VMAX 175 HPDI Fouling plugs

[xnodakkid]

I have a 2002 175 VMAX HPDI bought it in Feb. of 02. I put about 30-40 hours on the engine and had it serviced by the dealer in the beginning of July and every thing was just GREAT. The motor ran great up until a fishing trip during the middle of August when it started to miss and I could only get about 4800 RPMS out of the motor.
I took it back to the dealer and he stated the engine had fouled plugs. The machanic suggested I use a gas additive every time I put gas in the tank to correct the problem.
I did not idle a lot with the motor or do anything out of the ordinary. I have a kicker motor for trolling and I don't tow anything with my boat.
This has only happened once up till now, but I was wondering if anyone else has had this problem and if so is there an ajustment that can be made on the motor or something else that can be done to avoid putting in the additive every time I top off my tank and have to calculate the correct additive amount. Any Advise would be appreciated, Thanks.

[Woofer]

I have a HPDI 175 and exp. the same problem. Check the sending unit from the engine mounted res. If that is sticking it will cause extra oil to be pumped form the main tank to the res on the motor, the over flow is then pumped right into the intakes of your motor causing it to foul.

Woofer

[dl;homes]

I have same motor same age- no problem! Only problem was the sending unit wouldn't send oil had to manually pump resivior up until they got a fix. maybe your dealer did'nt get the right fix. Buddy had same problem as mine so there must have been a glitch of some sort in that batch.

[fishhunter]

Not trying to start anything here but anytime some has a question about an optimax they are told its junk, One thing I can say is i've had zero problems with mine and dont have to use a gas additive or ring free every tank like all Yamahas.

[T-Mac]

Any little piece of crap can foul a plug and typically, if one plug is fouled on a correctly propped V-6 outboard...............approx. 4800rpms @w.o.t. is the result.
I fouled one in Oct. 2000 on my 200 own HPDI. I can only remember seeing one other in all the HPDIs we have sold since their inception.
So, I'd have to say it is NOT chronic....but rare, actually.

[Sling Shot]

Come on fishhunter your reaching on this one. Optis are crap, on a percentage basis. Anyone that uses percentage basis knows, Yamaha HPDI is far superior then OPTI's.

[PJM]

xnodakkid

I need to know what kind of gas are you using, regular, premium ect?
Then I will post back.

[Fitch]

I heard they had some problems with the motors and have increased the fuel pressure for 2003. Both Opti and Ficht DI recommend spark plug changes every 100 hours. Has to do with the kind of combustion they do in the engine.
How does direct-injection technology work? As the name suggests, it is based on the concept of directly injecting fuel and air into the combustion chamber. Current fuel-injection technology uses an injector located at the intake port of each cylinder, which is why it is sometimes referred to as port fuel injection. This injector sprays fuel into the port area while air, coming from the intake manifold, sweeps the fuel into the combustion chamber. Compared to carburetion, fuel injection is more advanced and offers greater control over the intake charge mixture. But, compared to direct injection, fuel injection is sloppy and imprecise.

By contrast, a direct-injection system allows exact control over not just the amount of fuel entering the combustion chamber, but when the fuel enters the combustion chamber. It even controls the shape of the fuel charge and the flow of air inside the combustion chamber! The benefits of all this precision can get pretty complex, but the short answer is that direct injection allows each tiny fuel molecule to be used with maximum efficiency, thus resulting in better horsepower and gas mileage. It also allows for a complete fuel charge burn, even when unburned exhaust gas is re-circulated back into the combustion chamber, which means reduced emissions and cleaner air.

[xnodakkid]

PJM

I have only used Premium gas. That is what the manual recommended.
I hope that helped.

xnodakkid

[fishhunter]

I would just like to know why Yamaha and Yamaha only recomends to have premium fuel and ring free or another additive added to the fuel in every tank while the other DFIs can burn standard fuel with no addative. By the way I would love to see those percentages your talking about considering merc sells more motors than all the rest combined.

[Erie Addict]

Please Post these"percentages". There are alot of happy Opti folks that would love to see them.

[Dwayne]

I have a 150 v-max hpdi and my manual includes the 175 and it says " Recommened gasoline with a minimun octane rating of 86 ( pump octane number ) " This to me is far from premium.

[PJM]

xnodakkid

Here is something you should know. Yamaha test there engines with regular fuel and I was told this from a factory tech. I have a Yamaha that I started out running premium fuel and I was fouling plugs. The reason I was told is that premium gas burns colder then regular gas and along with running a BR9HS NGK plug which for the most part is a cold plug, I was not running hot enough. I could go down to a hotter plug but then I might be asking for trouble. I switch to regular fuel and the problem went away. Running the hotter regular fuel will also keep yout OX sensor cleaner. IF you go to a good Yamaha service tech he should know this. It's safe to say that that almost all new motors are designed to run on regular fuel.

[xnodakkid]

Thanks for all your help. I will use Reg. fuel, thats sounds like it will solve the problem. Thanks again.

[smittin]

I was wondering how much do new plugs cost for an opti?
I paid less than twenty bucks for a set of six!

[T-Mac]

regular is what HPDI calls for...... 87 octane.

[T-Mac]

Fitch... are you referring to Opti and Ficht getting more pressure?

HPDI is the same..except on the new 250 which is a totally new engine and does have higher pressure than the others.