03 yamaha nobody can seem to fix

jm8422 · Feb 18, 2010

I have a 2003 yamaha carb. The motor runs rough and smokes at idle all the way up to 2000 rpms seems like its loading up. over 2000 it runs alot better but still a little rough. I put brand new carbs on. New fuel pumps, plugs, changed the water sep. no water. Filter on motor is clean. Every time I start it I have to hit the warmup lever to clear it out smokes alot clears up a little but still runs like crap untill we get over 2000 any ideas I tryed everything. Thanks John

JustJason · Feb 18, 2010

Re: 03 yamaha nobody can seem to fix

Start with the basics, compression test and spark check on all cylinders.
If it checks out, move on to a sync and link, doubel check base and advance timing. If, this engine has one, make sure the oil pump metering rod is in the correct position. If they get disconnected they go wide open and can over-oil the engine.

Do you have a manual for your engine?

Welcome to iboats

jm8422 · Feb 18, 2010

Re: 03 yamaha nobody can seem to fix

Comp is good all around 110. spark good also. Will check oil pump rod. Dont have a manuel. Thanks JJ

rodbolt · Feb 18, 2010

Re: 03 yamaha nobody can seem to fix

wonder how many carbed models yamaha offered in 2003.
we need a model number.

jm8422 · Feb 18, 2010

Re: 03 yamaha nobody can seem to fix

I think the model number is 150xtrb Thanks

robert graham · Feb 19, 2010

Re: 03 yamaha nobody can seem to fix

Just curious, but why did you put new carbs on it? Are carb floats set correctly? Good Luck!

jm8422 · Feb 19, 2010

Re: 03 yamaha nobody can seem to fix

The carbs were replaced last year because the motor sat for 3 months and they ended up being corroded pretty bad. Rebuild wasnt good enough and didnt want anymore down time. I just Replaced.

99yam40 · Feb 19, 2010

Re: 03 yamaha nobody can seem to fix

To me, corroded carbs mean there was water in the fuel system to cause the corrosion. They will not corrode with just fuel, your tank may need to be cleaned along with your new carbs.
Buy a manual for your motor and make sure the sync and link has been done exactly as it says. And the carbs are adjusted properly.

jm8422 · Feb 19, 2010

Re: 03 yamaha nobody can seem to fix

They said the cause was the ethanol in the fuel. I never set any linkage on carbs just bolted new ones on and hooked everything back up the way it was. only adjusted low speed. What are the chances the link and sinc is right. Thanks John

99yam40 · Feb 19, 2010

Re: 03 yamaha nobody can seem to fix

Who is they?

Ethanol will grab water and settle out on the bottom, that will cause the problems in the carbs and the tank. This will ruin the octane rating of the fuel. Did you drain the tank, clean, and put in fresh fuel?

Link and sync needs to be done any time the carbs are pulled. The position of the carbs can be just a little off from before and change things

robert graham · Feb 19, 2010

Re: 03 yamaha nobody can seem to fix

If you just bolted those new carbs on without any adjustments then they have to be out of whack...that's probably your problem..You can get a Yamaha book and it tells how to linq and sync carbs, and it's critical for motor to run correctly! Good Luck!

jm8422 · Feb 20, 2010

Re: 03 yamaha nobody can seem to fix

I ordered the manuel to do the link and sinc. The reason I dont think that is the problem is its doing the same thing it was doing before the new carbs. One thing I forgot to mention is there is no change in rpm when I pull the bottom plug wires off. comp is good and its getting spark just seems like to much fuel. Thanks for the input guys.

seahorse5 · Feb 20, 2010

Re: 03 yamaha nobody can seem to fix

jm8422 said:
One thing I forgot to mention is there is no change in rpm when I pull the bottom plug wires off. comp is good and its getting spark just seems like to much fuel.

Have you checked for pinholes or tears in the fuel pump diaphragms?

99yam40 · Feb 20, 2010

Re: 03 yamaha nobody can seem to fix

are you are absolutely sure it has good compression and good spark on all cylinders?
if it is still doing the same thing as before the replacing of the carbs, fuel pumps, and plugs you probable need to make sure the electronics are doing what they are suppose to. Use the manual to troubleshoot them to make sure it is firing properly and not having weak or intermittent spark.

If you do have good compression and good spark on all cylinders and the timing is were it is suppose to be at, at the different times then you are back to the air/ fuel ratio not correct. Too lean or too rich will not allow it to burn properly.
Plugged passages/jets, miss adjusted carbs, or air(vacuum) leaks will cause certain cylinders to be too lean to fire properly.
Too rich may come from trash in needle and seat, miss adjusted floats or carbs, pin hole in pump diaphragm,or wrong size jets.
Some of the motors have different size jets in the carbs on different cylinders.

jm8422 · Feb 25, 2010

Re: 03 yamaha nobody can seem to fix

Well did the link and sinc no change. Checked the comp. again 110 across the board. spark is good. Still seems like a fuel problem. When I pull the bottom plug wires off theres no change and if I choke out the bottom carb no change. Seems like bottom cyls are loading up. new carb no change new pumps no change. Is there anyplace else fuel could be dumping into the bottom cly. from. Thanks John

99yam40 · Feb 25, 2010

Re: 03 yamaha nobody can seem to fix

how are you testing spark?

Have you taken any CDI output voltage reading or coil resistance reading to make sure there is not any problems or differences from the specs or each component?

I do not know what could dump extra fuel into the bottom 2 cylinders on that motor. I take it you are talking about 5&6.
Have you checked which cylinders provide the pulses for the fuel pumps?

heliockjent · Feb 26, 2010

Re: 03 yamaha nobody can seem to fix

Hello jm8422
I have one solution for you.
There should be a number stamped on your original jets,It does sound as if the motor may be running lean at idle so if you dont find any kind of restriction in the jet orafice you may want to try the larger jet.Hopefull it works for you.

turn2 · Feb 26, 2010

Re: 03 yamaha nobody can seem to fix

Since we are guessing. try putting your hand over the carbs while the motor is running, 1 at a time and see if it sucks your hand up tight. If the bottom does not pull air in, check the reed valves. If just one flap is bent or gone it will affect the fuel draw, and appear to be flooding.When running on a hose does a black film form on the water running around on the ground..

bigbrookie · Feb 26, 2010

Re: 03 yamaha nobody can seem to fix

i am by no means an expert, but thought i'd share the problem i had with my 2001 60 last year. it was running real ruff and would fall on it's face at full speed and then i'd have to limp into the marina. we checked everything in the motor, comp, carbs, spark, jets, ect... it turned out to be rust in the gas tank. put an inline filter in, and havn't had a problem since. just a thought.

jm8422 · Feb 26, 2010

Re: 03 yamaha nobody can seem to fix

Tryed running on different tank no change.Bottom cyl are def. running rich. engine smokes like crazy at low speed and idle. I just checked the spark not the voltage could the voltage be different at low speed.Thanks John

03 yamaha nobody can seem to fix

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