88 ETLG 150 Sluggish at WOT

[88skeeter]

Hello. I'm new here, but I am hoping someone can help me out. I took my Skeeter out last week during my week long vacation. It had about a half tank of several month old fuel in it. I dumped a can of Sea-Foam in it and topped it off with no alcohol 91 octane at the local gas station. I also treat every bit of gas with Sta-Bil Marine Ethanol treatment. I hit the water and it ran great all morning. I *****ed quite a bit at around 600 RPM with it and also ran it out since the lake was smooth just to run it around due to it sitting the past several months. That afternoon, I went to head back to the dock around noon and it would only rev to 2000 RPM and wouldn't get up on plane. I had my cousin sit up front and could get it on plane that way then trim up and it would slowly gain RPM, but it was really doggy compared to what it usually is. I took the cover off when I got it on the trailer. The plugs are oily, black, and wet. I put a brand new set of NGK's in it. I also noticed the 90 degree fuel line going into the lower fuel pump had a pin hole in it. I assumed it was losing fuel there and didn't have enough to feed it under a load. I changed that too, and it has made no difference. It seems to run okay at idle to mid range, it starts as good as ever too. The problem occurs when I go 3/4 to WOT, it just seems like it has no power. My brother was riding with me on the second test and he seems to think it shakes a little at WOT, I don't feel a dead miss, but it could be running a little rougher than normal. My gut tells me that the carbs need cleaned, but the oily plugs make me wonder if something is haywire with the oil pump. The motor will rev out of gear like its brand new. Only when in gear and under load is it sluggish. Seems to smoke more than normal too, hence the plugs looking like they did. The motor is a 1988 Yamaha ETLG. Thanks for any advice!

Adam

[99yam40]

Check the health of motor, compression spark, timing, and fuel pressure/vacuum.
if that is good the deal with carbs/bad fuel.

adding good gas to bad make a lot more bad fuel

[88skeeter]

Do you think it is possible that it could still be bad fuel since I had about 1/2 tank of old fuel, added 1/2 tank of good, then run it to 1/4 tank before it had trouble? One of the guys at work seems to think it could be the stator. I have a service manual for it. I will go through and check the things you recommended. I hope it is just fuel problems and I can get it ironed out. Thanks!

[TownsendsFJR1300]

As stated, GOOD fuel + BAD fuel = BAD FUEL.

Check/replace fuel filters(under cowl) and transom mounted (if equipped).

Drain the tank as much as possible, drain the carbs (drain plug in each float bowl), catch what comes out (for inspection). Prime the bulb to help flush.

You might luck out with fresh fuel.

If not, sounds like crap / varnish in the carbs.. Pull the JETS, inspect/clean.

[88skeeter]

Thank you. I will give that a try. Will the bad fuel cause the lack of power under a load but run fine otherwise? Also, is the oily black plugs a sign of overoiling, or is it due to the bad fuel not burning properly?

[TownsendsFJR1300]

Thank you. I will give that a try. Will the bad fuel cause the lack of power under a load but run fine otherwise? ABSOLUTELY. DIRTY CARBS WILL OFTEN, IN NEUTRAL, REV ALL THE WAY UP HOWEVER, ONCE UNDER LOAD, (IN GEAR, WOT) ISSUES ARISE-VERY COMMON

Also, is the oily black plugs a sign of overoiling, or is it due to the bad fuel not burning properly?

Doubt it's over oiling, the engines running crappy, (not at 100%), I'd expect to see crappy plugs...

You can also hook your engine up to a separate 6 gallon tank (by pass the built in) with fresh fuel. You'd quickly rule if it's just the fuel in the tank or ALSO the carbs crapped up.

You don't want to clean carbs, then introduce crappy fuel into them-Can you say "do over!"

[88skeeter]

I appreciate your input. I will try and get that all figured out and let you know how it turns out. Thanks again!