88 horizon giving me engine and prop issues.

[s2gots]

I need some help and advice guys..I have a horizon 200 with Cobra out drive, and 5.7 gm engine. I've owned this boat for the past 7 years or so, and it has never given me problems...Ill start from last year, which was the last time I used the boat...
was out a reservoir, where speed limit is 5 mph throughout lake..went out to fish with a buddy. we were close to shore in shallow water. I had to back up for whatever reason, just out of idle, prop spinning, and hit ground. Engine shut off. Didn't think much of it because it fired right up, and the rest of the day seemed to run fine. end of day, pulled it out of the water, and the aluminum 3 blade prop was pretty chewed up.
I bought a new aluminum 4 blade prop. The 3 blade prop is a 15" with 17 pitch. The new 4 blade is 15" with 16 pitch. Installed the prop, all looks good. At the same time, also changed the spark plugs, engine oil, and out drive oil. Fired it up with a hose/earmuffs, all work good. idles fine, oil pressure good, battery volts good. After this, I didn't have a chance to take it out on the water until yesterday, about a years time. ( every month or so, I did hook up the hose and started it up, all seemed good)
Two days prior to yesterday, got the boat up and running,checked all fluids, started it up, all was good, again. Filled it up with gas, about 30 gallons. There was still a bit of gas in the tank since last year.
Get to the ramp, battery was completely dead. Switched it out with my buddy's car battery, which was smaller, but seemed to temporarily work. Once in the water, took a bit of throttling to fire up. got going in the no wake zone and all seemed good. In open water, throttled up, and instantly something didn't feel right. The RPMs would jump up about 800-1000 rpm but the boat seemed to bog down and not speed up. It would do this about every 20 seconds or so. At first thought, was cavitation, with the new prop. Decided to heat back to dock to swap out the new prop, with another prop(not the chewed up one).
At the dock, the engine idle was not right, seemed low and almost like a slight misfire. oil pressure was very low, and so were the volts, they were erratic, down to 10 volts at idle. I gave some throttle, rpms smoothed out, oil pressure went up, and volts went up to 13.5. I shut it down. A few minutes later, went to restart. Engine would crank over good, there was a good smell of fuel(not from leaking fuel) but it would not fire. After 30 minutes, It fired up, but it took allot of throttling, and finally started with WOT. Let it idle for a few minutes, then shut it down, and tried to restart. It started up just fine, though it still didn't seem right while it was idling.
We decided to call it a day, and went to get the trailer. Took about 5 minutes. Boat wouldn't start anymore. We had to push/pull with ropes around other boats to load it up.
I need some advice on where to start my search of this problem...any help will be greatly appreciated!


TIA

 

[Howard Sterndrive]

start with a compression test of the engine

 

[s2gots]

Couple things I noticed today, first, the upper most gasket on the carb was wet, it's obvious a bad gasket..seems maybe a carb rebuild is in order? Second, I put the drive in gear, engine off, and spun the prop by hand. It took some effort, but it did move. It wasn't the bushing, because the spline was turning also. (Outdrive was all the way up) Is this sounding like something major?

 

[Lou C]

It sounds like you might have a couple of different problems...
One, when you hit bottom, that might have damaged something in the drive. If you have someone at the helm to shift the remote control, and spin the prop, when its shifted from neutral to fwd, or rev, it should lock in that gear. If its slipping or ratcheting, thats not good.
Two, that prop is not right for the engine, the pitch is way too low. The V8 models came with a 14.5x19 prop and the V6 models came with a 15x17 prop.
The running issues sound fuel system related, but the ignition system should be checked out as well.

 

[s2gots]

Thanks Lou C for your input...the 15 inch props came with the boat when I bought it, I never had any issues with the 15" props! What can I expect to gain by going to the 14" prop? Thanks!

 

[Lou C]

Its not so much the diameter that's important (this is limited by what size props fit the drive), its the pitch of the prop (the distance the prop would move forward in one revolution in the water, assuming no prop slip). You want the engine to be able to reach its max rpm as specified by the manufacturer, too low and the engine will labor and tend to run hot, too high and the engine can over-rev. If you can get that with a 15 prop its fine, but I know in their (Four Winns) specs for the OMC engines, the V8s of that era had 14.5x19s. BTW, I have the same boat except with a V6. It came from the prev owner with a 14.5x19 and it would not pull max rpm (4600-4800). I put a 15x17 on it and it performed much better.

 

[s2gots]

Ok, so I had some one help me, I was spinning the prop, and they put it in gear. Tried it forward, and reverse. It locked up solidly, no slop or ratcheting sound. Now,I think the best thing to do is have the carb rebuilt, install one of my old props, and head out again....

 

[jerryjerry05]

You do a compression test?

 

[s2gots]

Yes, just did late last night..Here's the results Cyl1- 140 2-150 3,148 4-140 5-130 6-145 7-131 8-138 The numbers may be off a few psi, the gauge had 5psi increments....the boats 26 years old!!....