[mancem]

I own a 1995 Talari 7.4 BravoIII that has been giving me intermediate acceleration problems for approximately 3years. When I hit the accelerator I get a hestitation that last a few seconds then the boat runs normal. I have had a tune with new wires, plugs, cap, and my carb gone thru by my mechanic who states that he thinks it might be a vapor leak. I think it started when the ethanol was added to the gas and am wondering if anyone has had the same problem? I am looking for any suggestions that I have not thought of.

Thanks
Mancem

[rooperdan]

If your engine is carburated it could be your acceleration pump at your carb.

[mancem]

thanks the carb has been checked and is operating properly

[Zackattack]

I feel the ethonal is a bigger problem than people realize. I am on my first tank of ethenal free fuel now. Have not yet ran it, but all the marinas here are now refusing the ethanol and will be serving up ethanol free fuel.

Find a source, and try it. Thats what I have decided. And change the filter.

[Slash9point5]

Sta-bil makes a marine version that claims to have a method to prevent against the effects of ethanol addative in fuels.

I have used it for the past year and a half of boating and have not had any issues using mostly 89 octane but occasionally 87 octane (both containing 10% ethanol).

Here is a seller on amazon that also lists some info about the problem and its protection method, but I picked up the 32oz bottle for $19.99 at Gander Mountain. The 32oz bottle is a much better deal.

Amazon.com: STA-BIL 22239 Marine Fuel Stabilizer - 8 Fl oz.: Automotive

I'll probably continue to use this product unless I experience fuel related problems as it is roughly $0.06/gallon extra compared to $0.15 to $0.20 extra for non-oxygenated. So, it is saving about $60 gross and $40 net per 32oz bottle (320 gallons of treatment).

Kris

[Shabah 198SE]

mancem,

I agree with rooperdan. It sounds like a fuel/accelerator pump problem. Just because the carb was done doesn't mean that it was set up correctly.

Shabah 198SE

[SEMIJim]

Originally Posted by mancem

thanks the carb has been checked and is operating properly

Regardless of what you've been told: Your symptoms fit perfectly those of an accelerator pump problem. If you don't know what to look for in the carburetor, yourself, I suggest getting a second opinion from a qualified mechanic.

As I've noted many times before here: When you first open the throttle on a carbureted engine, more air starts flowing faster than more fuel, so the engine leans-out badly. This results in hesitation, or even stalling. The accelerator pump is something that's activated when the accelerator is depressed, and squirts an off-setting amount of fuel into the carb throats. Accelerator pumps wear out.

There is one other possibility--I think. But, not being familiar with your engine, I wouldn't begin to know where you should look. That other possibility is a malfunction in the automatic spark advance/retard mechanism/system. See here: Popular Mechanics - Google Books for a description on how they (used to?) work and what they do.

Good luck,
Jim

[KeepitReal]

I had a similar problem with my 4.3 that turned out to be ignition timing out of adjustment. Momentary sputtering and hesitation on acceleration before it would pick up and go. I think my case was somewhat extreme. My timing had been set at 2 degrees ATDC when it should have been 8 degrees BTDC. Adjusted the timing and she ran like a beast

[DFZ272]

Quick accelerator pump test. After engine has been started once and the carb is full of fuel. Turn off the motor, remove the flame arrestor on top of the engine. Look inside the front throat of the carb(U made need a flashlight), then have a friend quickly advance the throttle a couple of times while u observe, if the pump is working you should see and hear fuel squirt into the front throat of the carb. If it doesn't the pump is bad. NOTE: U must be sure the carb is full of fuel for this test to work and don't do it too many times or u will flood the engine.

Hope this helps

Dan

[Dredd]

Originally Posted by KeepitReal

I had a similar problem with my 4.3 that turned out to be ignition timing out of adjustment. Momentary sputtering and hesitation on acceleration before it would pick up and go. I think my case was somewhat extreme. My timing had been set at 2 degrees ATDC when it should have been 8 degrees BTDC. Adjusted the timing and she ran like a beast

Good suggestion.
I worked on a boat last Spring that had an issue similar to this. I could adjust the carb and move the dead spot up or down in the RPM range but never could get it to go clear away, especially under a load. A timing adjustment finally fixed it up right.