95 70hp force bucking over 2000 rpms

[speeddemon1452]

well boat was running good now this.on way back in started bucking bad hole boat is julted wene it does it.everything is new spark plugs all new fuel lines and rebult the fuelpump. don't think its a missfire becouse motor sounds same as its bucking just that its jumping bad hope someone can give me some posible things could be so i can check it out before it gets to be something expensive .

 

[roscoe]

Re: 95 70hp force bucking over 2000 rpms

IT likely is in the shift linkage.<br />Perhaps the couple or the locking nut has vibrated loose, its located on the starboard side and connects the upper shift linkage to the shift shaft. Its a bit touchy to adjust so that you have both forward and reverse gears.<br /><br />If thats not it, it could be a worn out clutchdog (cog type coupler) that engages the gears in the lower unit. The corners get rounded over and it will not stay engaged. Often times a machine shop can reface the surface and the part can be reused.<br />Or on some models, it can be turned around-installed backwards- so that the worn surface is engaging the reverse gear, which is used at lower rpm.<br /><br />The longer you run it in its current condition, the worse the damage.

 

[speeddemon1452]

Re: 95 70hp force bucking over 2000 rpms

Thanks roscoe drained the lower unit and the oil looked like gray puddy. so im thinking something is messed up bad . droped the lower unit but can't get the prop shaft to slide out to see if its bad inside there. does the prop shaft slide out easy or do you have to beat on it tried to get a book for this motor today but no one has them so kinda stuck now don't want to brake something thats why im asking if prop shaft slides out or is hard to get out.thanks for any help

 

[roscoe]

Re: 95 70hp force bucking over 2000 rpms

Gonna need a gear puller to get the bearing carrier out, then the shaft should come out.

 

[luvsfishing]

Re: 95 70hp force bucking over 2000 rpms

If you can't find a service manual at a store, try the public library. I found one there and it was a big help for me. My library here had both the Clymer and the Seloc manuals on the shelf.

 

[speeddemon1452]

Re: 95 70hp force bucking over 2000 rpms

Thanks Roscoe and luvsfishing have to go get a gear puller one i have is too short. I will swing by the library see if they have the manual.

 

[speeddemon1452]

Re: 95 70hp force bucking over 2000 rpms

well found the manual but have trouble finding a puller that will fit inside the hub to pull it apart done bourght 2 and returned them as they would not fit inside the hub to pull it off will try sears tomarow anyone know were i can find one somewere else that will work a reply would be nice well thanks

 

[speeddemon1452]

Re: 95 70hp force bucking over 2000 rpms

well have to get rebult lower unit pinion gear was fryed so ordered a rebuilt one should be in soon,learned alot wish i known more about boat eng so i would have found this before i bought it but now i know so won't get a boat without checking into everything before buying it.

 

[eurolarva]

Re: 95 70hp force bucking over 2000 rpms

Have you got your manual yet? Seems to me a new pinion gear needs to be shimmed. Not sure on this, however if it does you will need a manual to do it correctly.

 

[speeddemon1452]

Re: 95 70hp force bucking over 2000 rpms

yes got manual.with all the heat damage to the main driveshaft i am getting a rebuilt unit so i can just put it back together and be done with it bought boat used and the gear lube in the lower unit was thick as toothpaste and gray in color guess they never changed the gear lube in it sence they bought it. so i fig best way to go is to just get a all together rebuilt lowerunit becouse i would have to get all the parts and rebuild it myself would cost almost as much and no waranty. and this way will be fixed faster just have to wait for the hole lowerunit and put it back on and ajust shift linkage and were back on the water. thanks eurolarva will post how it works out wene I get it together.

 

[speeddemon1452]

Re: 95 70hp force bucking over 2000 rpms

well got lower unit and is running good . but i replaced prop with same size one as on the stamp of the old one.10 1/2 pich 13.wot rpms are now at 4200.should be 4750to 5250.old prop did get to 5100 rpms but prop was in bad shape and got desroyed taking it off as it was really stuck bad on there.eng is running good wene i trimed it up at wot tell prop cav rpms jumped up over 5000 soon as i lowered it back at wot rpms droped off to 4200 again.old prop must have been stamped wrong or something.and boy does it use up gas now used over 9gals in a hour and that was at about 3500 rmps never used gas like this with old prop.so should i change prop out again?worried it will break something else allready spent alot on this so any help would be nice.<br />thanks.<br />oh its on a 70hp 1995 force on a 20 foot pontoon.

 

[roscoe]

Re: 95 70hp force bucking over 2000 rpms

Yes, I think you need to drop the pitch on your prop.<br />Look for a 10 or 11 pitch.<br /><br />Are you sure everything is ok with the motor?<br />Doesn't seem right that it is running at mid throttle and using that much gas. That is more than 2.5x what mine uses.<br /><br />I would through a $12 fuel pump rebuild kit into it. When they start to go bad, they leak fuel into the block and it just gets dumped into the lake.<br /><br />If that doesn't help the gas situation, I would think there is something wrong with the fuel recirculation system/puddle valve.

 

[speeddemon1452]

Re: 95 70hp force bucking over 2000 rpms

yes motor was just checked out at local marina here and they said everything was good checked ignition and compresion.and checked all linkage for waranty on rebult lower unit.so might be that new prop i got is overworking the motor and making it drink up the gas .