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No power under load for my 23L Cobra

S

salernoa

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"I have a 1989 Four Winns with

"I have a 1989 Four Winns with a 2.3L (Ford) OMC Cobra. It has run excellent for the 6 years I have owned it, pulling skiers, tubers, etc.

Last year it developed a 'hiccup' at cruising speed. The engine stumbled for a brief second and then continued. The problem got worse over time so that it was happening every 20 seconds.

While trying to resolve the hiccup I have replaced the spark plugs, plug wires, distributor cap, rotor, points, condenser, fuel/water seperator and coil. Reset the dwell, idle speed and timing.
The boat continued to run poorly.

I took it to a professional mechanic and he swapped the points for another new set and set my timing at 8 BTDC. I had it set to 10 BTDC. The problem wasnt resolved and the boat was noticably sluggish. By the end of last year, the boat began to bogg so bad it would barely plane.

This year I took it out and confirmed the same behavior. I had the carburator rebuilt and still the boat has no power.

I checked the ESA, after spending hours reading through this BB. It seems to be functioning correctly. If in nuetral at 1200 rpm I manually engage the switch, the rpm's are cut way back. If however the boat is in forward gear and turning 3500 RPM, activating the switch has no noticable effect on RPM.

The engine starts easy, idles nice and with no load (in the driveway with the muffs on) will rev up to 5000 RPM with no problems. Put it in the water and it will not accelerate enough to make the boat plane. It wont rev past 3000 RPM and occasionally backfires.

A fellow boater suggested it may be the outdrive (upper bearings seizing)and not the engine. I checked the oil level in the outdrive and it appears normal.

Any ideas what else I could check? How do I verify if it is the outdrive?

Please help, summer is short in Michigan and this one is getting away from me."
 
"First of all I read a few thi

"First of all I read a few things I don't like to see

The engine starts easy, idles nice and with no load (in the driveway with the muffs on) will rev up to 5000 RPM with no problems.
Don't rev it this high, you will damage something, there is not a garden hose around that can give you enough water flow at that RPM

If however the boat is in forward gear and turning 3500 RPM, activating the switch has no noticable effect on RPM.

Don't do this either, kind of dangerous at that speed out on the water. The reason it didn't work for you is because the overstroke switch is engaged when in gear and it effectively opens the Interrupt switch circuit because you don't want the ESA to engage while in gear especially at that rpm.

Based on everything you've done I would go for a compression check."
 
"Check the Voltage Regulator?

"Check the Voltage Regulator? Are your batteries warm to the touch? Mine was doing the same thing, and that was the problem."
 
I havent checked the voltage r

I havent checked the voltage regulator yet but will look into this tomorrow.

Bob...I did perform the compression check tonight. All of the cylinders measured 110 PSI. What next?
 
Make sure that all 4 cyl's

Make sure that all 4 cyl's are actually firing. Easiest way is to have engine idling and pull the plug wires off (1 at a time) and listen for a drop in RPM's.

When the mechanic replaced the points did he also do the condenser? Do you know what the dwell is set at? (should be 34-38 deg).
 
"Might check the centrifugal a

"Might check the centrifugal advance mechanism in the distributer. Could be stuck or broken.

Has the boat been stored under a roof? If not, it could be waterlogged."
 
"Ok, so I checked all the plug

"Ok, so I checked all the plug wires for resistance. They appeared good. I checked for spark at each cylinder and again it appears good.
The dwell checked out at 36.
When I through the timing light on, it showed TDC...(whatda???) so I set it back to 10 BTDC.
I plan to launch the boat after work today and see what I've got.

Chuck: Im wondering if the centrifugal advance mechanism being 'stuck' could cause the timing to change. Is there a way to test this mechanism or do I need to diasassemble the distributer and evaluate?

If the timing isnt the answer i will look into finding the anti-siphon valve.

Thanks for all the help guys."
 
"Anti-syphon valve should be t

"Anti-syphon valve should be the fitting on the tank where the engine fuel supply hose attaches to. Usually a right angled fitting with a barbed end.

Was the distributor loose? The advance mech should not cause your base timing to change like that, it just won't advance with the rpm's like it should. Take the cap off and grab the rotor and give it a twist, you should feel/see the spring tension return it to normal or better yet remove the points plate and look at the weights/springs themselves for broken or rusty ones."
 
So I lanuched the boat last ni

So I lanuched the boat last night and found that I no longer have a bogging problem under acceleration (amazing what the correct timing will do). I still have the 'chugging' at high speed.
I plan to review the counter weights/springs and siphon valve tonight.

No the distributor didnt appear loose.
 
When was the last time you cha

When was the last time you changed your fuel filter? I've had this occur on several occasions over the last 12 years and each time it was because my fuel filter was old and it was restricting the flow. Problem only shows up when you put on the gas.
 
"The fuel filter was changed w

"The fuel filter was changed when I had the carb rebuilt about 2 weeks ago. I changed the fuel seperator about a year ago when I first began experiencing the problem.

I took the distributor out and the springs appear to be in place. I spin it and can hear the weights moving. I can also gently shake the distributor and hear the weights move. Im not sure if that is good or bad? I dropped off the distributor at the local marina and the mechanic is supposed to look at it Monday.

As for the anti-siphon valve, I have that pulled off but Im not sure what to look for? The ball seems to depress easy enough and the spring pushes it back. Is there any other test I should perform.

Thanks again."
 
The mechanic verified that my

The mechanic verified that my distributor's mechanical advace seems to be functioning correctly. The springs are in place and not rusty.
I put the distributor back in and reset the timing. So I have worked for 2 weeks and Im back where I started.
I am planning to test run the boat from an auxillery gas tank to determine if the fuel pick-up or rubber fuel line is causing the problem.

Any other ideas?
 
"Wow, this is a stumper. You&

"Wow, this is a stumper. You've checked your valve lash? Exhaust manifold gasket is sealed? Operating at correct temperature? No water in oil? Pressure tested fuel pump(!)? Could it be that your cam is worn out? This hapened to me but my boat is 35 years old; it was time."
 
"In an effort to further my di

"In an effort to further my diagnostics of the situation I have borrowed a vaccuum gauge and was prepared to hook it up and run a little evaluation but, at the risk of sounding incompetent...where on this motor do i hook up a vaccuum gauge? There is no obvious vaccuum lines or fittings to tap into?"
 
"I have another thing for you

"I have another thing for you to check: open up the carb and remove the float(s) to determine if one (or both) are saturated/filled with fuel. If so, then replace it(them). This may not necessarily be caught in a rebuild.

You probably don't have a vacuum advance; it is likely mechanical or electronic. You can check this with your timing light by setting your timing at low idle and then reving up the RPM and ensure that the timing mark advances as the RPM goes up. It should start to move almost immediately, if not immediately, as you increase the RPM."
 
"Also, what does your manual s

"Also, what does your manual say the correct compression lbs should be? 110 seems low. Are all cylinders registering 110lbs? If not, what are the readings? Did you do a wet test to see if compression goes up (add 2-3 squirts oil into cylinder through spark plug hole and then recheck compression)?"
 
warm the engine up and wire th

warm the engine up and wire the choke open. then disconnet the vacuum line for the choke pulloff. that is the only place I have found to hook up a vacuum guage
 
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