150 hpdi fuel pump voltage drop

[aquaholicnc]

My 255cc has a pair of hpdi 150's. Fuel pump spins up fine @12v when the key is turned on. When starting, the pump voltage drops to 7.4, and the engine gets no fuel. I'm thinking O2 sensor? Thoughts?

[gnrphil]

I'm not sure the O2 sensor would have any effect on that, is your battery in good order.

[gnrphil]

I'm fairly sure that is normal, the pump spins up to boost pressure then slows down. This is only for fuel that is in the vst, the fuel draw from the tank is taken care of by the mechanical pumps. I have the specs at home on a diagnostic report so I'll get them later. I assume you do have fuel in the VST Tank.

[aquaholicnc]

So, here's the deal. Its at a Yamaha Service tech now.
I bought the boat after sitting for three years. Made one heck of a deal on it, but it had to run before I would take delivery. The place that had it had "Mechanics" on staff. Its a boat storage/dry slip/wet slip place that maintains customers boats. The boat owner paid for all new low and high pressure pumps, filters, batteries and injector cleaning. After a few weeks, the Marina owner admitted that they were not Yamaha service techs, and they were so busy with customers boats that it needed to go somewhere else. They put in the pumps, filters, batteries etc.... and one engine runs great. The other cranks but shuts off within a second, never really running. The original mechanic said that the voltage on the low pressure pump was dropping after the initial pressure up (Which to me sounds normal as the VST fills....) The boat owner knocked off $2000 more and said take it to a YST (That's where it is now)

So, I'm leaning towards Injector control module, but the shop is so backed up, they cant touch it until after the 4th.

[codman]

I have a 250 hpdi on my 25'. This engine has blown up twice, once on the original owner, under warranty, and then after 150 hours on me. My mechanic sent it to a place in Florida to have it rebuilt, they did a great job. There are filters all over that engine, some not documented. The second failure was due to the high pressure fuel pump running at too low a pressure. There are 4 undocumented bench filters in the high pressure pump assembly and one on each injector. All engine filters are 10 micron. You need to put a 2 micron high capacity fuel filter between the tank and the engine if you want to keep these filters from clogging. Just something I learned. You also need to buy the software to monitor these engines. It is available on ebay, since Yamaha is not making it anymore. You need this just to see what is going on with the engine, www.ebay.com/itm/Yamaha-Outboard-Jet-Boat-WaveRunner-YDS-Diagnostic-cable-set-Plug-play-/330918278833, I hope this helps.

[aquaholicnc]

So the VST was missing a few parts, and the medium pressure pump was bad. One more week.... I also had him pull both high pressure pumps and send them to be cleaned.

So cleaned injectors, new low pressure pumps, new medium pressure pumps and teated/cleaned HP pumps.