2008 Yamaha 150 2 stroke (150 TXR) issues

[911grizzly]

Low hours, original owner, first use after 8 month layup. Stored properly following all proper procedures, stabilized non-ethanol fuel, etc. The motor is in mint condition, although I have not changed the sparkplugs for a while but probably only 50 hours or so on them. Fuel filter shows fuel is pristine.

At low RPM's (1,000 - 2,000) intermittent engine stumble or misfire. Almost feels like there is a gear missing a tooth in the driveline? Like a hiccup. It feels like an ignition problem. The motor has not died yet, but it seems ominous. I also notice a bit of surging up and down around 2500-3,000 RPM.

[99yam40]

possibly a lean sneeze you are seeing

[cpostis]

There are many opinions on "storage/winterizing procedures".I'm sure you'll hear a few from here.

Do you drain your carbs when you store your engine? I would not doubt if you have some blockages in your idle/low rpm circuits within. IMO, Might want to try running the engine on separate portable tank mixed with "shock treatment" of gasoline and Ring Free. I have had success with other engines that did not quite run right doing this.

Here is an excerpt from a "sticky" Boats.net has posted following with a link to the post:

"On models that have drains on carburetors or vapor separator tanks (EFI Models) loosen drain screw on bottom of carburetor bowl or VST tank and drain all fuel from carburetors or VST. Remove the engine fuel filter and empty the fuel from the filter."

http://www.yamahaoutboardparts.com/f...e-th11622.html

[911grizzly]

Thanks for the replies. I have not drained the carbs before storage, but I have used exclusively ethanol free fuel and fuel preservative before storage. Probably a mistake not to have drained the carbs - I will have to figure out how to do that.

As for running on a portable tank with Ring free, I can try that. I thought Ring free was to protect the piston rings, not a carb cleaner. What about the stuff called Seafoam?

[99yam40]

Fuel left in the carb bowls evaporates and leaves residue behind plugging things up.
mixing stuff into the fuel and running can help, but if one or more cylinders are running lean due to that residue there is a race to see if it will clear it up before the lean running hurts something.

I have seen pistons melt,seize, and rods come out the block winning the race

[cpostis]

Thanks for the replies. I have not drained the carbs before storage, but I have used exclusively ethanol free fuel and fuel preservative before storage. Probably a mistake not to have drained the carbs - I will have to figure out how to do that.

As for running on a portable tank with Ring free, I can try that. I thought Ring free was to protect the piston rings, not a carb cleaner. What about the stuff called Seafoam?

I never used Seafoam, I have no opinion one way or another on this product.

\Ring Free:

"Highly concentrated YamaLube Ring Free PLUS is a proven engine deposit cleaning package. When used as directed, this top-quality deposit-control sytem removes deposits from fuel injectors, carburetors, intake valves, intake ports, and combustion chambers. These harmful deposits, often the result of poor quality gasoline, may cause knocking/pinging, power loss, hesitation, shortened spark plug life, piston ring sticking, and even expensive engine damage. This special fomulation also helps protect electronic parts and fitting in the fuel system against the corrosive effects of sulfur compounds in ethanol (E10) fuels. May be used with Yamalube Fuel Stabalizer & Conditioner PLUS. Improves power and efficiency in two and four stroke engines. Use this product on a continuous basis to provide maximum protection against deposits. 1 oz Ring Free PLUS to every 10 gallons of fresh gasoline."

"Add to fuel in either SHOCK TREATMENT for oil build up or CONSTANT TREATMENT to maintain protection from harmful deposit build up. After SHOCK TREATMENT it is recommended to change oil in 4 stroke engines. Older heavily deposited engines may require a second shock treatment. SHOCK TREATMENT: 2 oz./gal. CONSTANT TREATMENT: 1 oz./10 gals. Minimum SHOCK TREATMENT per engine: 3.3L to 1.7L engines - 64 treated gallons 1.6L to 700cc - 24 treated gallons 699cc and below - 12 treated gallons"

IMO, my recommendation:
I would drain your carb bowls and filter bowl first, shock using a portable tank with a gallon or two gas and the 2oz. per gallon Ring free concentration, pump primer bulb until hard and fuel filter and carb bowls full, run about 10 minutes, let set an hour or two, and re-fire your engine. Hopefully your "low RPM's (1,000 - 2,000) intermittent engine stumble or misfire" will disappear.

