F-150 4 Stroke Problem

[T.Z.]

Hello to all.. I have twin 150 4-stoke, Yamahas. I have 110 hours on each. I bought them from Alafia marine .They also mounted them.I took it in for the twenty hour and the one hundred hour tune-up. They both ran idenical. Both WOT at 5800 rpms.When I picked it up from the one hundred hour tune-up,the next trip out the port motor only reached 5000-5100 rpms. And it also shakes at idle.It seems like it runs rough.Ive brought it back 3 times and they say there is nothing wrong with it,when I know there is.They said when I brought it in for my 100 hour tune-up my water fuel separaters where full off water. Mabye they where,butit seems like if that was an issue it would effect both motors. I dont know what to do at this point,Im pretty frustrated after spending 600 dollars on the tune-up,when both motrs ran great.Any help or direction would be Greatly appriciated. Todd Zernick. Tampa..Fl

 

[bigbrownbuku]

Re: F-150 4 Stroke Problem

does your tank have 2 pickups or 1? if its 2 most likely all the water goes to 1 filter.<br /><br />clearing the water from the f150 is a fairly quick job, all the parts are modular. dont continue to run it while it runs poorly, sometimes four strokes will suck a little more then they blow.<br />fuel pump and all fuel lines need to be cleared. fuel rail needs to removed completely and cleared<br />injectors need to be cleaned.<br />vst needs to be dismantled and cleaned<br />all the replaceable fuel filters need to be replaced.<br /><br />yamaha left a nice little 3/4 inch cup in the bottom of the fuel rail that collects every little molecule of water that travels to the rail.<br />if you dont get all the water it will accumulate here and begin running poorly soon after the first try.

 

[rodbolt]

Re: F-150 4 Stroke Problem

could be some water/debris is in the vapor seperator. seems they put a very fine screen mesh filter on the bottom of the high pressure pump. it takes an act of congress to access it so no one does.methinks yanaha and merc dont wish the public or the techs to change it, the manual is rather vague on VST service intravals on the 4 stroke VST but say to clean and inspect the 2 stroke VST every 100 hours OR once per year. same design almost the same filter same pressure but no mention of it due the the inability to service it yet it must be done. so like BenC says it may be time to find out if the water got past the seperator, the seperator will only hold so much then it will pass it on.

 

[T.Z.]

Re: F-150 4 Stroke Problem

Thanks for the replys guys. Im wondering if this is something I could do. All the marinas are backed up,at least 2 weeks. How service hours would something like this take, at a marina? It sounds expensive. To answer your question, BenC I have 2 pick-ups with 2 Water-fuel separaters, One tank. After the tune-up I checked the oil level,it was over the F about a half inch,could that Inhibit the performance of it?

 

[rodbolt]

Re: F-150 4 Stroke Problem

not really but it does show a level of incompetence.<br /> try to keep the level half way between the top and bottom marks. you can open the drain on the vapor seperator and look for water in it. do you have an itemized list of the service performed?

 

[bigbrownbuku]

Re: F-150 4 Stroke Problem

boats never sit level, so any water in your tank always goes to the heavy side. the vst on the f150's isnt that bad a job to get at. fortunately i had 2 last year with water in gas tank problems that led me to cleaning this system. dont try and do this job yourself. its not completely necessary, but, a vacuum/balance test when the manifold is reinstalled is kinda important. be patient and book a time to have this done by people you trust.

 

[T.Z.]

Re: F-150 4 Stroke Problem

Im getting a list of everthing they did,as far as there tune-up procedure.Im going to pick the boat up today and will look to see if is any water in the vapor separater.Ill post back and tell ya what I find. Thanks again for the replies. Im starting to feel a little more confindent,in getting thi resolved...