Engine Bogging Down

[Bill Hamilton]

I have a 2002 Nitro 896 with a Mercury 200HP carbureted engine. I have noticed over the past few months that the engine periodically "bogs down" when I try to get on plane. When I say "bog down" I mean the engine is still running but there is no torque and the RPMs stay at the same level. I generally back off the throttle and try again. Most times it goes back to running normal and jumps on plane and I don't have any problem for a while. It idles rough and stalls many times unless I have it in gear and moving slightly.



OK - Thought maybe it was starving for fuel and I had a bad fuel filter. Replaced it. Still no better. OK - Maybe plugs are bad. Checked them and they looked fine and still gapped at .040 like the book calls for. Even though I didn't want to spend the $80 bucks on new plugs I bit the bullet and changed the plugs. Still no better.



Some of the other things I have checked to no avail. Primer bulb in good, stays firm (wish I could say that about myself - LOL). No crimping in the fuel lines. Fresh fuel with stabilizer each tank full.



My thoughts, for what they are worth. Unfortunately, all gas in the local area has 10% ethanol and this may be a factor but I am not really sure. My thoughts are really with a bad diaphram in the fuel pump (mechanical) or the carburetors need to be rebuilt. They have NEVER had any work done on them in six years. Engine may have 100 hours on it in six years (remember I fish the hot side of Lake Anna almost exclusively and stay on the troller most of the time). Run and Gun on the hot side takes 5 minutes, tops!



Any other thoughts and comments about what I can look at as possible issues or fixes would be appreciated. Am certainly willing to take to my local dealer but like to do most routine maintenance myself so I can spend the money on fishing equipment!

 

[Mebassn]

Might want to rebuild your fuel pump... it's fairly cheap and takes about an hour tops.

 

[KEVIN WERHAN]

My guess is either fuel pump or clogged carbs. The ethanol in gas does nasty stuff to carbs, especially if it is sitting for a while. I personally do not put any gas that contains any amount of ethanol, in any of my toys. Cars and trucks, sure, toys, no.

 

[Bruce Freeman]

Switch over to high test and hope that fixes the problem. Corn is killing anything 2 stroke.

BF

 

[Scott Hammer TOXIC]

I wouldn't recommend high test. I run E-10 all the time and don't have a problem. I would replace the bulb just to be sure. I would also run a shock of seafoam. I run Merc fuel treatment in every other tank and at the recommended dosage. I wouldn't tackle anything with the carbs or fuel pump but that is just me. Could be the stator/power pack also but that is a dealer trip also.



TOXIC

 

[mike chip]

bill,

i think toxic is on point this time, i would second everything he suggested.

dont use high test, it has a different burn rate and is much hotter, which equates to bad for engine.





p.s. bill, from everything im hearing the shelf life for ethanol fuel is about 90 days, then it starts to separate and you wont be able to blend it back together, how old is your fuel?

mike c

 

[TOMMY RICH]

Usually if it's a power pack, it won't get above a certain RPM and stay there no matter how much you back off and throttle.

I'd check the bulb like Tox said and then the carbs and pump.

 

[Jim in VA]

Bill - I agree with the others have said. Sounds more like a fuel delivery issue. Run the Seafoam/Techron or other fuel/carb cleaner to see if that helps. It may take a few tankfuls with gradual improvements over time if its gumming in the carbs. Go to the cold side and run up and down a bit (more room to run!).



From your symptoms, sounds like you have some obstruction limiting fuel somewhere along the feed. I'd recommend starting with the easy stuff. Change the bulb (I have a spare if you need to check that out). Pull the fuel line pick up and see if anything got clogged in there (my deck boat had that problem with crap in the pick up causing problems similar to what you describe). Basically, check all that stuff first before tearing into carbs. Good luck.



Jim

 

[Brian Ingersoll]

The first description matches a problem with the fuel pump, but if you're having problems idling also, then it is a carb problem. Do you drain/run the fuel out of the carbs before storing the boat for more than a couple weeks? You can try some of the fuel added cleaners, but nothing beats a good carb disassemble and cleaning. If you do the carbs, I would also do the fuel pump assuming it is the kind you just replace the diaphragms in.

 

[Dan J.]

Everything recomended above is what I'd check. However, don't go changing your octane to other than what is recomended for your powerhead. (87 in your case) The octane rating goes hand in hand with the compression stroke rating of your engine. Higher octane gas will compress more before igniting. (less pinging/knocking)



Higher octane gas DOES NOT burn hotter than lower octane blends.



Higher octane fuels should be used in engines that have higher compression ratings. Use what the mfr. recomends or beware. A bottle of Merc Quickleen is wher I'd start with your conditions. Good luck!

 

[Dewey Storie]

Bill, I had the same problem, I bite the bullet after changing the plugs and took it in to BPS. They found that my carbs were out of sync

 

[Carlos Hathcock III]

Bill, get it fixed??