Premium gas for '02 Yamaha 115 pump???

overfitty · 03-07-2006, 09:04 AM

Here's my dilemna...just put a used 35 gal tank in my sled last month, hooked to my 4 stroke Yamaha. Filled the tank with regular from Costco...but now it loses power (intermittent) every now and then (NOT good in 6" water!). The mechanic where I bought it checked it out...can't find anything wrong (it won't DO IT for him!), and says it's probably just bad gas. I've got a bout 1/4 tank left, just wondering if I should refill the tank with PREMIUM to up-grade the remaining gas?? What's your thoughts?? Thanks!

Herring Problem · 03-07-2006, 11:07 AM

Why not siphon out the remaining gas, put some in a glass jar to look for any materials that may come out. This will verify dirty tank. If you have a lot a crap in the gas then the fuel filter on the motor needs cleaning. And the gas line pickup tube inside the tank need to be removed and cleaned. Hopefully the carb hasn't sucked a lot of junk into the jets which would plug them.

If gas is clear, check filter, clean , fill tank with a couple of gallons of fresh gas. Run engine to see if its running better.Hope this helps!

fishingls · 03-07-2006, 07:34 PM

Do you have an inline filter? Check it, many times an intermittant problem is the result of a plugged filter.

overfitty · 03-08-2006, 10:32 AM

I'm going to siphon out the old gas this weekend as mentioned above, and check it. Thanks for the suggestions. Will it hurt the engine to run 'premium' gas in it, though?? What kind of gas does everyone put in their 4 strokes??? What brand?? (76...Chevron...??)

KingFisher85 · 03-08-2006, 10:24 PM

Costco
Thats your first problem...
Don't cheat your boat by buying crappy gas...
Should not have to run premium gas but don't buy garbage gas like costco, AMPM, arco....

1pump · 03-08-2006, 11:05 PM

You might check the vent to make sure it's not plugged. Also, you said you put the tank in last month. Last month was ethanol season (depending on where you live) although some stations use ethanol blends year-round. If it was a used tank, the ethanol will knock any crud buildup in the tank loose and send it down the fuel line.
Premium won't do you any good unless you have a detonation/timing issue or high compression.

AM/PM (BP) gas is sub-grade crap and always has ethanol. Costco is unbranded and could come from anywhere. As a rule, unbranded stations buy whatever is cheapest that particular day. Nothing wrong with it, it's just that they're not tied in to a certain brand, like Chevron, Shell, etc.

overfitty · 03-13-2006, 10:24 AM

Thanks for all the info, guys...I removed the remaining old gas, replaced it with 10 fresh gallons of Chevron, and it ran up and down the lower Sandy all day Saturday and never 'sputtered' once!

MattPark · 03-13-2006, 10:35 AM

Premium fuel only has higher resistance to detonation. The only reasons to put it in would be if you heard it pinging, or if the manufacturer recommended it.

ET · 03-13-2006, 11:12 AM

I've worked with a few refineries and you're mistaken if you think just because you go to a "Chevron" gas station that you're always getting gas from a "Chevron" refinery.

Maybe you are, maybe you aren't. You never know. The refineries trade gas when they need to cover shortages due to production or maintenance delays. The only thing that makes a brand-name gas special is the additives that are added to the tanker just before it heads down the road to the gas station. Sit outside a refinery for a while and watch the different tankers roll out. Any brand loyalty you have will quickly evaporate.

I would agree that it is a good idea to avoid AM/PM or any other station that adds ethanol. The ethanol in gasoline does not store well and is meant to be burned up quickly. Keeping it for months in a boat is begging for trouble. The problem described here could very likely be due to old gas with ethanol remaining in the old tank. I doubt the problem was due to the new Costco gas.

Costco gas is far from inferior. They don't add ethanol and they use top grade additives. Per a refinery chemist I know, Costco purchases their additives from a top rated company. The same chemist also said the AM/PM additives used are the cheapest available.

I've used Costco gas almost exclusively in my cars and boat for nearly 10 years now. 245,000 miles on one vehicle and 130,000 on another with zero fuel issues. One big advantage Costco has is that all of their stations are relatively new which means new tanks, new lines, new filling nozzles, etc. They also maintain their filters very religiously. I like my chances at Costco.

namu mac · 03-13-2006, 06:23 PM

All gas in the PDX metro area from 11/1 until I think 3/1 is oxyginated meaning that ehtanol has been added in a 10% blend. This is at all retail outlets by Govt. regs.

MattPark · 03-13-2006, 07:52 PM

The past few years, I don't think the air quality has been poor enough in Portland to require the oxygenated fuels. The gas pumps should all say whether or not the fuel is oxygenated.