Yamaha HPDI crazy troubleshooting story

foreign I just said trying to make a video about uh thinking way outside the box when troubleshooting uh engine issues this is probably the craziest thing I've ever run into and I'm 50 now I started wrenching when I was 16 or 17 I went to school for automotive worked out for quite a few years worked on motorcycles a little bit on boats not extensively but uh then I went over and switched over to Aviation got my license there I worked as a mechanic for over 10 years on jet aircraft done a lot of troubleshooting on a lot of different stuff um this boat is a 2005 Stratus 200 Pro XL I bought for my cousin about a year ago at this time and it's got the Yamaha 225 hpdi on and uh the whole boat right now only has about 400 hours total from being a 2005 so it's the original engine or at least the original ECU my cousin bought it when it was I think he bought it in about 08 or so so it had a couple three years on it but it was never run a whole lot and uh he used a little bit over the years I think in 20 11 or so he burned a piston in the engine which was pretty common on these and uh so he took it back to the place where he bought it the service center and and they didn't rebuild them on site so they just ordered a remanufactured engine for it put all his engine accessories and ECU and all that stuff on it so they ordered this reman and put on there and he picked it up and when he got it back I remember him telling me that uh you know it never ran as good as the original engine did the original engine was was much more responsive more power would run like low 70s well then after they did this engine change he could only get like 65 out of it pretty slow coming up on plane just not the same thing that it was before so he had called him you know back back when this all took place and they kind of gave him a little bit of a run around and said well these engines had such a habit of you know burning a piston that um they're detuned now when they put them on so they make them last longer well through my research and stuff I found that wasn't true they haven't detuned them they have done some changes with pistons and just procedures on keeping fuel injectors clean and stuff like that and a few things running free in the fuel things of that nature but uh they're pretty particular on fuel clean fuel keeping injectors cleaned things of that nature but anyway back to the story so I bought it about a year ago and I was running at some and it seemed a little weird it ran pretty decent actually for power um it was a little doggy coming up on plane I could only get maybe 65 out of it on a nice smooth day without if I held it for a while I could get about 65 trimmed out so I joined some of the Yamaha and Stratus Forums on Facebook and everybody that had you know anything with a 225 in this model a boat was like oh I get 72 I get 73 75 whatever and I'm like man something can't be right and I did a compression check on it compression was even on all the cylinders I think 110 or 15 I don't remember now but uh even across all of them um when I got it it had like 350 or 60 hours on it when I plugged in the uh Yamaha software um anyway so me just being you know wanting things to run right and being particular about it I also noticed especially when it was cold it didn't want to hardly keep idling it idled real slow just barely chugging along until you kind of got it warmed up and which seemed odd to me and I I've got the service manual and I checked all the settings you know on the throttle position sensor and idle settings and all that stuff and so it seemed kind of weird but uh after a few runs I was mainly fishing focused on fishing and stuff I hadn't spent a lot of time that first last summer messing with it but I noticed uh come back and put a fresh set of plugs in it and the number six cylinder was always wet fouled and so I'd run it for a trip or two come back and all the plugs are about the same except number six was just oil fouled every single time and they're like well that cylinder obviously can't be firing and I tried a new set of plugs I figured well I got a bad spark plug and I'll start out with the simple stuff I put a plug in it and uh purposely checked it after the next trip out and it would be wet fouled right away and so once I got a little bit more time to start digging into it I started checking I thought well the coil is probably bad and it's not getting good fire to that cylinder so I swapped the two bottom coil packs around knowing that number five was good so I switched five and six around and the same thing no change still didn't do it so I thought okay well I got compression I got spark so it's got to be fuel so my fuel injectors got to be stuck open just fog and fuel in there and it's just fouling that plug right away so I was like oh that's all there is left that's got to be it so I was going to have the injectors cleaned anyway just so I had a good Baseline to start with so I sent the injectors out had them cleaned and tested told them to really watch close with number six letting them know kind of what the situation