WOT problems on a 35 rude

[Lubosleftboot]

Hi Guys

I have done a search of the site but I cannot find an exact match to my problem so I have decided to start a new thread.

I recently rebuilt my 1981 35 hp rude and it is now fitted to the back of my boat.My problem is that my engine will not go to WOT.I have cleaned the carb throughly and fitted a new carb kit plus the primer bulb has been replaced on my fuel tank.

I have noticed that if I blank off half of the venturi with a piece of tape then the engine goes to WOT no problem and is pushing my boat on to the plane @ around 20 knots.

I have tried moving the mixture needle in and out in small increments but no joy.The funny thing as well is that the motor is fine at low rpm no spitting or missing and the motor is pumping plenty of water so there is no overheating issues...

Is my carb finished?I have a 30 hp Jonny for spares and I was thinking of using the carb off that....Would that work?

All advice is appreciated guys.....

LLB

 

[Harker]

Re: WOT problems on a 35 rude

Did you rebuild the fuel pump too. Make sure all the hoses are tight so no air is getting sucked in at WOT too. Might want to check your float setting also.Is this with the tank of 25:1 break in fuel?

 

[Windykid]

Re: WOT problems on a 35 rude

I assume you meant block off venturie. If this worked then you have a fuel starvation problem.

 

[steelespike]

Re: WOT problems on a 35 rude

You may need to go through the carb again.It sure sounds like a plugged/dirty high speed jet.You need to be sure all demensions are good
and prove all passages are clear.

 

[Windykid]

Re: WOT problems on a 35 rude

Have you tried pumping the bulb while going to WOT?

 

[tashasdaddy]

Re: WOT problems on a 35 rude

i agree with fuel starvation, blocking 1/2 the air makes it run.

 

[Lubosleftboot]

Re: WOT problems on a 35 rude

i agree with fuel starvation, blocking 1/2 the air makes it run.

I have gone out to the boat today and removed the carb as I agree with what you guys are saying in relation to fuel starvation.I will strip the carb down again and double check everything including the float height.

When I removed the carb there was plenty petrol in the bowl as I drained it via the drain plug on the carb base so I assume as the engine runs ok at idle that the main jet must be the culprit.

In my original post of this thread I also asked if I could fit a known good carb from a jonny 30 to the rude without performance being affected?Does anyone know?

Once again thanks to all that replied that is what makes this forum the best boating forum on the net.

LLB

 

[Lubosleftboot]

Re: WOT problems on a 35 rude

Have you tried pumping the bulb while going to WOT?

Yes that made little difference WK



LLB

 

[Lubosleftboot]

Re: WOT problems on a 35 rude

Any advice on the carb swap guys?

 

[Lubosleftboot]

Re: WOT problems on a 35 rude

Bumpty bump.....

 

[Chinewalker]

Re: WOT problems on a 35 rude

The 30hp is likely the later version of the 35. When they started rating the motors at the prop, the 35 became the 30.... So, to answer your question, yes, you can probably use the 30hp carb without a problem...
- Scott

 

[Lubosleftboot]

Re: WOT problems on a 35 rude

The 30hp is likely the later version of the 35. When they started rating the motors at the prop, the 35 became the 30.... So, to answer your question, yes, you can probably use the 30hp carb without a problem...
- Scott

Thanks for the info Scott I will fit the carb tomorrow after work and let you know how it goes buddy



LLB

 

[F_R]

Re: WOT problems on a 35 rude

There is a good chance that the 30 carb has a smaller venturi. Would result in loss of power.

Getting back to the other carb, did you tke out that high speed orfice plug and check it for restriction? Everybody overlooks it because it is buried deep down in the hole behind the hex drain plug. That almost certainly is your problem. ANY gum or coating at all in the orfice will cause lean running which would be overcome by choking as you are doing by blocking off the air flow. Saying again, it needs to be absolutely Clean!!!

BTW, before you even try it, the 30hp orfice plug is probably a different size, so don't swap parts across carbs.

 

[Lubosleftboot]

Re: WOT problems on a 35 rude

There is a good chance that the 30 carb has a smaller venturi. Would result in loss of power.

Getting back to the other carb, did you tke out that high speed orfice plug and check it for restriction? Everybody overlooks it because it is buried deep down in the hole behind the hex drain plug. That almost certainly is your problem. ANY gum or coating at all in the orfice will cause lean running which would be overcome by choking as you are doing by blocking off the air flow. Saying again, it needs to be absolutely Clean!!!

BTW, before you even try it, the 30hp orfice plug is probably a different size, so don't swap parts across carbs.

Thanks for the reply F_R but I have switched the reeds the manifold carb and choke assembly over and today I had my boat up on the plane doing around 20 knots

As Chinewalker posted I reckon the carbs are the same as the output was measured at the crank in the early 80s and at the prop in the late 80s.

My motor is a 1981 but the carb came off a 1989 jonny 30.

The only problem I have had was starting and idling but after a wee bit of perseverance with the main adjusting jet the motor is now going like a rocket

Thanks to Harker,Steelespike,Windykid,Tashasdaddy, imported_F_R and Chinewalker for all the advice you have all been most helpful



LLB