Add ring free at the recommended "CONSTANT TREATMENT: 1 oz./10 gals." to your fuel tank, and see if you have improvement to your "surging up and down around 2500-3,000 RPM" problem

Of course this is assuming your problems are related to "dirty carbs" and other components within your fuel system and engine. You could have other problems.

Highly recommended for regular use.

Townsends, others what do you think?

[TownsendsFJR1300]

I think you nailed it Chuck...

As long as there is some fuel getting past the clogged jet, it should help.. And, IME, the RF works best at cleaning the fuel system and keeping it clean.

I'd run it just fast enough where there's NO lean sneeze, etc and the fuel / cleaner gets into all the nooks and crannies...Add RPMs as/if the engine "takes it".

If its completely clogged and doesn't dissolve, you get to pull the float bowls off and check /clean jets.

Some fuel stabiizers work better than others. Draining the carbs (one bolt on the bottom of each float bowl) is best for the end of the season.

Just curious, what brand of stabilizer?

I do use Seafoam mostly for lubing the top end of an engine being stored...

Short story, a friend acquired a Kawasaki 500 twin MC with VERY clogged carbs. Drained them (nasty), tried starting, of course no start. I offered to pull them and clean. Friend didn't want to yank them so we drained the bowls again, then poured straight Seafoam down the fuel line to the carbs. Let is sit for a couple of hours. Later came back, drained and put in new fuel.
Cranked it up. One cylinder "hit", smoked like a b...h, kept revving it, eventually #2 hit... Purred like a kitten and NEVER pulled the carbs.

[911grizzly]

Update: I have not yet had a chance to buy some Ring Free and run it on a portable tank, but I've used the motor a few times since my last post and, if the problem hasn't disappeared entirely, the motor is running better than before.

Here is what happened: I noticed that one of the fuel line connections between the internal fuel tank and the motor did not have any sort of clamp on it. I put on a small stainless steel hose clamp and tightened that up, and the "lean sneeze" or whatever problem it was more or less went away. I'm theorizing that maybe some air was leaking into the fuel line from this unclamped connection.

I need to figure out the best way to clamp these fuel lines. I don't think typical plumbing hose clamps are the best, and the other fuel line connections on this boat are clamped with zip ties (cheesy installation by dealer when repowering). There are at least 7 separate fuel line connections between the fuel tank and the motor.

Also I plan to replace the fuel line primer bulb. What is the best one made?

And Sta-Bil is typically the stabilizer I use.

[Jason2tpa]

IMO, my recommendation:
I would drain your carb bowls and filter bowl first, shock using a portable tank with a gallon or two gas and the 2oz. per gallon Ring free concentration, pump primer bulb until hard and fuel filter and carb bowls full, run about 10 minutes, let set an hour or two, and re-fire your engine. Hopefully your "low RPM's (1,000 - 2,000) intermittent engine stumble or misfire" will disappear

Chuck- what's the purpose behind using a separate fuel tank for the shock treatment?

For my fuel system that would require opening my fuel line behind a step down connector a few feet from where fuel line enters cowling. It can be done, sure. But let's say instead I started the shock treatment with an empty tank (below deck tank), dumped in the appropriate amount of RF and followed it with 2 gals of fuel. Then follow same procedure as you detailed. Any difference?

[TownsendsFJR1300]

Chuck- what's the purpose behind using a separate fuel tank for the shock treatment?

For my fuel system that would require opening my fuel line behind a step down connector a few feet from where fuel line enters cowling. It can be done, sure. But let's say instead I started the shock treatment with an empty tank (below deck tank), dumped in the appropriate amount of RF and followed it with 2 gals of fuel. Then follow same procedure as you detailed. Any difference?

Jason, RF shock dose is 2 oz / ONE GALLON.

It's generally easier to use a separate tank with fresh fuel (and no crap floating on the bottom to get sucked into the system). Generally 6 gallons is enough for the shock treatment.

__________________________________________________ __________________________________

For the OP, sounds like you found the issue.

IMO, I would run a new fuel line (get rid of all the connectors) MARINE GRADE (so Ethanol doesn't eat it).

Under the cowl, Yamaha uses zip ties BUT their NOT what you buy at the store. They have a rounded edge on the INSIDE (where it tightens down) for more contact area: http://www.boats.net/parts/detail/ya...%20Numbers%207

The "best" primer bulb I've found is the genuine Yamaha bulb (about $20.00), noticeably different than the cheapo's.

As for clamps, Otiker clamps are generally used however I use "Ideal" mini screw clamps which have served me fine W/O issue and are easily removed if need be.

