Have a 4 stroke 115 yamaha on a 17 sea hunt that would only run about 41 normal is around 50. after a few minutes at wide open boat would slow to about 32. Was told to change vst filter. Did that and now boat won’t plane out runs about 10mph. Idles fine changed plugs no difference. not sure how much pressure should be on the fuel rail but when I push dn on the valve it just trickles out of the rail. Idles great but when out of the water when I advance the throttle it stalls then catches up. not sure what else it could be. Fuel pump primes up when I turn on the key. Any ides?
Take it to Mike Murphy @ Hanckel.He’ll fix you up.Something is likely still not right in the vst.It could also be carbon build up on the injectors and one or more are not opening properly.I had this on the same moteor and used the reccomended de-carb procedure with Ringfree and it took care of it.Be sure to change oil,oil filter,and plugs afterward. good luck.
“Modern day Robin Hoodism-Steal from the sucessful and give to the poorly motivated.”
my uncle has the same problem. i cleaned the VST(which was nasty) and changed the vst filter, changed the primary fuel filter, inline fuel filter from the fuel pump to the vst and it still does it even on a seperate fuel tank. i checked the injector resistance which was good, but there are small filter screens on each injector which i did not do. i’m hoping that is the problem. let me know what you find and i’ll do the same.
it’s tough being a gamecock fan!
Same issues on a 2006 F115, resolved by changing small inline filter above vst, its in a black boot…changed to an aftermarket filter, yamaha sells as a “package”.
STRAY DOG
46 OY
26 EVERGLADES
18 HEWES
That’s the one i was saying was the one from pump to vst. it comes with the hose attached. wish that was our problem.
it’s tough being a gamecock fan!
Finally got pressure on the fuel rail, had tons of air in the fuel. However ran boat again on the water and still won’t plane out. It seems to me that its sucking air somewhere. I bled the rail again and it still has air after several bleeding attempts.
“The Best thing about Fishing is your guaranteed to get your worm wet”!!
put a clean line between the primary filter and the fuel line, so you can look for air bubbles, but I doubt thats your problem.
if you were sucking air, it would plane off great, and then lose power
sounds more like a clogged filter
you have about 7 filters on that motor
Also replaced fuel lines from tank to motor, lines were old and brittle, could see inside liner flaking off, eventually clogging filters, I replaced the inline filter twice…once with the yamaha, ran fine a couple hours and again was full of trash, replaced with a quicksilver inline filter ( a little larger ) and has worked fine since.
Another motor had a pinched fuel line where the line runs through the rubber gasket into the motor, salt had built up and pinced the line, motor would not turn over 2500rpms before it would begin to surge.
Good Luck, let me know what you find.
STRAY DOG
46 OY
26 EVERGLADES
18 HEWES
Can u get to the in-line filter by just pulling off the silencer or do you have to pull intake man as well? My only concern is boat would run 40 mph before I changed vst filter now maybe 10 mph. Just seems like I caused the problem. Just trying to analyze the problem. I did pull the main fuel filter today and there was dirt in the bowl. Going to replace that filter for starts I guess then maybe the in-line filter as well. Would a diagnostic determine this problem ChrisV? Also do you Carry that filter Chris? Really appreciate everybodys help also!!
“The Best thing about Fishing is your guaranteed to get your worm wet”!!
that filer runs from the fuel pump on the back of the motor to the top of the vst. it’s easy to get off the pump side. just take off the silencer and see. you probably could.
it’s tough being a gamecock fan!
in side of the vst is a really fine filter in the bottom of the fuel pump. if you takeit off and look at it it will look clean but most of the time they are clogged. ive tried cleaning them out before but it doenst work. better off just getting a new one for 40$ and be done with it. i have a 150 yammie fourstroke and had the same problem last summer. its easier to do on a 115 since the vst isnt buried.
197 poineer F150
Did the compression check and all clylinders checked good. Going to procede with the filter changes and then maybe look at the injectors. Thanks to everyone for the help??
“The Best thing about Fishing is your guaranteed to get your worm wet”!!
quote:
Originally posted by harbor shocker its easier to do on a 115 since the vst isnt buried.
f115 vst is behind the intake manifold i think
I think in his earlier post, he already replaced the vst filter, but he didnt replace the inline filter
Had the injectors cleaned at Charleston Marine. Great price and a great job!!! Also replaced low pressure filter and the boat runs better than new!! Thanks Chris V and everybody for your help!! Charleston Marine is a Top notch repair facility. Will be the only place I ever do business with again!!!
“The Best thing about Fishing is your guaranteed to get your worm wet”!!