Rebuild carbs or not?

[rpelton]

I have a 2004 40 hp 4 yamaho 4 stroke. Carbs were recently rebuilt. Boat sat for 3 months and now boggs down under load in mid-range throttle. Once on a plain it runs great.
I have checked fuil flow, compression and spark and all seems good.
If I take the carb apart to clean it out, do I need a new carb kit?
Should I try running some Ring Free or another product through it first? I've alreading drained the carbs and started with fresh fuel, so I'm sure that is not an issue either.
Thanks for your help.
Bob

 

[randy_252]

Re: Rebuild carbs or not?

Rodbolt explained to you what you need to do. He may be a bit forceful, but he knows.....

One must have a system of troubling shooting to ensure where/what the problem is.

1. check tank....any trash? dump and clean if possible.
2. inspect fuel hoses/fittings.....looks bad....replace it.
3. make sure the fuel bulb arrow is pointing UP. not side ways.


When you have completed the above process move down.

1a.Dont fool with any linkages. and before starting turn the fuel adjustment needle valve in until it bottems out. Now write it down there is 1 per carb. example...#1-1 1/4

1. if you want to pull the carbs it's not to hard. IF they were just rebuilt no since repalcing parts. Just be careful when tearing them down. Pay attention to the fuel ports...go buy you a torch tip cleaner and match it to the port you want to poke it thru. Do not make the port bigger.

2. pay attention to the float and valve...it has to move freely.

3. now soak them in some type of carb soak. (depends on how the inside looks vs. your chance of having to do it again.

4. now reinstall everything....it's not to bad just a PIA. I use to do mine alot until I started using stablizer and draining ALL fuel from my motor.

5. At this point you can do 2 things.

1. go run ur boat. either it will or wont. if it wont do #2

2. go back to rodbolt's thread and do what he told ya. he was trying to see if the fuel pump was working.

 

[JUSTINTIME]

Re: Rebuild carbs or not?

never soak carbs in auto carb clearner also

 

[rpelton]

Re: Rebuild carbs or not?

Thanks so much for you and Rodbolt's help. I am trying to get the hang of using the forum so I apologize for my niave behavior.


1. check tank....any trash? dump and clean if possible.

- I put a clean tank on, fresh fuel and refilled the fuel separator and flushed the lines with fresh fuel. Also drained the carbs.

2. inspect fuel hoses/fittings.....looks bad....replace it.

- Carefully inspected all of this.

3. make sure the fuel bulb arrow is pointing UP. not side ways.

- I can't find a fuel bulb arrow. Is this the squeeze bulb on the fuel line that goes from the fuel tank to the engine, or is this something on the engine/carbs themselves?


When you have completed the above process move down.

1a.Dont fool with any linkages. and before starting turn the fuel adjustment needle valve in until it bottems out. Now write it down there is 1 per carb. example...#1-1 1/4
- They are all set exactly the same. 1 and 1/4 turn from all the way in. Noted! Could this be the problem, never having been adjusted properly?

I am awaiting the arrival of the service manual from Yamaha, so I am hesitant to further rip down the carbs without.

In the meantime, I removed the drain screws, drained the carbs (nothing yukky came out) and removed the three adjustment jet screws (I carefully noted where the get adjusted to).

I shot a bunch of carb cleaner through and blew it out several times with air hose. I repeated this several times, letting it sit for 30 minutes one of the times.

I then added Ring Free to the gas in a "shock" dose(6 ounces in 3 gal of gas), as described by Yamaha to clean your carburator. This has not changed the problem yet, so I will run the boat in the water later today at high RPMs, to run the gas cleaner treatment through.
- Is this o.k. to do?

After the manual arrives, I will follow the rest of your suggestions and completely clean out the carbs.

If that doesn't work, I will go back to rodbolt's thread and do what he said. I will have to get a vacum guage to do this, that is why I have not yet done this.

Thank again and again.

Bob

 

[Ray Neudecker]

Re: Rebuild carbs or not?

Good luck. That is a perfect recipe for disaster. You really don't want to try running it hard until you are sure the problem is solved or you may blow that powerhead. Rod bolt was trying to help you solve the problem and save your motor. Not sure why you don't want to follow his advice. These types of repairs are critical to the life of your motor.

 

[JUSTINTIME]

Re: Rebuild carbs or not?

Good luck. That is a perfect recipe for disaster. You really don't want to try running it hard until you are sure the problem is solved or you may blow that powerhead. Rod bolt was trying to help you solve the problem and save your motor. Not sure why you don't want to follow his advice. These types of repairs are critical to the life of your motor.

X2

 

[fpelton]

Re: Rebuild carbs or not?

Ray and Justintime,

Ease off on me. Clearly I don't have the wisdom that some others have when it comes to these motors. I am following Randy and Rodbolt's help, so try not to suggest the contrary. I indicated that I followed Randy's advice step by step. I also asked them their opinion on using the ring free and running the boat at high speed.

I am waiting for the manual to arrive so that I can properly clean the carb according to Randy's rec and am trying to locate a vacum gauge to perform Rodbolt's test (I mentioned this in the last post- so please refraim from an attack).

In the meantime, like others, it is hard to sit and wait so I am just doing what I thought was a little cleaning and minor maintanence. Yamaha recomends the Ring Free as a general cleaner and maintanence procedure, so I don't think it will "blow the powerhead" . I was simply asking the experts, that would be Randy or Rodbolt's, opinion.

I find this forum to be of exceptional quality and help and thank Rodbolt and Randy for helping newbies like me work on their engines.

Best,
Bob

 

[randy_252]

Re: Rebuild carbs or not?

never soak carbs in auto carb clearner also

Please explaiin why not. seeking to understand?

thanks

 

[JUSTINTIME]

Re: Rebuild carbs or not?

never soak carbs in auto carb clearner also

Please explaiin why not. seeking to understand?

thanks

according to marine manufactures, they say what the carbs are sealed with (Ur fuel and air passages ports) and the sealant used on the carb itself, auto carb cleaner is too harsh on the sealant causing it to break down and not seal properly

if a marine mechanic says it is OK, find another one

call the manufactures, the Will tell u

 

[randy_252]

Re: Rebuild carbs or not?

The buld=the nigger tittie. on the fuel hose!!
Does it pump up tight ?
Do you just keep pumping on it.
It must pump up tight.
If it don't look for the carb or carbs that is spilling gas out the top. It needs attention if you do 1 do them all.

If you tear down the carbs you will need something small to make sure the jets are clear.

If...If this was my boat motor I would all of what I said to you down the nigger tittie.

Put it in the water, and see if it will run.

If it didn't run right, spend the money and take to a shop.

Don't listen to me....I'm just a Lawyer....

 

[Ray Neudecker]

Re: Rebuild carbs or not?

The ring free should not harm the motor and really don't know of anything negative in using it, The danger is from running the motor wide open with a fuel restriction.

 

[rpelton]

Syncing the carbs -Yamaha 40 4 stroke

Syncing the carbs -Yamaha 40 4 stroke

I rebuilt carbs and cleaned with cleaner and pressured air. Still no change. I tried adjusting one of the screws that sync them and performance improved. If this is the problem, I'd like to get them perfect.
1. Could out of sync carbs cause the bogging?
2. Are these synced by ear or can I purchase some sort of gauge?
Thanks,
Bob

 

[Ray Neudecker]

Re: Rebuild carbs or not?

Out of sync carbs or misadjustment of the idle air screws can cause the problem. I have always gone to the factory adjustments and fine tuned by ear.

 

[jjdluz]

Re: Rebuild carbs or not?

randy,why fuel bulb arrow point up,any reason?thanks.