Evinrude (and now others) have available this style clamp which works really, really well (see below) :
https://www.amazon.com/Heavy-Double-...ic+Hose+Clamps

Obviously get the correct size...

I haven't had good luck with Stabil and avoid it.

If you don't have a fuel / water separator I'd install one. Cheap insurance and helps keep crap out of the engine. With the see thru bottom(and drain), any water found is simply removed by turning the valve..





Double click to enlarge

[cpostis]

Update: I have not yet had a chance to buy some Ring Free and run it on a portable tank, but I've used the motor a few times since my last post and, if the problem hasn't disappeared entirely, the motor is running better than before.

Here is what happened: I noticed that one of the fuel line connections between the internal fuel tank and the motor did not have any sort of clamp on it. I put on a small stainless steel hose clamp and tightened that up, and the "lean sneeze" or whatever problem it was more or less went away. I'm theorizing that maybe some air was leaking into the fuel line from this unclamped connection.

I need to figure out the best way to clamp these fuel lines. I don't think typical plumbing hose clamps are the best, and the other fuel line connections on this boat are clamped with zip ties (cheesy installation by dealer when repowering). There are at least 7 separate fuel line connections between the fuel tank and the motor.

Also I plan to replace the fuel line primer bulb. What is the best one made?

And Sta-Bil is typically the stabilizer I use.

I prefer the genuine Yamaha primer bulb with full surface stainless steel crimp clamps. Of course, make sure your hose barb connections on the bulb match your hose ID.

YAMAHA 5/16” or 8MM OEM PRIMER BULB PUMP ASSEMBLY (WITHOUT HOSE)

[IMG]YamahaPrimerBulb by Charles Postis, on Flickr[/IMG]

Clamps, most will say that "worm gear" screw clamps are sufficient on low pressure and/or vacuum connections.

I have another opinion. While checking/replacing my HP fuel lines I checked my low pressure/vacuum fuel lines as well. Here are some images with descriptions.

Hose damaged by "worm screw clamp" (cuts and abrasion)
[IMG]Fuel Hose Abrasion.Worm Screw Clamp1 by Charles Postis, on Flickr[/IMG]

Hose undamaged by "crimp clamp" (no cuts or abrasion)
[IMG]Fuel Hose Good.Crimp Clamp by Charles Postis, on Flickr[/IMG]

If you use the crimp clamps you will need the appropriate crimper and appropriate size clamps. The clamps must fit the OD of the hose with little clearance before crimping. If they are to tight, you will not be able to crimp completely (beyond the first "catch" on the clamp) . If they are too loose, you will not be able to tighten for a good grip.

I purchased the clamps and crimper at Home Depot.
[IMG]PEX Clamp by Charles Postis, on Flickr[/IMG]

[cpostis]

Chuck- what's the purpose behind using a separate fuel tank for the shock treatment?

For my fuel system that would require opening my fuel line behind a step down connector a few feet from where fuel line enters cowling. It can be done, sure. But let's say instead I started the shock treatment with an empty tank (below deck tank), dumped in the appropriate amount of RF and followed it with 2 gals of fuel. Then follow same procedure as you detailed. Any difference?

For the attempt on cleaning carbs, I would only want to use a small amount of gasoline treated with "shock treatment" ratio.

Sure, you could do what you say, but seems like more work to me. (Drain tank and fill with amount of Ring Free treated of proper ratio).

I just mix the ratio I want in the portable tank, remove the fuel inlet to the fuel bowl filter connection, and attach my portable tank through the primer bulb on the portable tank directly to the fuel bowl inlet on the engine.

[IMG]PortableTank by Charles Postis, on Flickr[/IMG]

[pstephens46]

90465-11M10-00 YAMAHA CLAMP (ZIP TIES)

So Yamaha sell their zip ties by the each? $1.65? Really?

How about a bag of 50? For $50.00. No wonder people are using plumbing supplies.....

[cpostis]

90465-11M10-00 YAMAHA CLAMP (ZIP TIES)

So Yamaha sell their zip ties by the each? $1.65? Really?

How about a bag of 50? For $50.00. No wonder people are using plumbing supplies.....

Yup, the "stainless steel crimp clamp" I refer to and "clips" how Yamaha refers it to, are $10.83 each from Boats.net , comparable to less than 55 cents each at HD.

Sometimes I will substitute "Genuine Yamaha" with alternatives, if they appear to be equal or better than the Yamaha Genuine Part.

[pstephens46]

I like the Evinrude style Scott posted above. Might be a little trouble in tight spaces.