2005 Mercury 90 hp 2 stroke

bcj.jones

Seaman
Joined
Nov 17, 2017
Messages
72
Just recently boat an 18' aluminum bass boat with a 2005 mercury 2 stroke 90 horse. The boat has been sitting for a whole and has some old gasoline in it. It completely plugged up the inline fuel filter. I installed a new clear fuel filter and after priming the pump debris from the fuel tank were already in it. It still will start and run. It'll actually get up to about 40 mph at 5500 rpm. It hardly will idle and definitely struggles and sputters on accelearation. New plugs and good spark.

is running this fuel bad for the motor? Can I harm it with it running so rough on acceleration?

The tank is almost full, should I just run it out or drain it? It' a built in 20 gallon tank, should I clean it somehow?

Thanks for all the help!
 

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,286
Ditch it. More problem than its worth. Fuel restriction gives the danger of running lean too. Never good on a 2 stroke.
Fresh fuel and filter and clear the tank and pick up will see her right.
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,033
Have you confirmed that the oil injection system is in service and working properly ?
 

bcj.jones

Seaman
Joined
Nov 17, 2017
Messages
72
After getting ahold of him he said it's only 6 month old fuel with stabilizer added. Sure didn't look like it though.

Where the heck do I drain 20 gallons of fuel?

Oil injection system is working properly as far as I can tell. Don't they have a fail safe mode or warning if some kind when the do fail? What do yall think of disabling that sysem and just pre mixing the fuel?
 

bcj.jones

Seaman
Joined
Nov 17, 2017
Messages
72
Another questions as well, how good are those inline fuel filters? Meaning, with that much debris coming out of the tank, is it pretty much guaranteed I need to pull and rebuilt the carbs? Or are they generally pretty good about keeping that stuff out?
 

Mercurylips

Petty Officer 2nd Class
Joined
Sep 23, 2015
Messages
189
I use my old fuel in my jeep. Highly diluted but it doesn't go to waste. If it is still good it goes into a gas can for my snowblower which is also 50 to 1. When I had debris in my two tanks I poured it off into a screened funnel and into clean gas cans. You can figure it out.
 

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,286
The oil injection pump itself was pretty reliable on those engines....just usually the lines, fittings and hose that perishes. And they won’t send you an alarm when they fail. Usually no alarm given unless the tank is low or it’s too late. When new you might have got a low feed or filter clogged alarm, if lucky.
I would buy a manual pump for $10 off eBay and pump it out into Jerry cans and fire it in the car with a bit of fresh fuel added occasionally !
 

wn6ngp

Petty Officer 1st Class
Joined
Aug 12, 2012
Messages
209
I've got the same motor except 2000 year. I had some fuel problems before that required carb clean etc. I replaced fuel lines too. After that experience I drain the fuel out of the tank once it gets 4months old. Usually burn it up in my lawn mower sometimes the car. I would not use the fuel in any other 2 stroke engines like chainsaws etc. Once the fuel gets that old the ethanol has absorbed lots of water which drives the octane down. Ultimately the ethanol/water mixture can separate and that's a big headache.
 
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