Larger Idle Jet? 2005 50 TLRD

[margaritaville]

I have had a continual problem with the carbs clogging. I have had the engine back to the dealer many times and have done all the recommended things.

Change fuel tank
10 micron filter
replace fuel lines.

Nothing seems to help. Every time it is the same thing. Idle is perfect and full throttle is perfect. It is the slow acceleration that causes the engine to bog down and die. When I pull the carbs and clean the low speed jet the problem is fixed.


Long one short, Yamaha mentioned putting larger jets in for the low idle the 50 HP uses a 62 and the 60hp uses a 65.

Can this done without many mods?

[robert graham]

Seems like a hair-brained idea to me. If your fuel is fresh and clean then the jets are not going to plug up, and enlarging them by a few thousandths of an inch to prevent plugging just makes no sense at all. Can you drain carbs from time to time to be sure there's no water/debris/crud in them? It's a good idea.

[99yam40]

How do you shut down the motor at the end of a trip for storage?
How long between trips normally?
Do you run it out of fuel, leave the carbs full, leave the hose hooked up or disconnected?
Where do you store the fuel tank?
Where is the boat kept and what kind of climate is it stored in?

[margaritaville]

How do you shut down the motor at the end of a trip for storage?
How long between trips normally?
Do you run it out of fuel, leave the carbs full, leave the hose hooked up or disconnected?
Where do you store the fuel tank?
Where is the boat kept and what kind of climate is it stored in?

The boat is used 4-5 times per week in the summer and at least once per week in the winter.
The fuel never has a chance to get old.
We never ran it out of fuel at the end of the day, but are going to start now.
The tank is a 6 gallon yamaha tank. we leave it on the boat but the boat is stored under a shade tree.

The tank is covered so that no rain water can get in the tank.

The jets inside feel abrasive so the next time around, I am going to replace them instead of ultrasonic cleaning them.

[margaritaville]

Seems like a hair-brained idea to me. If your fuel is fresh and clean then the jets are not going to plug up, and enlarging them by a few thousandths of an inch to prevent plugging just makes no sense at all. Can you drain carbs from time to time to be sure there's no water/debris/crud in them? It's a good idea.

When the carbs are pulled, the main jet is clear but the pilot jet has a gummy build up, like when fuel evaporates.

[robert graham]

Just drain each carb onto a clean white rag so you can see what comes out. with drain screws out, pump primer a few times to "flush" float chamber with fresh gas, replace plugs(10MM brass plugs on bottom/side of each carb). Use the Stabil Marine (Walmart $20/quart)in your gas all the time. Good luck and let us know how it works.

[margaritaville]

Just drain each carb onto a clean white rag so you can see what comes out. with drain screws out, pump primer a few times to "flush" float chamber with fresh gas, replace plugs(10MM brass plugs on bottom/side of each carb). Use the Stabil Marine (Walmart $20/quart)in your gas all the time. Good luck and let us know how it works.

I use the marine stabil all the time.

I have done the white rag/carb trick. The gas is clean.


what would replacing the drain plug do?

I am open to any new suggestion. I own 3 boats and 1 jet ski and this is the only engine that gives me trouble.

[99yam40]

The boat is used 4-5 times per week in the summer and at least once per week in the winter.
The fuel never has a chance to get old.
We never ran it out of fuel at the end of the day, but are going to start now.
The tank is a 6 gallon yamaha tank. we leave it on the boat but the boat is stored under a shade tree.

The tank is covered so that no rain water can get in the tank.

The jets inside feel abrasive so the next time around, I am going to replace them instead of ultrasonic cleaning them.

Draining the bowls would be better than running it out, that leaves some fuel in bowls to evaporate and plug things/ This is puzzeling so let us know if you find your problem

[robert graham]

"Replacing drain plugs" means to put them back in after draining carb float chambers. Maybe pour some of your fuel into a clear glass container, let it sit for a while and see if there is any cloudiness or particulate matter in it. What is you gas tank made of and is it new/really clean on the inside? Did you replace your fuel hoses with real "marine" grade fuel hose. It sounds like your fuel delivery system is somehow contaminating your fuel and then gumming up your carb jets. Keep us posted with results.

[margaritaville]

Draining the bowls would be better than running it out, that leaves some fuel in bowls to evaporate and plug things/ This is puzzeling so let us know if you find your problem

Draining the bowls (all 3) 4-5 times per week is not an option. It has been puzzling to everyone.

[margaritaville]

"Replacing drain plugs" means to put them back in after draining carb float chambers. Maybe pour some of your fuel into a clear glass container, let it sit for a while and see if there is any cloudiness or particulate matter in it. What is you gas tank made of and is it new/really clean on the inside? Did you replace your fuel hoses with real "marine" grade fuel hose. It sounds like your fuel delivery system is somehow contaminating your fuel and then gumming up your carb jets. Keep us posted with results.

The fuel is perfect. It is crystal clear. I have gone through 8 yamaha poly tanks in 5 years so I would say they are new. LOL
All fuel lines are where replaced with OMC ethanol rated fuel lines. 3/8 to the engine and 1/4 inside.

The original lines from yamaha had a problem with the ethanol and i thought I had the problem resolved but it has come back.

[99yam40]

The fuel is perfect. It is crystal clear. I have gone through 8 yamaha poly tanks in 5 years so I would say they are new. LOL
All fuel lines are where replaced with OMC ethanol rated fuel lines. 3/8 to the engine and 1/4 inside.

The original lines from yamaha had a problem with the ethanol and i thought I had the problem resolved but it has come back.

What happened to all the tanks?
What kind of a problem did the Yamaha fuel lines have?
How long did it do well after replacing the lines before the problem showed back up?

[margaritaville]

What happened to all the tanks?
What kind of a problem did the Yamaha fuel lines have?
How long did it do well after replacing the lines before the problem showed back up?

The original fuel lines were rotting away on the inside (Ethanol Gas)
I got 18 months out of the last carb cleaning.

All the other tanks were thrown out at the recommendation of Yamaha. 40 bucks for a tank or 75 to have it cleaned.
I don't think the tanks were the problem. If it was, the 10 micron filter would catch it.

Something is happening to the gas AFTER the 10 micron filter but noone can tell me for sure.

[99yam40]

I have read that some of the lines that have a vinyl inner liner do not last but a year or so with ethanol. Best way to look at it is to cut a small section off and split it open to look at it