Questions for the Experts (Walleyehed, Dhadley,...)

[keith8496]

I have a 1984 Evinrude 235 on a 17' tri-hull ski boat. 14.25 x 23' ss prop. One powerpack has been replaced, and the timing has been set by the shop.<br /><br />Engine maxes out a 5000rpm. Speedometer reports 55mph. I am concerned that 5000rpm is too low.<br /><br />Engine runs good w/o load. Engine dies trying to pull up skier. Engines dies pushing boat onto trailer.<br /><br />My local mechanic has given up. I'm on my own!<br /><br />1) the fuel filter won't stay full (boat losing prime? air in fuel?). The motor-side of the filter says full, the tank side emptys in a hurry. I have tested the lines all the way to the primer bulb, all good. The bulb is new and installed by shop. VRO has been disabled, oil-inlet plugged. This is my biggest concern.<br /><br />2) is the prop to steep? The boat obviously planes faster and reaches a faster speed with fewer people, but the motor always reaches the same rpm.<br /><br />3) some water is leaking under the left-side motor mount. Should i look for an exhaust leak?<br /><br />4) cavitation plate is about even with bottom of boat. motor will vent in sharp turns.

 

[Dhadley]

Re: Questions for the Experts (Walleyehed, Dhadley,...)

Is this a 235 or a 2.6 XP? Are the carbs the right one for whichever model you have? Look at the carb abd see what venturi size is cast in (1 1/4, 1 5/16, 1 3/8 etc)<br /><br />Yes, I would think a 23 is a bit much for a low mounted V6 crossflow thats trying to pull skiiers. Yes, 5000 is too low unloaded and really "overpropped" (horrible description - but thats whats a common description) for pulling a skiier.<br /><br />What filter are you looking at that wont stay full? Does the motor quit while under power or are you just concerned about the filter not being full?<br /><br />Upper or lower motor mount?

 

[keith8496]

Re: Questions for the Experts (Walleyehed, Dhadley,...)

To my knowledge it as a 235, not a 2.6xp. The model number is 235TLCRC.<br /><br />The inscription on the carbs read's 1 3/8.<br /><br />The main fuel filter before the fuel pump does not stay full.<br /><br />The motor has a decent hole shot w/o a skier. The motor will die with a skier. The motor will die trying to push the boat onto the trailer. (I don't like floating on...)<br /><br />I just pulled the pulse fitting off the fuel pump. Should it work like a check valve, only letting air flow one way? I can blow through it both ways.

 

[Dhadley]

Re: Questions for the Experts (Walleyehed, Dhadley,...)

Ok, that is a standard 235. Now, with that big carb the initial holeshot will be less than the holeshot with say, an 1 5/16" carb. In fact I'm not sure that the carbs you have dont belong on the XP/GT. Its all a matter of air flow. With big carbs you flow more air at wot but it takes longer to generate the flow to max velocity. The smaller the venturi the quicker it generates max velocity. But its less at wot. <br /><br />Nothing unusual here. With big carbs on any motor it may "passout" when under a real heavy load like a skiier or especially going on a trailer. remember, when you go on the trailer theres a lot of resistance AND the back of the boat (motor) goes deeper in the water. More backpressure.<br /><br />We can do several things to help the overall running. I'd start by playing with set up. Sounds like the prop you have is getting worn pretty bad. Mounted that low it shouldnt vent in a hard turn. The cup out at the tip is probably gone or nearly gone. <br /><br />Another thing to keep in mind is 2 props. One with less pitch that allows the motor to develop rpm quicker for skiing and the other for your top end deal. I'd suggest we get the 23 looked at. If it is indeed worn maybe we can get it rebuilt. Get the cup back in the tip. Then play with the set up to get it as efficient as possible. Then if we need a better prop specifically for skiing, we can look at that.

 

[keith8496]

Re: Questions for the Experts (Walleyehed, Dhadley,...)

I'm already taking the prop to the shop on Monday. I talked to a local mechanic who owns a 235. He had vent holes drilled in the sides of his prop. The said the difference was "night and day." The prop guy only wants $10 for the job. He also said to consider a 21" prop.<br /><br />I have read numorous posts about top end. I read a two page post in which walleyhed explained why it is so important to have your motor running at top RPM:<br /> <br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=28;t=032731;p=1 <br /><br />Can i asume that you arn't that concerned about the air in the filter housing. I can see bubbles being sucked out of the housing to the motor. I was told that causes problems.<br /><br />I also want to thank you from the bottom of my heart for your help. I read lots, and lots of theses message boards. You guys give a lot of your time to people like me. Thank You.

 

[keith8496]

Re: Questions for the Experts (Walleyehed, Dhadley,...)

Also: I placed each of my hands over the thermostats. One side was noticably hotter than the other. Neither side was too hot to hold for 3 seconds.<br /><br />What about the pulse fitting?

 

[walleyehed]

Re: Questions for the Experts (Walleyehed, Dhadley,...)

Your Topic title should read "For the Experts-Dhadley......<br />DH is top man here...<br />Anyway, you talk of a fuel filter and I would venture to guess it's an in-line type??? in-line filters will not "fill" completely.<br />Temp of heads/cylinders will vary at Idle as they tend to cycle up-down at different rates and times. If you check them at around 1200 RPM, they should both be real close and shouldn't get hot enough to have to remove your hands.<br />On the pulse fitting, I assume you are blowing/sucking on the end attached to the crankcase??? The fuel pump works by "pulses" of vacume, then pressure..back and forth just like your heart. This is what makes the diaphram work.