was so they called me a couple days after they got him and said yeah we tested them they're a little bit dirty but not not too bad uh nothing leaking no issues all the injectors work perfect and so I was like man what the heck you know that doesn't make any sense so they sent them back to me when I put the injectors in I swapped number five and number six injectors just for my own confidence I guess to troubleshoot further took it out I ran it some more still no change that I've gone through I kind of was putting a new plug in almost every time just to you know just to make sure I had a good plug in there and each time and still no different so I kind of started doing a little troubleshooting a little bit of research online and some people were saying well if you're if you're fuel pump the diaphragm fuel pumps on the side of the motor start leaking the bottom one it'll draw fuel right into that port and it'll flood that cylinder so I'm like oh that's got to be it so bought a couple new diaphragm Yamaha diaphragm pumps put on there still didn't fix it still getting fouled and by now I'm kind of running out of ideas you know and uh so I'd gotten in there kind of borescoped around inside the cylinder a little bit just looking at different things and uh didn't see any issues wrong with it check the compression to help them more times everything was still good and still had good compression so I start digging kind of deeper into it as the weather got colder I couldn't fish as much and and so I had actually hooked up a system a guy from work was helping me on it a little bit too because he's pretty sharp on this stuff and uh the one thing I'll say is a two-stroke engine does a really good job of masking a dead cylinder because since they're firing every every cylinder every stroke it's firing when you have a dead cylinder it's it's covered up pretty good you don't get the shaking and the stuttering like you do with the four cycle so but I knew that cylinder couldn't be firing because it was always wet fouled so I actually hooked up a deal where I got an annoyed light from the guy at work and hooked it into the fuel injector so I could see it flash when it was firing I put a compression gauge on it so I could watch that and I put a spark tester on there and I turned a video camera on cranked it over and then that way I could put it in slow motion on my phone and compared it to other cylinders and everything was firing and the fuel injection the spark the compression everything was hitting at the correct time and I'm like how the hell can you have compression Fuel and Spark but no no boom no no energy and I figured that's got to be what's causing the you know what's causing the the motor to not perform like it should you know like everybody else talks about how they perform so and like it did when he first got the boat so I'm kind of running out of ideas as a bar I'd take the engine off and uh you know send it out to have it checked out I was going to send it down to hydrotech and let them put it on a Dyno or they could run it at full full speed full RPM and really sit there and dig into it and figure out what's going on because I was totally baffled never read anything like this before and all the years are working on different stuff and uh so finally I pulled off the well I'd opened up the throttle bodies and I thought well maybe there's a blockage either on the exhaust passage or the intake passage somewhere maybe there's a rag that was stuffed in there years ago when they built the engine and it's just never had air coming through it but you know maybe there's enough getting through there to make compression but I didn't know so opened up the uh rolled the Piston down to where I had that the exhaust Port open and you could blow air in there and you could hear the air coming out just fine out of the bottom of the of the uh prop shaft housing and so then I thought well I'll check the inside of it so I sprayed the like starting fluid in through the spark through the throttle body with it held open shot some ether in there and I had a bore scope in this spark plug hole and you could see a little bit of a Mist coming in there so I'm like well that's open that can't be it so finally it you know basically at my width's end I decided to pull the Reed block throttle valve throttle bodies off the front of it and take a look back in there on the bottom side of the crankshaft with a borescope and so as I was looking around in there kind of comparing the number six to the number uh two or number four the one above it and then if I finally saw it and I was like holy crap I cannot believe this is actually what the deal is and so what it turned out to be to make a short story long is it actually had the wrong piston installed in it when the company did the remanufacturer on the motor they actually put a starboard piston you can see it has an S on it there on the bottom they put a starboard piston on the port side of the engine so this would have been fine in one three or five and number six it doesn't work so the issue is these Port cutouts don't line upright these cutouts don't line