Input needed

[k3fishing]

Hi all, had the boat out this past Sunday and motor started (best way for me to describe it) acting like a car that has bad gas in it. It’s a 300 hpdi it was happening in all throttle ranges but not idle, at least not that you could tell. It would run good then bog then clear up then bog, bog, then clear up. I have seen it before but not like this. When it happened before it worked through it quickly, it made you say wonder what that was. This time it was doing it more frequently. It’s due for its annual filter(s) change. I did change the fuel water separator a month ago. Input?

[jdwo2212]

Change all filters and plugs and check fuel system would be where id start. Compression test also.

[CJ1]

fuel system,fuel system and fuel system. LP pumps to start. With it bogging you will be destroying hard parts very quickly. CJ

[k3fishing]

UPDATE... had motor serviced all filters, plugs, water pump, lower unit oil, seals. The motor sounds great and other issues are gone, my issue now is that the water pressure is out of wack, prior to service pressure would hop upto right around 20psi then at wot trimmed out it would drop down to between 10-15. But most of the time 15-20. After service it comes up to 15 and at 4600-4800 58-60 mph it drops down to just under 10psi not trimmed totally out, trimmed out wot it drops to almost 0. Not sure what’s up with that. It also is down 3 mile a hour and is taking longer than normal to get on plane. Any ideas? I’m calling the place that serviced it on Tuesday to let them know what’s up.

[CJ1]

Did you raise the engine? Add anything to the pad? CJ

[k3fishing]

Sorry, I guess I should have said it has a hydraulic jack plate and it didn’t matter where you put it it didn’t change the psi and/or speed

[k3fishing]

Update... service center didn’t find anything, said they blew out hose that runs to gauge. And didn’t see anything that would cause the speed loss. Is there a temp gauge that can be added to a hpdi?

[k3fishing]

Took it out today and it runs the same, water pressure still not right. And did a once over on the motor to see if any plug wires were loose and to see if there was any water leaking up top, and looked down at the prop and saw 27 T1, as far as I know and as long as I can remember it has had a 25 T1. I don’t want to accuse anyone of swapping it out, but I think that rpm and speed lose would make sensei it would only turn 5200 rpm and it’s usually around 5600, any thoughts?

[k3fishing]

Update... took to another mechanic he found that they used this yellow glue on all o rings/gasket on the water pump. He cleaned all that glue out and used grease, I took it out and ran it and the water pressure is back to 20+ through mid to high rpm. I tried it with prop that somehow showed up on my boat. It would only turn 5400 rpm I put the new to me T1 25 on it and it is back to 56-5700 and back to normal speed. Which confirms my fears that they swapped props with me when the boat was in getting serviced.

[WHITESTROKE]

Sounds like you need to visit original dealer. If he doesn't make things right let us know the name.