Bad Fuel Issues

[NorthWoods]

Hi,

Winter 2004, put engine (2003 Nissan 18hp 4-stroke) away with fuel in the lines and in the carb bowl. Summer 2005 sputtering and losing power. Continues to get worse through the season. Fall 2005, end of season, drain bowl and attempt to remove fuel lines. Very tight construction, and some of my fuel lines are stuck on, so after much tugging, I give up and satisfy myself that draining the bowl is a good start. Spring 2006, chugging and sputtering, can't get over 5mph. Decide to clean carb after asking around. Take carb off and apart- clean as the day it was born. Blow it out with compressed air anyway. Find a break in my fuel line going from fuel pump to carb- from my tugging the previous fall. This was letting air into the system starving the motor of fuel, which was compounding my bad gas issue. Replaced all fuel lines inside engine and drained line going from tank to motor. Also changed gas in 3 gallon tank and checked all filters. Everything back together and after about three minutes of interesting back firing and sputtering, she started up and ran like she had the previous summer, sputtering, but at least planing out. Tuned in the idle adjustment screw until she ran great. I'm finally back on the water after almost an entire year without Mad Russian.

My conclusion, my problems were my fault. I should have stabilized the fuel in the tank at a minimum and ran the engine dry before putting her away for the winter, and opened my bowl to allow everything to air out. I have decided to stabilize all my fuel from now on since I only go through about 9 gallons a season, or 3 fill-ups. That means that the fuel in my 3 gallon tank can sit around for up to a month or more. Many folks say fuel sitting in a tank is only good for a couple weeks. I hope this action will help.

[PAR]

Fuel will not go "bad" in a few weeks, it takes months, but is usually salvageable with a bottle of conditioner/stabilizer. The stabilizer does a pretty good job on varnish too.

[kiwi]

One of my friends runs his 2 stroke dry after each outing - he hooks it up to the garden hose and runs the motor till there is no gas left in the carbureter while rinsing.

I agree that quality fuel should take longer to go bad. If I was lucky enough to have a motor I would probably empty the external gas tank into my car regularly any way.

Tony

[NorthWoods]

Well, I added stabilizer and that will be my new routine. I'll let you know if it works over the long haul. I've been instructed to try SeaFoam too. I'll look into that, but it's a new product to me, so I'll have to read up more on it.

[fishingdan]

Dave,

I agree with you that us recreational boaters should use a fuel stabilizer in every tank. You never know when something comes up and you can easily not use the boat for a couple of months.

I am sold on seafoam since I started using it in the spring. I use it in every tank of fuel now. I have also started to use in my yard equipment (chainsaw, lawn mower, riding mower, etc).

Also check out seafoam's Deep Creep spray. It is excellent.

Dan

[NorthWoods]

Well that's a good enough endorsement for me. Thanks Dan, I'll try it.

[NorthWoods]

Hi again,

I posted this question at another site too, I need all the help I can get because I'm no mechanic. I've got my motor running fairly well again, as stated, but I'm still getting air into the system somewhere. The bulb gets a little soft after about five minutes of run time. Is this okay, or should I be looking for air leaking in somewhere? Does anyone have a good, tested process for tracking it down? Thanks for any help.

-Dave

[fishingdan]

Not really, but there can only be a few areas to check. I think that you are probably right in that you are getting air in the system.

- I always start at the bulb.
1) Is the bulb oriented the right way? The arrow on the bulb must be point in the direction of the engine AND it must be pointed up. I learned this the hard way on my console skiff. If it is not pointed up, the internal check valve doesn't work well and it loses prime.

2) If you went with a Tempo brand bulb, I would replace it. Many are faulty and the good ones don't last very long. Install an OMC or Mercury OEM bulb. They cost basically the same and, from my experience, they are much better.

- Pump your bulb and watch for leaks. If there are any leaks, they will drip fuel. If they exist, these same links will let air in and you will loose prime. In the past, I have seen problems with the fuel line adapter (connecting the fuel line to the engine);
INSERT INTO phpbb_posts (old_post_id, topic_id, forum_id, poster_id, post_time, poster_ip, post_username, post_subject, post_text, enable_bbcode, enable_smilies, enable_sig) VALUES internal engine fuel lines (under the cowling) and a sticking needle valve on a carb (fuel will drip out of the carb);
INSERT INTO phpbb_posts (old_post_id, topic_id, forum_id, poster_id, post_time, poster_ip, post_username, post_subject, post_text, enable_bbcode, enable_smilies, enable_sig) VALUES of the main fuel lines themselves.

- Possibly a hole in the fuel pump diaghram. Hard to detect, but easy and typically inexpensive to repair.

Hope this helps some.

Dan

[NorthWoods]

I didn't know all that about the bulb orientation, Dan, good to know. The tank, bulb, hose and connectors are all from Nissan, and came with the motor. They are three years old (plus);
INSERT INTO phpbb_posts (old_post_id, topic_id, forum_id, poster_id, post_time, poster_ip, post_username, post_subject, post_text, enable_bbcode, enable_smilies, enable_sig) VALUES and it may be time to upgrade them.

Yes, I heard about a problem with the o-ring in the connection adapter on the motor side. I heard if that o-ring gets even the slightest hairline crack in it, it could let enough air in to cause problems. I'll have to check that too. I replaced all the interior fuel lines from the under cowling fuel filter to the pump and from the pump to the carb. I've got enough line to replace the piece from the connector to the fuel-filter, so I guess I'll do that too.

I guess I'd better buy the carb kit and do a thorough cleaning and reconditioning before I go much further. I'll let you know how my progress is going in a couple weeks.

Thank you for all your help.

[fishingdan]

Good luck with it Dave. I can't imagine with the age of your engine and low hours that you would need to rebuild the carb(s) at this time. That is typically a 10+ year old activity.

You will find that any hair line or pin hole leak in the fuel system will cause problems.

By the way, how is the engine running when the bulb gets a little "squishy"? Is the engine running well? While the engine is running, the bulb will not feel as firm as it does before you start it (after you have pumped it up). Once the engine starts running, it starts to draw fuel and the check valve in the bulb has to open a bit.