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Ask Dominick Your Own Question
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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Have a Yamaha 50 tlr, won't get above 1300 rpm when engaged

Customer Question

Have a Yamaha 50 tlr, won't get above 1300 rpm when engaged with a load/ in the water
Submitted: 1 year ago.
Category: Boat
Expert:  Jeff G. replied 1 year ago.

What does it do? Stumble? Just quit? Just won't go faster or more rpm?

Customer: replied 1 year ago.
Just shuts off, maybe starves for fuel. The more I run it regularly, the better it performs. I' rebuilt the carbs, they're sweet. Replaced the main fuel line up to the exterior of engine with new prime bubble, empty and replaced fuel. Added sea foam to fuel. Revs fine in neutral, under load can only get to around 1300 rpm, pushing higher stalls the engine
Customer: replied 1 year ago.
Replaced fuel pump too
Expert:  Jeff G. replied 1 year ago.

There are a couple possibilities. If you have or can get a timing light, put it on the top cylinder and as you slowly raise the throttle speed see if the timing moves.

When you rebuilt the carbs did you use new gasket/seals? Did you remove and clean the jets or just use carb cleaner?

Don't rev in neutral above 2000 rpm.

Get a small oil can and with the air silencer off the front of the carbs spray a little fuel into the throat of the carbs one at a time. Just a little. Does the rpm go up? What does it do? Post back the results.

Customer: replied 1 year ago.
Was a mechanic back in the day, tore the carbs down to the bone anWas a mechanic back in the day, tore carbs down to the bone and back together, they're good. I'll do the fuel request tomorrow and get back. New plugs a btw. Just acts like it starves for fuel.....
Expert:  Jeff G. replied 1 year ago.

Try squeezing the primer bulb as you accelerate. Where did you get the primer bulb, hopefully not Walmart.

Customer: replied 1 year ago.
Don't remember where I got the bubble, either WalMart or academy. Tried squeezing while running. Took carbs completely apart, jets,etc. I did read a stream that mentioned an adjustment that resolves the issue but I can't find it again and breezed over it too fast to remember. I have also emptied the gas tank and refilled with fresh gas and seafoam.
Customer: replied 1 year ago.
The middle carb has some type of electronic needle value thing, could that be the issue, I didn't take it apart for cleaning
Customer: replied 1 year ago.
I'll do the spray bottle on Saturday, won't have time before that.
I'm planning a trip to lake fork in the middle of next week, would like it working by then but am taking it anyway. Any thing I do has to be on Saturday or Sunday afternoon
Expert:  Jeff G. replied 1 year ago.

The needle valve thing is a starter, primer, it is open when cold allowing more fuel. As the motor runs it heats up and shuts off the additional fuel. Kind of a an automatic primer system. To test it just remove it, turn the key to on and watch the needle, if it moves it is probably fine.

Did you try adjusting the idle mixture?

When you accelerate does it just stumble and want to die? If so turn the idle mixture out 1/8 turn at a time, allowing 10 seconds between adjustments.

Customer: replied 1 year ago.
Where is the idle adjustment located?
Expert:  Jeff G. replied 1 year ago.

Top back of the carbs, may be under a small brass plug. #26 in the drawing. If the plug is in place carefully drill the plug and pop it out with an awl.