Is this normal? I just recently changed VST filter, fuel filter, plugs and mystery filters to see if that would fix it. It does not throw any codes so I was curious if this is a safety issue with these motors. I bought the boat a couple months ago. It mainly does it right after launching or if I idle an area too long, say if I'm trying to graph an area. It seems like only a couple of cylinders are firing, then the rest of the cylinders kick in after a few seconds after I throttle down. I have a hot foot too, and was considering this as an issue, maybe the throttle cable is sticking. I know on some motors that only 2 cylinders work on idle with the remaining kicking in after a certain rpm is reached. Any help would be greatly appreciated.

sorry for your problem. i had so many fuel related problems with my 200 hpdi that it was less expensive to sell it and get a new motor. much easier on my mind. i got to where i had absolutely no confidence in the hpdi. i hope you get it figured out.

Thanks smooth move, but that is not good to here. I was hoping that this is normal activity for the HPDI. It runs great after on plane, but the starting is the problem, and only when it is a cold engine or running on idle for awhile. I know these engines are finicky and you need to run ring free and ethanol free to have the best performance. It just seems it may be something easy. When I took off the old plugs they did not have that much carbon build up.

You also need to check the medium pressure fuel filter, fuel water separator and the low pressure fuel pumps.

Did some reading on the low pressure fuel pumps....That's next on the list to change! I think I did replace the fuel water separator (filter?). Where is that located? Medium pressure fuel filter will be the last to go...since it is a more expensive item. It does smoke some at start too, so I am thinking the low pressure fuel pumps. Thanks Bahala.

Rather than wasting money throwing parts at it, try taking it to a good mechanic. Would have already cost you less and it would be fixed right. What you are describing is probably either low pressure fuel pumps, neutral safety switch or a burnt out tuner. They are great motors if taken care of properly. I've been running one for 15 years now.

Chris B from what I've read the low pressure fuel pump is a maintenance issue. Since I did not get a service list of what the previous owners had done, I'm going to be changing out those parts anyway to have a baseline. I can change the low pressure pumps no problem. Just needed to know where to start. And it's not at the point where I cannot drive the boat, just annoying at this point and I know it will eventually need attention. Thanks for the input, I'll check the other 2 as well.

Thing is if your starving the engine for fuel you will likely blow it soon. Don’t continue to run it or it will. A mechanic can hook up his laptop and tell you in a minute and tell if it is losing fuel or something else. It’s warning you so take it seriously. Don’t let it be a $8,000 mistake. Good luck.

I had a tech hook it up when I bought it and it did not show any codes, and that was a couple months ago. The previous owner did say he ran 93 octane, and I'm wondering if that has something to do with the bogging. I've changed to 87 ethanol free with Yamaha ring free hoping that will clear up the issue. Just made the change so I will have to run it. I agree, I do not want to make an $8000 mistake and that's why I'm changing everything I can out. I plan on getting the injectors cleaned by a tech over the winter.

All,

Just to give a quick update, I had a tear in the fuel line where it went into the low pressure fuel pump. I cut out the tear and put new low pressure fuel pumps with the correct zip ties, in the picture these are regular zip ties and will not put pressure all the way around the hose. Once I had the parts, it took me roughly 30 minutes to do.





Took it out last night and there was a huge difference. No smoke on startup and the boat jumped right out of the water and did not bog at all. Also, my rpms increased. Where I was struggling to get 4800 rpms at 55 mph @ WOT, I'm getting around 5200 rpms at GPS 58 mph at WOT. I'm using a 23 pitch prop and about 4" under pad. I can definitely get more out of this motor, but my jackplate is maxed out. Not sure if the last owner installed it where it could be raised to the height needed. I have a 25 pitch prop that I will try too and see if that increases the RPMs. Thanks for the input guys and just wanted to give you a quick update on progress.

Your proper work was preceded by some rather sloppy DIY! As you increase pitch on a prop, you can expect a drop in RPM. That 25 is likely to be too much prop for your rig. As for the jackplate, can you move the engine up on the mounting plate? .....Just like you would use different holes on the bracket of the outboard to raise a motor bolted direct to a transom? If sounds like it got mounted with the wrong set of holes in the motor's bracket.

I'll have to check to see which hole slot in the motor it is mounted to. Is there anything to consider if I were to move it to the bottom holes on the motor? What about the jackplate mounted to the boat? They are mounted in the middle hole, and there is 1 more hole that it can be moved up to.

What boat is this on? I have a VZ225 on a Champion 201 with a 25P 4 blade Mark Cruxton Razor 4XL Prop and it will turn 5700-5800 and about 64-65 MPH GPS with two people, 30 gallons of gas, and a fishing load. Prop is 3.5" below pad. If you are only turning 5200, either something is wrong with the motor, it's set up or you have way too much prop for the boat it is on. The HPDI motor drops two cylinders at idle and is running on 4, but they should come back on as soon as you begin to accelerate. This causes the motor to kinda vibrate and sound like it is missing at idle (Uhh-- that's cause it is missing).

The prop to pad distance will make a huge difference. You need to get that set up for what your boat likes, but I would start and 3.5" and move up and down 1/4" at a time and pay close attention to hole shot. Also, the vent holes on the prop make a huge difference. Best way is to plug them all, run the boat and see how it reacts, then pull them out one at a time until the props starts blowing out at launch and then put the last one back in. My prop has 8 vent holes, most only have 4. I have 6 plugged and two open.

Wayne

It's on a 2003 Nitro 901 CDX. I know I can get to 5700-5800 rpms and that speed if I could lift the motor. I believe my prop is about 4" below pad. Nothing is wrong with the motor and I know about the idle running on 4 cylinders. My next step is trying to get the motor moved up a hole or two on the mounted jackplate. I think that will make all the difference. I'm running a Yamaha 23-M and I don't believe they have holes, or at least that can be taken in and out. I'm also curious if my hot foot is not allowing the throttle to be wide open. I'll check on that too. Have you heard of this scenario before? Thanks for the info, and hopefully I'll get her dialed in.

I am surprised that with a 23 Pitch prop that you are not able to actually over-rev the motor, even with the prop at 4" from the pad. I would look at the hot foot cable. It may not be opening up. Until recently, I had a 27 Pitch V-Max prop and boat would run close to 70 MPH. I changed to the 25P 4 blade to get a better hole shot. My 27 pitch Yamaha Prop did not have pluggable vent holes either, it actually has 3 retangular slots.

Wayne