Been catching hell with my 2001 Yamaha HPDI. It has been one thing after another! Started at the beginning of the season with low rpm, found the high pressur pump was dirty. Sent it and the injectors off and had then cleaned by flagship marine. Put all new filters, pump, and injectors back on the engine and ran great! After 2 trips is started cutting in and out badly then all of the sudden would not idle. Hooked the computer back up to it and had a tps code. For the tps was bad and replaced. Ran great again (well on the hose). Put it in the water and still will not idle. Anything over 1000 rpm runs like brand new, but when you go back to a idle in the water it will die and sometimes if will not restart. I took it to fun in sun and they looked at everything and said they were not sure what it was but they wanted to send the injectors in. I know this in not a problem with the fuel system, but I do not know enough to about these engines to really go any farther. I am looking for someone who is a expert with hpdi motors. If you or someone you know is please contact me @ 817-715-7279

For forum help with HPDI there's a guy with the handle Rodbolt on iBoats.com that is the most knowledgeable guy I've ever come across. Lots of post and he is an HPDI expert

I would be checking all of the gaskets involved with the injector r&r. Sounds like a vacuum leak.

I would make sure high pressure filter clean and link and sync

Thank you, I will check with him!

Pulled the injectors out and checked and replaced the gaskits. Still there. Preformed a link and sync when I replaced the tps. Lol this thing has a ghost!

I could check it out for you Im on west side McKinney

May be an exhaust tuner burned out.

Good call Tommy

Ok, well I had a slow day at my shop and pulled the boat back in. I am not one to through any other dealership under the bus, but I was pretty upset with Fun and Sun in Hurst. I took the boat in there to have the tps sensor set and they spent over 5 hours on it and said they did not know what was wrong with it. (Original problem was the boat will not idel after replacing tps) They wanted to pull the high pressur pump and injectors and send them in, I just did that less than 2 hours of fun time and told them that was not the problem. They said the fuel pressur was low and that I had low compression on one bank. I went up there and paid for what they did and brought it back to my shop and started to look over everything they had done. My diagram fuel pumps (that they said they checked) were leaking because they did not tighten them back down to the block, second my tps harness was pinch form were they unbolted my vst to check the pumps, third I was missing a bolt that held my throttle body to the manifold, fourth my engine and gauges would not shut off (accessories would not work) even with the key out of the ignition. I fixed all the problems that they made and found they did not hook back up a ground that they disconnected from my battery that was keeping everything hot! After that I hooked my computer up to it and found the tps sensor code was still there. Reset the code and put it in a run tank to see if it still would not idle. It did not, so I looked at where they had set the tps and it was way out. I set the tps (to Yamahas spec) with engine running with my laptop hoked up and fixed the engine. Everything is working now.
I know you are asking your self why I did not just do this my self and if I am a marine shop why did I take it to fun and sun, well we do not work on hpdi in my shop. (Only reason I did on this one is because this is my personal boat) I thought by taking this to Fun and Sun I would be in good hands! I called lance back up and told him everything I found and that I fixed it by doing what I asked them to do in the first place and did not even get so much as a sorry.
I know there are some die hard Fun and Sun guys out there and the only reason for posting this is I have another cusotmer that bought a boat from them in the last 2 months that had some things go wrong in there service department as well. I thought it was a fluke because I have never heard anything bad about them, but apparently they are having some trouble right now.
I also want to add that my compression was 100 even and fuel pressure was 10psi higher than factory.( which if you ever send a pump in to flagship this is what they do) Hope this helps anyone with any issues they may have in the future with a Yamaha or Fun and Sun.

Sent you a pm