Yamaha 200 hpdi troubles

[flickershads]

Here is the full story below:

It started a couple weeks ago after my boat had been sitting for about 3 weeks (used it for 3 weekends in a row before this with no problems). I drove about 10 miles and fished a couple places with no problems and then I started it and it sputtered and shut off. It did this a couple times but once I got in gear it took off fine. I headed back to the ramp and as I was going I could hear it missing or actually cutting out as I was going. I took it out the next day and had the same issues. I figured it was bad gas so I put some gas additive in it and it worked fine for the next 2-3 hours. That brings me to this last weekend. I filled it up with premium gas (assuming it would help my bad gas problem) and then ran about 20 miles on the water with no troubles. Then it started in again and got progressively worse as the day went on. It would cut out hard enough when you were going to almost throw you into the steering wheel and would hardly idle or run at low rpm's. I called one boat place and they said it was probably a fuel filter. I talked to another one and they said either a fuel issue or spark plugs. I replaced the spark plugs and it did not help.

Also, I talked to the previous owner and he had some similar problems a few years ago and he got a pressure sensor replaced I guess. Another mechanic said it sounded something like that again but he did not know and referred me to somewhere to get it hooked up and see if it threw out any codes. That place said no codes would show up unless an alarm is going off which it isnt.

Has anyone ever had the pressure sensor replaced or does anyone know what the symptoms are like when this goes out? I think I will either start with replacing the pressure sensor or going through all the fuel filters and see what works.

I talked to a lot of different people and have posted on a few forums and I do not get the same answer from anyone. It is frustrating that it has to be so difficult. I hope to not throw a bunch of money at things and not know if it will help or not. Thanks for your help!

[rodbolt17]

its not difficult, its mostly simple.
a pressure sensor wont alarm,may set a code but a faulty sensor on the HP rail wont affect engine running.
actual low fuel pressure will do as you describe.
you must test the medium pressure rail AND the HP rail AT the failure RPM and load.
no amount of snake oils nor high octane gas will clean the VST filter,medium pressure filter nor HP pump filters.

you can blow a piston trying though.

[flickershads]

I replaced the fuel filter (looked to be in need of a change but no water apparent in canister). I also replaced fuel/water separator and drained contents into jar. No apparent water in there either but there is a little debris that looks kind of like rust in there. Does the debris in there mean it was probably plugged?

I have not had a chance to try it out yet just wondering about stuff in separator. I want to cover as much as I can myself before I take it out and try it and before I take it in and get charged.

[reel_adventure]

Listen to rodbolt17. He knows what he's talking about. Had a similar problem with my 300 HPDI. Had the VST and the MP & HPP filters replaced and the problem was resolved. The fuel filters and the fuel/water separator are not the culprits although changing them does no harm.

[Biminibrad]

Hpdi

Rod Bolt knows a lot more than me but I have had my fair share of problems and problem solving. Could be the shift interupptor switch is acting up. When in neutral motor only runs on partial cylinders. If it is getting hung up or intermittently kicking in, it will stumble flat on its face real fast. If not it, clean all your filters at same time. Including the fuel water sep, there are 5!

[99yam40]

come on now guys this is an old thread,
no need to drag it up