ponddipper

Ok...here we go.

I have had problems with my boat from day one. I have a 50" Bonzi, BZx4, WT257. From day 1, after about two-three laps the motor warms up and starts running nice and clean. After @ 3-4 minutes the motor starts rhythmically cutting out, just like I am blipping the throttle every 3-4seconds. At first it is only a stumble, then it gets progressively worse and after about a minute the motor quits.

I have done the following...

Opening and closing H and L needles, all settings to no avail.
Used 87, 89, 92 octane...20/1 ratio and 25/1 ratio mix.
Took apart carb, cleaned fuel filter screen(s) and rebuilt carb.
Bought a new carb.
Rebuilt water pump, bought new water pump.
Replaced all fuel lines, all water lines.
Replaced all gaskets.
Replaced gas cap with BONZĂŤ Aluminum Billet Gas Cap.
Replaced fail safe, then receiver, then crystals, then entire radio system.
Replaced foam insulation around receiver and battery.
Replaced Battery.
Replaced spark plug and am using NGK CMR 7H Spark Plug.

The only thing I think I have left is the flywheel and possibly water in my fuel. I have tried several different batches of fuel though and I keep getting the same problem. So I ask, could my carb be sucking in water and if so, why isnt anyone elses similar setups doing the same? Could I have gotten a little bit of water in my tank and it not have gotten all of it out even after draining my tanks? Does this even sound like water in my fuel? I figure if I had water in my fuel, wouldnt I see the blimping of the throttle right away? Or if its is the flywheel rubbing against the coil, wouldn't I get the cutting out right away and not after 5 minutes of fine running? What about Ethenol mix. I am running 10% Ethenol, not by choice. No one seems to be having this problem with the ethenol fuel mix but I cant help but wonder if it has something to do with it. Could the Ethenol mess up my carb diaphrams after just one run, at 10%? What about the fuel tank, my gas cap lets in and lets out air. Bonzi said it was normal and others seem not to have problems with the gas cap but I read that an improperly vented gas tank can cause these symptoms. How can i tell if my tank is venting properly?

AAARRGGHH! I want my boat to run sooooo bad. Please help me!

Please help,

PD

mmurray70

Seems like you pretty much eliminated all the fuel related stuff. Try an new coil...

Dan S

wow,
you pretty much rebuilt the whole thing.

I'm thinking the same thing here that maybe one of the coils is bad. When the coil is cold it runs good but once the coil warms up it starts cutting out.

The thing is, I don't really like telling you to go buy a red a Grey coil just to see if it will solve the problem, yes you will have a spare coil if its not the problem but its kinds of get expensive to trouble shoot that way.

thanks for the $100 bucks offer but help is free.

Dan.

ponddipper

Thank you for the suggestions. Which coil would be bad? The red, the grey, or both? Would a coil be bad in a brand new boat? This is an issue i have had from the very first run.

Going back to my original questions...would water in my fuel cause the same symptoms of the throttle blipping after a few laps or would it start right away? The blipping only starts after the engine warms up and a few minutes of running has gone by.

Another person suggested that I may have over heated the engine during the break in, (first run) and I now may have compression problems. How serious would that be? Would just replacing the piston ring solve a possible compression problem and how hard is it to take apart the engine and replace the piston ring? I am a novice at these gas boats and engines, would i be able to do this? Thank you to all for yoru input.

PD

mauian

Call Bonzi , telll him the problem , he will know what to do and might be able to solve the problem real quick. He most likely will ask you to send him the motor if its brand new. You might have cooling issues also.

juicr

There is one thing you did not check and i am willing to bet it's the carb isolater block. They get warped and suck air into the cylinder. Remove and set on a flat surface to see if it is indeed warped.

Canadian LoCo

Ethanol Fuel Background: this may also apply to Rc marine gas engines.


E10, Is a gasoline blended with up to 10 % ethanol alcohol and is now in widespread use in the U.S. Ethanol, ethyl alcohol, is made from corn, sugar and other grains.


Alcohol is an excellent cleaner, solvent, anti-freeze and most important, ethanol is hygroscopic, meaning it will absorb large amounts of water.


Government regulations and laws for ethanol fuel use and labeling differ from state-to-state, and are constantly changing. View Ethanol Handbook 2006 State-By-State Laws.


The most serious boat engine problems, resulting from ethanol E10 use, have mainly occurred due to illegal amounts of ethanol (over 10 %) being incorrectly added at the gas station pumps, by the delivery truck drivers..


Since using over 10 % alcohol gas is dangerous, it will invalidate all marine company engine warranties.


Many ethanol problems, reported by boaters appears to be due to their lack of knowledge/information on how to properly manage alcohol fuels.


Many boat engine breakdowns in recent months are directly related to the mismanagement of E10 gas.
Your marine mechanic may not even suspect or test the fuel as a possible cause of breakdowns. Many marine engine repair businesses have flourished as a result of ethanol gas engine damage.


Several older engines can not use any fuels that contains alcohol. Eg. Certain fiberglass tanks, mostly manufactured prior to 1992, will decompose from alcohol.


Fortunately newer outboard engines (past 5 years) have been designed to be more compatible with alcohol fuels.




Reasons Boat Engines Have More Problems with Ethanol Gas:


Boaters, often store gas in tanks longer than recommended for E10 (90 days).
Cars, unlike boats, usually replace fuel every week or two, which will successfully prevent the possibility of water-contamination/phase separation.


Boat engines live in a water environment - Alcohol gas loves to absorb water.
Ethanol E10 gas can absorb large amounts of water into the fuel tank, MTBE in conventional gasoline did not.


Plus, boat engines usually last longer than cars. Still owning and using a marine engine from the 1970's or 1980's is not uncommon. * These older engine parts and tanks were not usually designed or tested to withstand the damaging effects of alcohol gas.
* Several older marine engines (made prior to 1992) have plastic and rubber parts, and fiberglass tanks that are NOT compatible with E10 alcohol fuel.