2000 VMAX (V150TLRY) - Fuel Issue ??

[Pencil1062]

Yamaha 150 VMAX - Carburated, installed on Skeeter Bass Boat. I bought it new in 2000. Mfg date stamp says 4/99, but Yamaha parts pagees list this motor number as a 2000. I have alwasy used the boat fairly regular, until year before last, it had no useage for 18 months (20 gals of fuel on board).. Added more fuel, and the motor will start very easily, idle fairly well, and run out up to about half throttle, then starts cutting out. Have replaced plugs two times. (they do appeared fouled a bit). The motors angle sems to have impact on its rpms and running (thus I do not think it is electircal). If at full throttle I hit the choke it will run up the rpms for a fews seconds.. If I can get the motor working easier by coaxing boat onto a plane, then it will run out at about 60% of what is normal. I just drained the fuel tank completely added new fuel. and still the same issue, and runs worse as the plugs foul more. This AM remove the filter bowl, and found that there is NOT a screen in it?????? Ideas?? where to run?? Thank you,

[rodbolt17]

clean the carbs and replace both fuel pumps.
preferably BEFORE you smoke a piston from running lean.

[Pencil1062]

Pretty much figured it was heading that way... Thanks... On the carb cleaning?? How extensive ?

Thanks again

[Tucker]

Get on the parts.net parts menu for your motor. Rebuild kits are available, pretty reasonably priced. Be real careful with the pilot needle adjustment. It has a real fine point on the end that a lot of guys bend because they run it in too tight when adjusting. Get a shop manual.

[Pencil1062]

Parts.net brings up some other page and send you astray... that aside. The Fuel Pumps for this motor (2 of them) are classified as Obsolete....... that said, do I buy all the internal parts (havent found a rebuild kit for the pumps) and just rebuild them??

Shop manual will be ordered shortly........ once I locate one... grin

[Tucker]

No way the pumps are obsolete. Bobby will chim in with the direct link.

[Pencil1062]

This AM Update... Disasembled one of the Fuel pumps.. It looks clean and in great shape... no ugly matter buildups of any sort, diaphrams look to be solid... Where would the issue be, if this motor has been lacking the screen in the water seperator for a few years.. (my original first service might have seen it removed and not replaced by the dealer???).

Took the top carb off, and removed the float tank... floats seem to be moving freely etc.. there is a bit of discoloration in tank bottoms... Where would the issues be in the carbs?? Or is this a spray carb cleaner, blow it out with air, make sure a new filter screen is installed, reasemble and test run??

I do have a fairly extensive mechanical background, (just cannot type worth a crap)... grin..

[Tucker]

Not sure what you mean about a filter screen. Filter element?? Think you need to take all the carbs off and clean out the jets.

[Pencil1062]

The Filter Element that is supposed to be inside the Filter Cup (water seperator) prior to the fuel pumps.. Evidently this was removed during the first engine maintenance way back in late 2000, and the shop did not replace it... (make one say....... hmmmmmmm)

[Pencil1062]

Just spoke with the local parts/service dealer for the Yamaha motors like this, and was told that ALL 3 Carbs have to be removed as a ONE peice unit, or no matter what you would screw up the linkage timing....... True/False??

He also stated this boat should have been equiped with a transome mounted water sperator.... (this I can appreciate, and will install one myself)

[99yam40]

it is always best to do the link and sync after reinstalling the carbs no matter if you pull all or one.

It would also best to do all carbs and lines to make sure nothing hits the carbs again right after cleaning carbs

[rodbolt17]

take the carbs off one at a time.
remove the air box.
remove the manual and electrical choke linkage,dont lose the oring.
unclip the oil link rod from the lower carb.
remove the throttle link carefully,I use bent nedle nose pliers.
remove the 4 nuts holding the top carb on,remove the carb and cut the tie strap and use pliers to PUSH the hose off.
remove the hose from the upper pump outlet.
repeat as nessasary until the bottom carb is off.

[Tucker]

Wait a second Pencil, are you saying you had no filter (engine or boat mount) since 2000??
Can't believe you went this long without problems. The RB is spot on and: Do one carb at a time. Search the RB's posts about his carb overhaul procedure. Use the zip ties with radius buckle for hose. Most places don't sell them, have to go to McMaster Carr. Get the book to do the link and sync.

[200090tlry]

Plan on spending some money and time

Your outboard deserves it, water pump,thermo + gaskets, clean out carbs,check all fuel lines and even little oring that quick connects to motor mine was missing and allowing some air in system. For good maintance replace the fuel pump diamphrams or order new pumps hey why not at least you can rule it out. If it's never been done just do it. My suggestion is order the parts now so in week you will have them. If your taking off carbs take your time and have some tools ready to go. Use correct cleaner, carb cleaner is really toxic and for outboards can do damage to plastic. I think CRC makes a few cleaners for MAFs that is safer to use.

[Pencil1062]

You guys all rock... I want to thank you all for the input.. My experience is in Diesel motor mechanics, and I can do those with my eyes closed, at least one eye closed. Money spent isnt an issue, and the engine layout all seems pretty simple, I do have all the right tools, so no issues there, and a great shop facility to do it in... so if nothing else it will be a fun learning experience.

In answer, NOPE!!! evidently no filter in it since early 2001, and that blows me away that they removed it and did not replace it.. Installing a new inline water seperator pre motor as well to make sure it doesnt happen again, as well as using stabalizer (Thats my bad too) I didnt realize what the ethanol issues were, and found the dusty build up in the top carb...