[gator79]

I have a pair of 1989 130 hp yamahas. one will idle fine but bogs and sputters under load. It has been sitting for 5 months and probably needs the carbs cleaned. are there any special tricks to look for on theese carbs? I am a certified auto tech and have rebuilt auto carbs before, but it has been a long time, they quit using them about 20 years ago. If anyone has any tips or advice or thinks this may not be the problem please let me know.thanks,Mark

[seahorse5]

Just like with auto carbs, use care to take them apart and clean out every passageway. First obtain the correct service manual and study closely the adjustment and synchronization section, as those are important for drivability.Don't have a heart attack when you see the Yamaha carb kit prices and take your model number whith you to be sure to get the right ones.There is an old service bulletin about drilling out the blind passageway from the fuel inlet fitting to the float valves. Ask your dealer to copy it for you. It is also reprinted almost every year in the annual Marine Technical Guide. In some cases, rust from the steel screws in the fuel pump, build up and cause intermittent restrictions. If the fuel pump is original, replace it.

[rodbolt]

hello yep what seahorse says. be hesitant about drilling the cleanout passage. do it only if nessasary. 99%of the problems are in the idle pick-ups in the fuel bowl. that is where the solids settle as the feul evaporates. I dont recommend soaking the carb throttle body assy in a dip solution. I use CRC 06064 cleaner. the bowls can be soaked for a bit if nessasary but usually I can clean 2 carbs with one can. buy new pumps and the job is complete. good luck and keep posting

[seahorse5]

That rusty over-torqued old RODBOLT is correct. Don't worry about drilling out the passage unless the carbs are very dirty, or if you end up with an intermittent power loss while running. Not every carb needs it, I should have made that more clear.The idle jets in the bottom of the float bowls are very small, and most of the time, frozen in place. Use a spray carb cleaner, or better yet, something like Bombardier Engine Tuner, or another "decarbonizer" to soak inside the float bowl overnite. It is not powerful enough to strip the sealing compound off the aluminum, but will clean out gummed fuel deposits beautifully.

[gator79]

Rodbolt, are you talking about replacing the fuel pump also?i just bought the boat and the previous owner said the fuel line at the motor was sucking air and he replaced the line and fitting. has anyone heard of that? I am not real sure of the repair history of theese motors so i will go ahead and replace the fuel and water pumps. I have the yamaha factory service manual but it does not mention carb syncronizing. what are your thoughts on removing oil injection. if anyone has any car or truck questions I will be happy to answer them. thanks for everyones input.

[seahorse5]

Fuel pumps are Yamaha's weak point. Replace it as it is a reasonable $39.

[wtrojan]

Quick connect fuel line fitting sucking air? Well gator, been thereÂ… Engine similar to yours 130s, yamaha V4 from early 90Â’s. Female partÂ’s gasket got dented and allowed the air getting in with higher revs. Also, couldnÂ’t agree more with the fuel pump opinions above. In mine, the valves were the weak point, so if you can change the pump without hesitation.

[gator79]

should I replace the diaphram or the entire fuel pump?

[wtrojan]

Changing the diaphragm wonÂ’t hurt, but if the pump inner checkvalves are bad, this will not solve the problem. IÂ’m not sure if you can get the valves and a diaphragm in a kit, if not, the whole pump assembly replacement would be recommended.