bypass hpdi system

[TRICKY1121]

can someone tell me how to disconnect or bypass the oil injection system on 2005 Yamaha vz 225.

[rodbolt17]

ya simply cannot.
why not just maintain a very good system ?

[boscoe99]

You can simply remove the oiling system components and then trick the engine into thinking that it has oil (so as to not set the alarm/RPM reduction mode) by making a simple electrical jumper connection. I can tell you how after you have removed the oil system.

Now when you add oil to the gasoline (premix) keep in mind that the premix is going to be injected directly into the combustion chamber since that is where the gasoline goes in the HPDI VZ models. Therefore, the bearings, crankshaft, pistons, rings, etc. and the rest of the motor will not be getting the oil that it needs to function.

You will soon have a reason to buy that new four stroke Yamaha that you know you really want. We can help you make the selection of your new four stroke. Former HPDI owners have really been impressed with the Yamaha SHO motor.

[TRICKY1121]

so I guess you don't recommend doing that? I was hoping to see if the oil injection system was the reason i'm finding oil in the intake manifold on the front of the motor and extremely greasy plugs which is causing my motor to not run to good

[99yam40]

so I guess you don't recommend doing that? I was hoping to see if the oil injection system was the reason i'm finding oil in the intake manifold on the front of the motor and extremely greasy plugs which is causing my motor to not run to good

Did you not read what he wrote about not getting any oil to vital parts of the motor?
You need to understand where the oil is injected on HPDI motors, it is not just in the fuel.

Time to find out what is wrong with the motor and fix it properly

[boscoe99]

so I guess you don't recommend doing that? I was hoping to see if the oil injection system was the reason i'm finding oil in the intake manifold on the front of the motor and extremely greasy plugs which is causing my motor to not run to good

Exactly. It is not recommend. Unless you are ready for the motor to die an early death. Would be like my wife's car dripping oil on the garage floor. I guess I could drain all of the oil from the system and it would not drip oil. She might be getting the new car she wants sooner rather than later.

Tell us exactly what you are seeing/feeling/hearing/smelling and when you sense it all.

Which plug? One of them or all of them?

It is normally for some oil to get into the intake silencer. The oil pump link rod connector has been known to wear out and break in which case too much oil is pumped to the motor. That could be part of the problem.

Give us the complete model of your motor also please.

[TRICKY1121]

it is a VZ 225 TLRD 3.3. originally I couldn't get the boat on plane one day so I changed the fuel filter plugs and new screen in the vst. no improvement. changed out both low pressure fuel pumps and a new strainer, put the boat back in the water and still no real improvement.got home and pulled the plugs again that was when I realized they were wet and greasy, all of them.

[99yam40]

do you know what the fuel pressures are doing, or are you just guessing and throwing parts at it?
troubleshooting is the best and cheapest way to do things

[TRICKY1121]

don't know what the fuel pressure is doing. not really sure how to check it but I can go buy a gauge and give it a try. do I need a specific fuel pressure gauge or one from an auto parts store work

[boscoe99]

don't know what the fuel pressure is doing. not really sure how to check it but I can go buy a gauge and give it a try. do I need a specific fuel pressure gauge or one from an auto parts store work

You can measure the medium pressure pump output with a fuel gauge from an auto parts store. That will tell you part of the story. Normally you start there and if you have rated pressure you then suspect the high pressure pump may have insufficient fuel pressure.

The fuel gets sent from the medium pressure pump to the high pressure pumps. It gets boosted to nominally 1000 psi. Not recommended to use a mechanical pressure gauge to measure pump output pressure but some have done so. A laptop PC loaded with Yamaha software can measure and display high pressure pump output. Getting the software can be hard to do and is an expense.

The HP pump can be serviced somewhat by a DIY'r (internal filter change) but if it needs to be rebuilt it should go out to a shop that specializes in this.

Measure the fuel pressure and get back to us with the results please.

[TRICKY1121]

I checked the medium fuel pressure and it was dead on the numbers you gave me. Do you recommend taking it to a Yamaha dealer to check the HP fuel pressure?

[boscoe99]

I checked the medium fuel pressure and it was dead on the numbers you gave me. Do you recommend taking it to a Yamaha dealer to check the HP fuel pressure?

Yes. Dealer can run the motor while monitoring the HP pump output.

If the HP pump is found to be at fault you can have the dealer arrange for it to be serviced, you can remove it and send it out for service yourself or if you are handy you can remove and replace some filters embedded within the pump to see if that solves the problem.

If you want to try the latter you can review this tutorial to determine if this is something that you want to do.

3.3L hpdi secret filters removal

[rodbolt17]

you must check BOTH fuel pressures at the same time AT the failure load and RPM.

anything else is typically a teat on a boar hog.

you don't need YDS to test the HP pressure.
a DVM and the service manual and two paper clips will work just fine.

[boscoe99]

you must check BOTH fuel pressures at the same time AT the failure load and RPM.

anything else is typically a teat on a boar hog.

you don't need YDS to test the HP pressure.
a DVM and the service manual and two paper clips will work just fine.

Or you can improvise and install a mechanical fuel pressure gauge to monitor HP pump pressure. Or an electronic fuel pressure gauge.

There are always several ways to skin those cats.

[99yam40]

that high of pressure on HP pump, it is probably better to measure voltage or hook up to a computer