Yamaha SS 2 Stalling problem

[boatino]

Hey Guys,

I was running my GW marlin a month ago and decided to switch from the main gas tank to the Aux. gas tank. The boat went a mile and died. I switched back to the main but still needed a tow to get in. Upon inspection of the fuel water separators I noticed some water. I bought every fuel additive known to man, startron, stabil, dry gas, k100. I changed out the separators along with the fuel filters. Still had some water after running at the dock and the motors stalling out again. Dumped the separators and fuel filter. Proceeded to open up the main tank & Aux tank at the sending unit. Using a dipstick oil hand pump, my son and I siphoned out 1 gallon of bad gas off the main and 2 gallons of bad gas off the Aux tank. Restarted the boat at dock and it ran great for 1 hour at 500-3000 rpms. I even put it in gear and ran it up to 1200 rpms without stalling. We were pretty proud of ourselves until we went for a ride that evening. We went 300 yards and the port engine goes down. Then another 100 yards back towards the dock and the starboard engine dies. Checked the separators this morning and they were clean. I replaced them anyways after finding a couple of drops of water in the starboard engine's fuel filter. I've been reading up on the VST and other part replacement but is this just a case of bad gas? Shouldn't the 10 micron separators be catching it before getting to the engines? How much water will those Yamaha Fuel water separators hold? I'm only getting a shot glass of water out of them and the engines are still cutting out. Is the fuel injection on these engines that finicky? Please help as the local yamaha dealer doesn't want to work on 2 stroke motors according to their service manager :bang .

Thanks in advance for the help.

John

 

[Pay2Play]

From what I have read the vst is 2 micron. I have a carb sws and am running a racor 2 micon main filter separator. I would recommend...draining the tanks completely, searching the internet on removal and cleaning of filters on your type of motor (that other forum does have alot of good info) I think its been covered on here also, and going with a 2 micron main filter rated at flow that your motors require. Also if your using E10 fuel check your fuel lines, or replace them.

 

[Tucker]

Yep, the OX66's are very picky about their fuel. You still have water in the VST and probably the fuel rail and maybe the onboard fuel filter. Sounds like you also have water in the fuel tank I've been there and there is no easy way out. This is what I would do:

1) Confirm the problem.
A) Drain the VST, and onboard fuel filter (The onboard filter is a PIA to get back on. Ethanol swells the cap)
B) Remove the check valve between the fuel filter and LP fuel pumps.
a) The valve has flats on both halves, separate and throw away the guts, reassemble. (that check valve is nothing but trouble)
C) Disconnect onboard fuel lines from the waterseps and run boat on remote 5-gal tanks
D) Gotta empty the tank(s)
a) No easy way of doing this. I put mine on the trailer and syphoned all the fuel out. (ran fine in the tractor)

OR, If your confident that your main tank is fine, run off that and not the aux. Drain aux during off season.

2) Make sure it doesn't happen again (hopefully)
A) Replace the o-rings on the fuel fill caps. (Perco sent me replacements free)
B) Replace 10 micron Yam filters with a 2 micron Racors (filter p/n S3220SUL, bowl p/n RK30473-02)

 

[boatino]

Tucker,
The on-board fuel filter and bowl has been the easiest thing to replace as I have had them on and off about 10 times checking them & draining them. The VST sounds like a big job based on what I saw on line last night. I was told not to use the Racor filters with the clear bottoms in the bilge area. They are suppose to only be used in an open environment. Not sure how true that is but it would make it a whole lot easier to check for water than trying to unscrew the yamaha fuel water separators constantly. Does anyone know on a 2000 GW Marlin what the actual shape of the gas tank bottom is? I know they seem to be baffled on the port and starboard sides but not front to back. It's hard to see all that well looking through a 1 1/2" diameter hole in the top of the tank. If I do attempt the VST removal do you recommend doing this out of the water? Man I wish more freshwater boats ran Yamaha outboards then we might actually get some dealer support....

Thanks,

John

 

[Grog]

There's always arguments but if you have outboards the clear bowl is OK.

 

[Tucker]

Boat,
That 2nd Racor p/n is for a metal bowl. First p/n is the filtersep, It's a 2-piece filter. For now just drain the VST tank, Should be a brass drain screw near the bottom. Yea, the VST HP pump filter should be cleaned but first things first and I would just drain the tank if you're sure water and not dirt is the problem. Are you running Ethanol fuel? Please keep us posted with developments.

 

[grady33]

I have only used non ethanol fuel and have not had any problems. Change filters annually.

 

[boatino]

Ok I drained the tank (VST?) on the port side of the engine there is a brass flat head screw there. Gas oil mixture seemed clear with no water present. I have been using marine gas only. The last purchase in May of this year was supposively non ethanol fuel. I have recently heard through the grapevine that this marina is know for having suspect gas. (Always the last to know.) After draining the VST tank the engines would only run for seconds before shutting down. I'm beginning to worry that I might be doing more damage than good. I'm not seeing water in the separators or onboard fuel filter. I am going to try a portable tank tomorrow to see if I can get the engines running. I might be buying a trailer as I have found someone 35 miles away that will work on it but only at his shop. Has anyone tried the funnels with filters built into them. I hate throwing away 200 gallons of gas... I've also tried to find someone in my area that does fuel polishing but haven't had much luck. I'm in upstate NY (Rochester) if anyone knows of a fuel polisher in the area please contact me through the site. I am also contacting Perko tomorrow about new o-rings for the gas caps.

Thanks,

John

 

[boatino]

Hey everyone, engines are finally fixed. I had the boat shipped to a marina about 50 miles away. They changed the VST filters the boat would only run up to 4000 rpms then stall out. They replaced the 3 fuel pumps on each engine and that solved the problem. I did notice while running it home the other night that I wasn't getting the complete fuel flow readouts for both engines together on the gages. They were only showing 1 engine for fuel flow. Either that or my 2000 GW Marlin is now getting 2.5 mpg at 30 mph. (I wish) Did the marina forget to plug something back in for the gages? Happy again!!

John

 

[Tucker]

The fuel flow sending units are after the fuel water seps and before primer bulbs. Simple connection to check. Chances are your sending unit is bad. Believe they're about $130.

 

[boatino]

Tucker,

They were working fine before the mechanic worked on the boat. Come to think about it they replaced the primer bulbs could they have disconnected or broke it then? Is it simply a wire from the fuel line to the gage to get the reading?

John

 

[Tucker]

The sending unit is piped via hose after the priming bulbs. There is a 3-wire harness that plugs into a cable usually running in a hard rigging tube back to the console. Pull it apart and spray some WD40 in the connection and see if that helps.