150 HPDI Vmax has serious lack of power

[nazbom73]

So Just performed a truckload of maintenance and repair on my 2000 VZ150TLRY; new filters, de-carboned, new LP pumps, all from a sputtering issue at higher RPM's. Fuel was leaking through exhaust so pinpointed this issue at the LP pumps and replaced and all was fine...on the muffs. Went to lake last night and Whoa! Serious lack of power, the Boat struggled to get on plane, would power past 4400-4500 RPM depending on trim and generally sounded like it was missing on at least one cylinder. Was running fine till the fuel pump issue. I got frustrated last night and put the boat away. GOing to compression test the cylinders tonight but at a total loss as to what this could be.

I did change the basket filters in the HP pump so it's not them, the VST is clear, new O-ring as well, new Medium pressure canister filter also. I have the service manual for the motor so going to start diagnosing what I can but wondering if anyone has had this issue or might know what direction to head.

Thanks in advance - Mike

[nazbom73]

So had some time this afternoon. Got the Clymer and was able to download a copy of the Yamaha service manual. Went through some trouble shooting steps, compression test (all between 100-110 and within 10%), checked and reset the TPS was slightly low on voltage, Checked and cleaned the O2 Sensor, Check HP pump pressure, Checked Fuel injectors. Did a spark check and the #3 cylinder is lacking spark. Oh, also checked the neutral start switch, good. I ran the motor in and out of gear, checked all plugs. Started by pulling boots while it was running (in gear, prop removed) and engine changed pitch on all plugs except #3, so tested spark on all plugs and no spark on # 3. Getting too dark and threatening rain so packed it in for the evening to continue tomorrow. I'll read manuals and internet all night. Does anyone have any ideas or suggestions as to this issue? I plan on checking the boot resistance tomorrow (start hopefully right) and then up the line. Appreciate the help and taking time to read and consider.

-Mike