way but it started acting up on the way back. So I was running alot of gas through the motor that day. I only have 94 hours on the motor because I bought the motor a little over a year ago and it was sitting in it's original crate for 4 years when I bought it. It still has the warranty on it. I have not made it to the 100 or 200 hr service yet. I had it serviced at 20 hrs by the dealer and I was planning on having a 100 hour service done by the dealer but my week of boating was cut short by this. I would have made it to 100 hrs if I had run it another 2 days like I had planned. I take good care of my engine and do not run it till it breaks. I was also running Ring-free fuel additive in the boat's gas when this occured. I was using the constant treat amount but could this have caused the engine to act up? I know it's supposed to smoke and cough when you use the shock treatment but I don't know if it does it in the constant treatment application. I was running the ring-free in it for 3 days prior with no acting up.<br /><br />Where are those filters located on the engine because I would like to take a look at them and inspect them? What does VST stand for? I have seen many people call them this but have never known what it means.

 

[rodbolt]

Re: 2001 150 Yamaha running irractically

after sitting that long I am amazed it ran at all. usually the medium pressure pump locks up.<br /> the basic fuel system goes from the engine mounted filter to the 2 lift pumps to the metal can on the FWD port side. that can is the VST also known as vapor seperator. in that can is a needle valve and float assy that can gig ya, as well as an inline medium pressure,50 PSI, electric pump, from the medium pressure pump it goes through a 180 dollar inline filter that needs yearly replacement to the High pressure pump which contains sone non servicable filters so keep the trash out. from the high pressure pump fuel goes to the fuel rail at roughly 700 PSI and the excess from the high pressure pump is returned to the VST.<br /> your engine also has an O2 sensor that needs periodic cleaning and output testing, either buy the equipment and service literature or pray your tech has at least done the electrical and Fuel systems modules and understood them. if he has he will have the corresponding gold stickers on his diploma. you will find the O2 sensor is a 200 hour or annual check, my experience dictates 75-100 hours it needs to be cleaned and tested. most if the get dirty and fail can be cleaned but will fail again rapidly. key is to keep it clean. after cleaning there are 2 running voltage output tests that must be run in the water, no other way.<br /> both have tech bullitens out on the correct procedure.<br /> how good is your dealer ?

 

[BTF112989]

Re: 2001 150 Yamaha running irractically

My dealer is a gold star dealer or something. I can't exactly remember what the award that Yamaha gives out is but this place has it so I think that they are pretty good. <br /><br />ok, well I know what those are but I feel better taking it to someone that actually knows what they are doing. I can do pretty much anything to my old 10 hp engine but this one is alot more complex. Thanks for all of the tips and describing what the problem is to me.

 

[rodbolt]

Re: 2001 150 Yamaha running irractically

look for the school gold stickers on the diploma, 5 star is good but but not good enough for working with HPDI. if the tech is not sharp the tech can create more issues than they solve.<br /> and the O2 sensor CANNOT be checked, let me repeat, CANNOT be checked or tested on a flusher.<br /> you will find 90% of the issues with HPDI are fuel or rigging related, electrical failures are quite a rarity. if the shift cable is not adjusted as per the tech buletin that came out about 2002 the shift position switch can trigger and depending on RPM when it triggers can take out up to 4 cylinders. most times we use the lap top to quickly find what is not wrong rather than what is.