up quite right and luckily I never had a catastrophic engine failure because the ring gaps actually aren't in the right place when this Piston's on the wrong side because the ring Gap goes across the port and somehow it never snagged the port and tore the engine cylinder up which I have no idea how that how it didn't but with the borescope I could see like the stains in the cylinder the cutout wasn't matching up and then I go to the cylinder above it and number four everything was perfect you know the holes were all matched up fine and I was like oh I finally figured it out you know like after all this time so I was able to pull the head off and uh since I already had the the Reed cage out of the front of it you can see the connecting rods from that end and I was able to um unbolt the rod push the Piston out it barely cleared the uh I didn't have to take the engine off of the uh off the assembly but it just barely cleared to come out of there the engine didn't have that many hours on it but it's been running since like 2009 or 10 with this wrong piston in it so although my cousin didn't put a lot of hours on it it uh they've been run all those years with the wrong piston in it so I ordered a piston ring kit for it and a pin and everything and then uh hone the cylinder up real good uh cleaned it really well made sure I didn't get any grit in the passageways made sure everything was nice and spotless inside protected at all as I was honing it so I didn't get anything uh anywhere it wasn't supposed to be flushed it out good put it all back together and lo and behold it's firing like it's supposed to it runs good it's a whole different animal now I've had it down the Lake of the Ozarks but like 130 miles on it down there been out with it you know I don't even know a couple dozen trips I've probably put I don't know 40 or 50 hours on it for sure 30. I haven't looked at the ECU lately but um anyway so just kind of was pretty surprising I posted some information about that on one of the uh Yamaha Facebook groups and because I had been talking to people on there uh about the issues I was having so I think people were pretty surprised at what the outcome was on it and um it's kind of just one of those crazy things you know you don't think that uh when something isn't running right you know you're always thinking about just a fuel problem or a ignition problem or something that's you know the typical scenario you don't think something as obvious as or as strange as somebody putting the engine together with the wrong Parts you know like a piston and I should have saw it earlier the Piston had a ton of crud and stuff on the top and with someone I was borescoping in there I really didn't wasn't paying much attention you really couldn't see the uh the markings all that well on it and you know I was kind of blind to that because I was expecting it to be something totally different not a not the wrong piston you know of all things so uh anyway that was a huge thing uh fixed it and it's been running great haven't had any issues with just changing the one piston I run good fuel I've changed all the fuel filters I've you know I keep it uh I keep it running good I don't use ethanol fuel in it and uh I run stable 360 in it just to kind of keep the fuel in good shape even though I do use it quite a bit but anyway just uh just kind of a fun story there uh kind of weird definitely a head scratcher one of the toughest things I've ever troubles shot in all the years I've been messing with this kind of stuff and uh just thought I'd share that story so if anybody's I've got an issue with something that they're troubleshooting and they just can't figure it out you know sometimes you're not only going to think outside the box but you gotta like just open your mind up to the possibilities of anything because like I said this is just the craziest deal I've ever seen and uh anyway happy with the boat runs good fun to fun to fish out of and really enjoying it now so uh plan to keep the injectors cleaned every every couple years if not sooner and uh make sure they stay in good shape and uh I learned a lot if nothing else you know between the the manual and having the software to plug in and all the stuff I've been through I've learned a ton about the engine I'm not afraid to do pretty much anything to it including complete disassembly if I have to pretty easy to work on not really anything to be afraid of just you know if you get into something just gather all the information you can and make sure you for sure make sure you have a service manual at the absolute minimum and uh the yds software is really good to have as well I was able to run it in the driveway on a garden hose and look at all the parameters make sure I didn't have something obvious there with fuel pressure or ignition or something else going on so that was real nice but anyway uh just thought I'd share that crazy story and uh hope everybody has a good day see ya

Channel: E&M Outdoors

Views: 6,279

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Id: FLKM3LKBTG0

Length: 16min 41sec (1001 seconds)

Published: Sun May 28 2023