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I cant believe that my new engine already had a problem. Lost both of my trips this weekend because of it. Looks like the secondary fuel pump failed after 163 hrs. It just totally lost fuel pressure. The good thing was that it would idle so I could get back to the launch but anything above an idle it would lose pressure and die. Anyone else have this problem?
 

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A common problem is debris or corrosion inside the vapor separator tank ( VST ) that gets stirred up and plugs up the internal electric fuel pump filter screen, thus a loss of fuel pressure to the injectors.
 

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A common problem is debris or corrosion inside the vapor separator tank ( VST ) that gets stirred up and plugs up the internal electric fuel pump filter screen, thus a loss of fuel pressure to the injectors.
Yes this is the only common problem we see with the pumps, is geeting trash in the pump screen and it gets by the filters.
 

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Most of the yammah 4 strokes there is a horseshoe, or u shaped filter, after the electric fuel lift pump. THere is one on the bottom of the vapor sep. tank, that filters the fuel before it goes into the VST pump to raise fuel pressure to around 40 pounds, to the injectors, not at the shop to look at service book..
Some of the fuel Adatives, that are sold will clean the fuel tank and it ends up in the fuel filters, As does the Gas with ethanol it cleans everything it touches and ends up in the bottom of your fuel tank, and in your engine.. Had a different shop talk some customers , who had a older boat and tanks, in using the new best product he just started being a dealer for and we had to replace the filters once a week for a month, after the product cleaned the fuel tank so good it went straight into the filters and engine, remove the VST tank and clen the rilter in it, also, it cleaned all the fine particles and they can only filter the fuel particles so small around 10 microns, if they use samller micron filters it starts to cause fuel restrictions, and causes running issues with the engine. So not that it is the engine but the fuel , addatives, that are added, it the boat is a older boat that was rerigged with a new engine, the dealer doing the maintence, the owner taking it in or doing the proper maintence. Yes I'm a Yamaha dealer, no there is not a perfect engine that never has problems no matter what brand, they all have thier own small problems. They build them for the fuel specs, at the time of design , but the fuel changes before it engines hit the markets, the fuel is blended, sits, down a pipe line, in more strorage tanks, in trucks, in the gas station tanks and then in the boat fuel tank which is vent to open air, so there is so much transfers, sitting, different pipelines, tanks trucks storage tanks for it to pick up small pieces of trash, junk before it ever gets into a boat tank, that may be mised with older fuel, The fuel now only has a shelf life of around 30-60 days and it may be that old before you get it? The fuel filters are the customers only line of defense, so change the them often, all fo them to help keep todays, EPA engines running right.

The Alcohol in the fuel is powerfull cleaner and loves to suck up moisture, We use to run a Jr Dragster, a 5 hp brigs block pumping out over 40 hp, on pure Alcohol, had to keep a New Sealed 55 gal drum on plywood or it would suck the moisture out of the conrete thru the metal drum and fail fuel test at the track, HAd to change the oil every 3 runs down 1.8 mile track, full of moisture. Take some fuel out of you boat and set in a open glass container, and set out side for a ,little while in a hour or so it will be cloudly from the moisture it pulled in from the air! Esp. if gas from a EPA area that has ethanol.!
 
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