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Random Quote: I never hold a grudge. Once I get even with the SOB I forget the whole thing.
I contacted Yamaha about the issue of my motor fouling plugs in less than 10 hrs and asked about any update for this issue! Their response was there is no update except the saltwater intrusion update but give me your serial # and lets look. She said there was nothing in the computer that showed this motor was in need of an update. Since then I fouled another set of plugs and brought the motor in to be checked. The mechanic called yamaha and told them of the issue and they gave him some instructions on making some minor adjustments and hopefully it will resolve the problem. I said ok lets try anything to fix this but we were both wondering how the adjustments they advised would help with fouling plugs. So I bring the boat back in for the adjustments and I got a call from the dealer saying that yamaha called them to say they are sending the intrusion kit for my motor. The dealer said it was my phone call that prompted them to send the update. I am glad to see the prompt response from yamaha but I don't understand the relationship between fouling plugs and saltwater intrusion. Hopefully they can get all of the problems resolved. JJ
Why does saltwater intrusion signal the computer to dump oil??? Last weekend I burned 72 gallons of fuel and 1 1/2 gallons of oil. Thats 48 to 1. I'm not sure but I don't think it's over oiling.JJ
do a search and look for some of buck wild's 300 HPDI posts - I think he explains it pretty well - it has something to do with the saltwater altering the air/mixture to where the computer thinks the engone needs more oil...
but I fully admit I'm over my hrad here...but I remember what I read pretty good...
Glen etc, this may make sense. One thing a local wrench was telling me about my motor is it looked like water had gotten in somehow. IE burned lean or water.
I definately noticed a tendency for this motor to foul more rapidly on rough days. Not sure why.
Great point!! I keep thinking this is not an over oiling situation but after doing a search it seems that some people think the salt water intrusiion can somehow foul the plugs!! This motor is on a 25' bay boat, not a contender etc. that has the baitwell problems. Maybe I have running it submerged and did not know it!!JJ
i took mine to R6 naval tower last week and the transducer came loose and water came into the motor. One the way back when we ran wide open the motor skipped (plug-fouling) after that the next day call mech. and we ran it needless to say it was perfect. He said that its ok for a little spray but when the transducer came loose it completly drowned the motor causing salt to hit the plugs. O by the way we caugh some fish to.
__________________ 23' key west W/ Yam 300 V6 Four Stroke
GO GATORS!
Ok here you go sent our 300 in for the upgrades running good with 308 hours other them some plug fouling every 75 hours its been strong. Tech finds a bad base gasket has been letting saltwater in under the cowl. Yamaha says brand new fully dressed powerhead for you. back to zero hours new ECU and everytyhing else will be breaking her in again this week. With all the hubba about the 300s I have been very happy with the preformance and fuel burn allmost 3mpg under the right seas on our 23T Contender. Thanks Yamaha
My dealer (mechanic) just called me and said I am getting a new powerhead (on one) and saltwater intrusion kits for my motors on my 32 Reg. I don't think this problem is all about the Contenders live well. Motors have just over 300 hrs.
Can someone summarize the status of the 300 HP HPDI reliability issues, for the new buyers to know first hand if the current production has been upgraded or if the problems on current engines still persist. Also, some owners have complained about multiple powerhead replacements, is that still common today. It is a shame that Yamaha has done such a lousy job informing consumers about the issues with these engine, people buy Yamaha for their reliability, and they have lost credibility big time with this one. At least there is THT to spread the word, even when one has to separate the truth from the gossip.
34 hrs, fouled set of plugs - they adjusted the oil rod (refused me the full update).
Now, 45 hrs, rough idle, threated to die twice yesterday bringin her over 4K.
Here we go again.
__________________ Current:
19' Alcar cc
24' Grady White Explorer
...and a blow-boat to be named later
Ok here you go sent our 300 in for the upgrades running good with 308 hours other them some plug fouling every 75 hours its been strong. Tech finds a bad base gasket has been letting saltwater in under the cowl. Yamaha says brand new fully dressed powerhead for you. back to zero hours new ECU and everytyhing else will be breaking her in again this week. With all the hubba about the 300s I have been very happy with the preformance and fuel burn allmost 3mpg under the right seas on our 23T Contender. Thanks Yamaha
While you are thanking Yamaha, thank them for an engine that has lost more than half it's value when you go to sell it or trade it in. Even insurance companies want to seriously devalue the engine if there is a loss. Several folks on this forum have the updates completed and the engines still blew power heads. They have no confidence in taking the engine off shore. The 250/300 HPDI engines have a terrible reputation. Only because Yamaha tried to deflect the problems.
Jesse - The higher HP HPDI's have a two stage oiling system, both mechanical and electrical.
While the mechanical pump does the majority of the oiling. The 250 and 350 HPDI also has a solenoid pump assembly PN 68F-13100-00-00( 300Hp) which tees off the feed from primary tank. Guess what guys it's ECU controlled! There are basically two oiling systems in these high HP HPDI's. The pump solenoid adds oil to the VST, while the mechanical pump introduces oil to the reed valve plate. So yes more oil can be introduced in to the VST tank, combine that with the reed valve mechanical oiling, you can have over oiling!
Hopefully anyone getting the kits installed by the dealer, has a dealer that is well trained. These kits are time consuming and if the tech is not too savvy, it could lead to problems. Yamaha at one time would only let a few dealers install these kits based on training and knowledge. They were sending out factory reps to do it!
KevinM - 8/1/2005 5:28 PM Jesse - The higher HP HPDI's have a two stage oiling system, both mechanical and electrical. While the mechanical pump does the majority of the oiling. The 250 and 350 HPDI also has a solenoid pump
I WANT A 350 HPDI
This is new news to many of us... but it does explain a lot of weird issues we have been bantering around...
I have a 2003 300 HPDI. I am happy with the performance but I do foul plugs around 65 to 75 hours. My mechanic has said he is contacting Yamaha about the salt water intrusion fix. What should I do or follow up on to make sure that the fixes are done right or the correct ones are done. Thanks for any advise.
Kevin - I thought that the solenoid pump's only job was to give enough oil to lubricate the injectors!! Could this be enough oil to over oil and foul plugs. I'm not sure but remember I am getting between 45:1 and 50:1. Do you know if the update kit has a new ECU? Also this will be the first update installation for this dealer, I am confident in their ability and sure it will be done right. Not sure if the factory rep will be there. JJ
300 hpdi update 
