New Owner Issues

[firstimeowner]

Hello all, thank you for taking the time to assist me.<br /><br />I recently aquired a 1988 Sunbird Corsair open bow (I believe) with a 2.3 OMC Cobra outdrive and motor. It is using a SS 13.3875 17inch prop.<br /><br />I have two issues, hopefully they are related in nature as to not post too many questions on one post.<br /><br />1.The boat itself will run really nicely with 2-3 average size people aboard crusing at 20mph max. If I add anymore the boat will bog down and barely reach 11mph. I believe this is the design limitation of the boat as it rating is 6 people or 900 lbs, with gear 1200lbs. Anything over around 500 and I experience this problem.<br /><br />2. With only one person aboard the throttle and rpm's stop at 3/4, 3800 respectively. After this 3/4 postiion the engine will bog down and actually slow down in speed and rpm's.. It sounds starved or flooded, not sure how to tell. I have read in other posts that the rpms should be hovering around 5000 at WOT, which seems like it would if it weren't bogging down on me..<br /><br />I have never had it stall or die on me while in any thottle position however. <br /><br />I do have some mechanincal (auto) knowledge but have no clue on this.<br /><br />Thanks Again for any advice or input.<br /><br />Kevin

 

[Mahoney]

Re: New Owner Issues

First off, I think 5000 RPM is going to be little high for your WOT RPM, I think you are more in the 4500-4800 RPM range, check to be sure.<br /><br />Your performance even with that little engine seems way off, you should definitely be getting better performance. Trim tabs would help if you dont have them, but that would just be covering up the issue.<br /><br />I had a problem a while back with RPM's decreasing at almost the same point yours are, and it turned out to be a carb problem.<br /><br />If it is not backfiring through the carb and just bogging down, first thing I would check would be the plugs. Pull them all out one at a time and see what they look like. If they are all black and sooty, maybe even wet and smell like gas, I am guessing you are having an issue with too much fuel at WOT. If 4 of them look fine and one looks wet, check to make sure that plug is actually firing with a timeing light.<br /><br />As long as you have the timing light out, check your Advance timing. that could contribute to the engine running (ok) at up to ~2500 rpm or so then starve for power above that.

 

[firstimeowner]

Re: New Owner Issues

Mahoney,<br /><br />Thanks for the quick reply.I have the OMC manual coming in the next fews days and I will check on that and the whole new world that I have opened up by buying this boat.. <br /><br />What are you thoughts on the prop I am using, could this be a problem, the only other that came with the boat is a 13-1/4 x 17<br /><br />I will let you know how it turns out.. <br /><br />Thanks Again

 

[firstimeowner]

Re: New Owner Issues

Ok, I got the manual and it does state that the 2.3 WOT range is 5200-5600 so I know for a fact that since i get no more than 3800 there is a fuel issue, at least it would appear. <br /><br />Also on the trim tabs, (I just learned tonight what they were for from Bennett) I do not have them.. They are a bit pricy for me at the moment but seem to be very helpful. <br /><br />At this point I think I dig into the fuel delivery system, line filters etc and see what I come up with. We have a couple of months of summer left, hopefully I can get her up and running fine before that, then its time to winterize... ugghhh..<br /><br />P.S The plugs were new a week before I got her.. so thats ok..

 

[Don S]

Re: New Owner Issues

So, what size boat is it?<br />While you could have a prop problem, there are lots of things that will keep a boat from running to full rpms.<br />Air leaks in the fuel system between the fuel pump and the tank, plugged fittings in the tank pickup and antisiphon valve, low fuel pump pressure, plugged filter in carb, low compression in the engine, vacuum leaks, timing problems, throttle linkage not opening carb all the way, timing advance not working properly, wrong drive gear ratios is another problem people have found on older boats where the previous owner just stuck any ole drive on there to sell the boat.

 

[firstimeowner]

Re: New Owner Issues

The Sunbird Corsair is 17' in length with 7' 2" beam. It is of the V-Hull design with an open bow walk thru windshield.<br /><br />NOTE: I wish to do it right the first time no matter how much time it takes<br /><br />Thanks

 

[firstimeowner]

Re: New Owner Issues

The Sunbird Corsair is 17' in length with 7' 2" beam. It is of the V-Hull design with an open bow walk thru windshield.<br /><br />NOTE: I wish to do it right the first time no matter how much time it takes<br /><br />Thanks